Update links

Update changelog for version 7.3.3
Merge pull request #1006 from marc-mabe/fix-958-error_description
2025-05-31 14:12:07 +05:30 · 2019-03-29 18:19:35 +00:00 · 2019-03-29 18:18:35 +00:00 · 2019-03-29 16:28:33 +00:00 · 2019-03-29 16:00:26 +01:00 · 2019-01-22 20:59:33 +00:00
85 changed files with 3041 additions and 1292 deletions
--- a/.gitattributes
+++ b/.gitattributes
@@ -10,4 +10,5 @@
 /phpunit.xml.dist export-ignore
 /CHANGELOG.md export-ignore
 /CONTRIBUTING.md export-ignore
-/README.md export-ignore
+/README.md export-ignore
+
--- a/.styleci.yml
+++ b/.styleci.yml
@@ -4,6 +4,7 @@ enabled:
  - binary_operator_spaces
  - blank_line_before_return
  - concat_with_spaces
+  - fully_qualified_strict_types
  - function_typehint_space
  - hash_to_slash_comment
  - include
@@ -29,7 +30,6 @@ enabled:
  - phpdoc_inline_tag
  - phpdoc_no_access
  - phpdoc_no_simplified_null_return
-  - phpdoc_order
  - phpdoc_property
  - phpdoc_scalar
  - phpdoc_separation
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,24 +1,33 @@
 language: php

+dist: trusty
 sudo: false

 cache:
  directories:
-  - vendor
+    - vendor
+
+env:
+  - DEPENDENCIES=""
+  - DEPENDENCIES="--prefer-lowest --prefer-stable"

 php:
-  - 5.5.9
-  - 5.5
-  - 5.6
  - 7.0
-  - hhvm
+  - 7.1
+  - 7.2
+  - 7.3

 install:
-  - travis_retry composer install --no-interaction --prefer-source
+  - composer update --no-interaction --prefer-dist $DEPENDENCIES

 script:
-  - vendor/bin/phpunit
+  - vendor/bin/phpunit --coverage-clover=coverage.clover
+  - vendor/bin/phpstan analyse -l 7 -c phpstan.neon src tests
+
+after_script:
+    - wget https://scrutinizer-ci.com/ocular.phar
+    - php ocular.phar code-coverage:upload --format=php-clover coverage.clover

 branches:
  only:
-    - master
+    - master
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,308 +1,500 @@
 # Changelog
+All notable changes to this project will be documented in this file.

-## 5.1.0 (released 2016-06-28)
+The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
+and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).

-* Implemented RFC7636 (Issue #574)
-* Unify middleware exception responses (Issue #578)
-* Updated examples (Issue #589)
-* Ensure state is in access denied redirect (Issue #597)
-* Remove redundant `isExpired()` method from entity interfaces and traits (Issue #600)
-* Added a check for unique access token constraint violation (Issue #601)
-* Look at Authorization header directly for HTTP Basic auth checks (Issue #604)
-* Added catch Runtime exception when parsing JWT string (Issue #605)
-* Allow `paragonie/random_compat` 2.x (Issue #606)
-* Added `indigophp/hash-compat` to Composer suggestions and `require-dev` for PHP 5.5 support
+## [Unreleased]

-## 5.0.3 (released 2016-05-04)
+## [7.3.3] - released 2019-03-29
+### Added
+- Added `error_description` to the error payload to improve standards compliance. The contents of this are copied from the existing `message` value. (PR #1006)

-* Fix hints in PasswordGrant (Issue #560)
-* Add meaning of `Resource owner` to terminology.md (Issue #561)
-* Use constant for event name instead of explicit string (Issue #563)
-* Remove unused request property (Issue #564)
-* Correct wrong phpdoc (Issue #569)
-* Fixed typo in exception string (Issue #570)
+### Deprecated
+- Error payload will not issue `message` value in the next major release (PR #1006)

-## 5.0.2 (released 2016-04-18)
+## [7.3.2] - released 2018-11-21

-* `state` parameter is now correctly returned after implicit grant authorization
-* Small code and docblock improvements
+### Fixed
+- Revert setting keys on response type to be inside `getResponseType()` function instead of AuthorizationServer constructor (PR #969)

-## 5.0.1 (released 2016-04-18)
+## [7.3.1] - released 2018-11-15

-* Fixes an issue (#550) whereby it was unclear whether or not to validate a client's secret during a request.
+### Fixed
+- Fix issue with previous release where interface had changed for the AuthorizationServer. Reverted to the previous interface while maintaining functionality changes (PR #970)

-## 5.0.0 (released 2016-04-17)
+## [7.3.0] - released 2018-11-13
+
+### Changed
+- Moved  the `finalizeScopes()` call from `validateAuthorizationRequest` method to the `completeAuthorizationRequest` method so it is called just before the access token is issued (PR #923)
+
+### Added
+- Added a ScopeTrait to provide an implementation for jsonSerialize (PR #952)
+- Ability to nest exceptions (PR #965)
+
+### Fixed
+- Fix issue where AuthorizationServer is not stateless as ResponseType could store state of a previous request (PR #960)
+
+## [7.2.0] - released 2018-06-23
+
+### Changed
+- Added new`validateRedirectUri` method AbstractGrant to remove three instances of code duplication (PR #912)
+- Allow 640 as a crypt key file permission (PR #917)
+
+### Added
+- Function `hasRedirect()` added to `OAuthServerException` (PR #703)
+
+### Fixed
+- Catch and handle `BadMethodCallException` from the `verify()` method of the JWT token in the `validateAuthorization` method (PR #904)
+
+## [4.1.7] - released 2018-06-23
+
+### Fixed
+- Ensure `empty()` function call only contains variable to be compatible with PHP 5.4 (PR #918)
+
+## [7.1.1] - released 2018-05-21
+
+### Fixed
+- No longer set a WWW-Authenticate header for invalid clients if the client did not send an Authorization header in the original request (PR #902)
+
+## [7.1.0] - released 2018-04-22
+
+### Changed
+- Changed hint for unsupportedGrantType exception so it no longer references the grant type parameter which isn't always expected (PR #893)
+- Upgrade PHPStan checks to level 7 (PR #856)
+
+### Added
+- Added event emitters for issued access and refresh tokens (PR #860)
+- Can now use Defuse\Crypto\Key for encryption/decryption of keys which is faster than the Cryto class (PR #812)
+
+### Removed
+- Remove paragone/random_compat from dependencies
+
+## [7.0.0] - released 2018-02-18
+
+### Added
+- Use PHPStan for static analysis of code (PR #848)
+- Enforce stricter static analysis checks and upgrade library dependencies (PR #852)
+- Provide PHPStan coverage for tests and update PHPUnit (PR #849)
+- Get and set methods for OAuth Server Exception payloads. Allow implementer to specify the JSON encode options (PR #719)
+
+### Changed
+- ClientRepository interface will now accept null for the Grant type to improve extensibility options (PR #607)
+- Do not issue an error if key file permissions are 400 or 440 (PR #839)
+- Skip key file creation if the file already exists (PR #845)
+- Change changelog format and update readme
+
+### Removed
+- Support for PHP 5.6
+- Support for version 5.x and 6.x of the library
+
+### Fixed
+- PKCE implementation (PR #744)
+- Set correct redirect URI when validating scopes (PR #840)
+- S256 code challenege method (PR #842)
+- Accept RSA key with CRLF line endings (PR #805)
+
+## [6.1.1] - 2017-12-23
+
+- Removed check on empty scopes
+
+## [6.1.0] - 2017-12-23
+
+- Changed the token type issued by the Implicit Grant to be Bearer instead of bearer. (PR #724)
+- Replaced call to array_key_exists() with the faster isset() on the Implicit Grant. (PR #749)
+- Allow specification of query delimiter character in the Password Grant (PR #801)
+- Add Zend Diactoros library dependency to examples (PR #678)
+- Can set default scope for the authorization endpoint. If no scope is passed during an authorization request, the default scope will be used if set. If not, the server will issue an invalid scope exception (PR #811)
+- Added validation for redirect URIs on the authorization end point to ensure exactly one redirection URI has been passed (PR #573)
+
+## [6.0.2] - 2017-08-03
+
+- An invalid refresh token that can't be decrypted now returns a HTTP 401 error instead of HTTP 400 (Issue #759)
+- Removed chmod from CryptKey and add toggle to disable checking (Issue #776)
+- Fixes invalid code challenge method payload key name (Issue #777)
+
+## [6.0.1] - 2017-07-19
+
+To address feedback from the security release the following change has been made:
+
+- If an RSA key cannot be chmod'ed to 600 then it will now throw a E_USER_NOTICE instead of an exception.
+
+## [6.0.0] - 2017-07-01
+
+- Breaking change: The `AuthorizationServer` constructor now expects an encryption key string instead of a public key
+- Remove support for HHVM
+- Remove support for PHP 5.5
+
+## [5.1.4] - 2017-07-01
+
+- Fixed multiple security vulnerabilities as a result of a security audit paid for by the [Mozilla Secure Open Source Fund](https://wiki.mozilla.org/MOSS/Secure_Open_Source). All users of this library are encouraged to update as soon as possible to this version or version 6.0 or greater.
+	- It is recommended on each `AuthorizationServer` instance you set the `setEncryptionKey()`. This will result in stronger encryption being used. If this method is not set messages will be sent to the defined error handling routines (using `error_log`). Please see the examples and documentation for examples.
+- TravisCI now tests PHP 7.1 (Issue #671)
+- Fix middleware example fatal error (Issue #682)
+- Fix typo in the first README sentence (Issue #690)
+- Corrected DateInterval from 1 min to 1 month (Issue #709)
+
+## [5.1.3] - 2016-10-12
+
+- Fixed WWW-Authenticate header (Issue #669)
+- Increase the recommended RSA key length from 1024 to 2048 bits (Issue #668)
+
+## [5.1.2] - 2016-09-19
+
+- Fixed `finalizeScopes` call (Issue #650)
+
+## [4.1.6] - 2016-09-13
+
+- Less restrictive on Authorization header check (Issue #652)
+
+## [5.1.1] - 2016-07-26
+
+- Improved test suite (Issue #614)
+- Updated docblocks (Issue #616)
+- Replace `array_shift` with `foreach` loop (Issue #621)
+- Allow easy addition of custom fields to Bearer token response (Issue #624)
+- Key file auto-generation from string (Issue #625)
+
+## [5.1.0] - 2016-06-28
+
+- Implemented RFC7636 (Issue #574)
+- Unify middleware exception responses (Issue #578)
+- Updated examples (Issue #589)
+- Ensure state is in access denied redirect (Issue #597)
+- Remove redundant `isExpired()` method from entity interfaces and traits (Issue #600)
+- Added a check for unique access token constraint violation (Issue #601)
+- Look at Authorization header directly for HTTP Basic auth checks (Issue #604)
+- Added catch Runtime exception when parsing JWT string (Issue #605)
+- Allow `paragonie/random_compat` 2.x (Issue #606)
+- Added `indigophp/hash-compat` to Composer suggestions and `require-dev` for PHP 5.5 support
+
+## [5.0.3] - 2016-05-04
+
+- Fix hints in PasswordGrant (Issue #560)
+- Add meaning of `Resource owner` to terminology.md (Issue #561)
+- Use constant for event name instead of explicit string (Issue #563)
+- Remove unused request property (Issue #564)
+- Correct wrong phpdoc (Issue #569)
+- Fixed typo in exception string (Issue #570)
+
+## [5.0.2] - 2016-04-18
+
+- `state` parameter is now correctly returned after implicit grant authorization
+- Small code and docblock improvements
+
+## [5.0.1] - 2016-04-18
+
+- Fixes an issue (#550) whereby it was unclear whether or not to validate a client's secret during a request.
+
+## [5.0.0] - 2016-04-17

 Version 5 is a complete code rewrite.

-* JWT support
-* PSR-7 support
-* Improved exception errors
-* Replace all occurrences of the term "Storage" with "Repository"
-* Simplify repositories
-* Entities conform to interfaces and use traits
-* Auth code grant updated
-    * Allow support for public clients
-    * Add support for #439
-* Client credentials grant updated
-* Password grant updated
-    * Allow support for public clients
-* Refresh token grant updated
-* Implement Implicit grant
-* Bearer token output type
-* Remove MAC token output type
-* Authorization server rewrite
-* Resource server class moved to PSR-7 middleware
-* Tests
-* Much much better documentation
+- Renamed Server class to AuthorizationServer
+- Added ResourceServer class
+- Run unit tests again PHP 5.5.9 as it's the minimum supported version
+- Enable PHPUnit 5.0 support
+- Improved examples and documentation
+- Make it clearer that the implicit grant doesn't support refresh tokens
+- Improved refresh token validation errors
+- Fixed refresh token expiry date

-Changes since RC2:
+## [5.0.0-RC2] - 2016-04-10

-* Renamed Server class to AuthorizationServer
-* Added ResourceServer class
-* Run unit tests again PHP 5.5.9 as it's the minimum supported version
-* Enable PHPUnit 5.0 support
-* Improved examples and documentation
-* Make it clearer that the implicit grant doesn't support refresh tokens
-* Improved refresh token validation errors
-* Fixed refresh token expiry date
+- Allow multiple client redirect URIs (Issue #511)
+- Remove unused mac token interface (Issue #503)
+- Handle RSA key passphrase (Issue #502)
+- Remove access token repository from response types (Issue #501)
+- Remove unnecessary methods from entity interfaces (Issue #490)
+- Ensure incoming JWT hasn't expired (Issue #509)
+- Fix client identifier passed where user identifier is expected (Issue #498)
+- Removed built-in entities; added traits to for quick re-use (Issue #504)
+- Redirect uri is required only if the "redirect_uri" parameter was included in the authorization request (Issue #514)
+- Removed templating for auth code and implicit grants (Issue #499)

-## 5.0.0-RC2 (released 2016-04-10)
-
-Changes since RC1:
-
-* Allow multiple client redirect URIs (Issue #511)
-* Remove unused mac token interface (Issue #503)
-* Handle RSA key passphrase (Issue #502)
-* Remove access token repository from response types (Issue #501)
-* Remove unnecessary methods from entity interfaces (Issue #490)
-* Ensure incoming JWT hasn't expired (Issue #509)
-* Fix client identifier passed where user identifier is expected (Issue #498)
-* Removed built-in entities; added traits to for quick re-use (Issue #504)
-* Redirect uri is required only if the "redirect_uri" parameter was included in the authorization request (Issue #514)
-* Removed templating for auth code and implicit grants (Issue #499)
-
-## 5.0.0-RC1 (release 2016-03-24)
+## [5.0.0-RC1] - 2016-03-24

 Version 5 is a complete code rewrite.

-* JWT support
-* PSR-7 support
-* Improved exception errors
-* Replace all occurrences of the term "Storage" with "Repository"
-* Simplify repositories
-* Entities conform to interfaces and use traits
-* Auth code grant updated
-    * Allow support for public clients
-    * Add support for #439
-* Client credentials grant updated
-* Password grant updated
-    * Allow support for public clients
-* Refresh token grant updated
-* Implement Implicit grant
-* Bearer token output type
-* Remove MAC token output type
-* Authorization server rewrite
-* Resource server class moved to PSR-7 middleware
-* Tests
-* Much much better documentation
+- JWT support
+- PSR-7 support
+- Improved exception errors
+- Replace all occurrences of the term "Storage" with "Repository"
+- Simplify repositories
+- Entities conform to interfaces and use traits
+- Auth code grant updated
+  - Allow support for public clients
+  - Add support for #439
+- Client credentials grant updated
+- Password grant updated
+  - Allow support for public clients
+- Refresh token grant updated
+- Implement Implicit grant
+- Bearer token output type
+- Remove MAC token output type
+- Authorization server rewrite
+- Resource server class moved to PSR-7 middleware
+- Tests
+- Much much better documentation

-## 4.1.5 (released 2016-01-04)
+## [4.1.5] - 2016-01-04

-* Enable Symfony 3.0 support (#412)
+- Enable Symfony 3.0 support (#412)

-## 4.1.4 (released 2015-11-13)
+## [4.1.4] - 2015-11-13

-* Fix for determining access token in header (Issue #328)
-* Refresh tokens are now returned for MAC responses (Issue #356)
-* Added integration list to readme (Issue #341)
-* Expose parameter passed to exceptions (Issue #345)
-* Removed duplicate routing setup code (Issue #346)
-* Docs fix (Issues #347, #360, #380)
-* Examples fix (Issues #348, #358)
-* Fix typo in docblock (Issue #352)
-* Improved timeouts for MAC tokens (Issue #364)
-* `hash_hmac()` should output raw binary data, not hexits (Issue #370)
-* Improved regex for matching all Base64 characters (Issue #371)
-* Fix incorrect signature parameter (Issue #372)
-* AuthCodeGrant and RefreshTokenGrant don't require client_secret (Issue #377)
-* Added priority argument to event listener (Issue #388)
+- Fix for determining access token in header (Issue #328)
+- Refresh tokens are now returned for MAC responses (Issue #356)
+- Added integration list to readme (Issue #341)
+- Expose parameter passed to exceptions (Issue #345)
+- Removed duplicate routing setup code (Issue #346)
+- Docs fix (Issues #347, #360, #380)
+- Examples fix (Issues #348, #358)
+- Fix typo in docblock (Issue #352)
+- Improved timeouts for MAC tokens (Issue #364)
+- `hash_hmac()` should output raw binary data, not hexits (Issue #370)
+- Improved regex for matching all Base64 characters (Issue #371)
+- Fix incorrect signature parameter (Issue #372)
+- AuthCodeGrant and RefreshTokenGrant don't require client_secret (Issue #377)
+- Added priority argument to event listener (Issue #388)

-## 4.1.3 (released 2015-03-22)
+## [4.1.3] - 2015-03-22

-* Docblock, namespace and inconsistency fixes (Issue #303)
-* Docblock type fix (Issue #310)
-* Example bug fix (Issue #300)
-* Updated league/event to ~2.1 (Issue #311)
-* Fixed missing session scope (Issue #319)
-* Updated interface docs (Issue #323)
-* `.travis.yml` updates
+- Docblock, namespace and inconsistency fixes (Issue #303)
+- Docblock type fix (Issue #310)
+- Example bug fix (Issue #300)
+- Updated league/event to ~2.1 (Issue #311)
+- Fixed missing session scope (Issue #319)
+- Updated interface docs (Issue #323)
+- `.travis.yml` updates

-## 4.1.2 (released 2015-01-01)
+## [4.1.2] - 2015-01-01

-* Remove side-effects in hash_equals() implementation (Issue #290)
+- Remove side-effects in hash_equals() implementation (Issue #290)

-## 4.1.1 (released 2014-12-31)
+## [4.1.1] - 2014-12-31

-* Changed `symfony/http-foundation` dependency version to `~2.4` so package can be installed in Laravel `4.1.*`
+- Changed `symfony/http-foundation` dependency version to `~2.4` so package can be installed in Laravel `4.1.*`

-## 4.1.0 (released 2014-12-27)
+## [4.1.0] - 2014-12-27

-* Added MAC token support (Issue #158)
-* Fixed example init code (Issue #280)
-* Toggle refresh token rotation (Issue #286)
-* Docblock fixes
+- Added MAC token support (Issue #158)
+- Fixed example init code (Issue #280)
+- Toggle refresh token rotation (Issue #286)
+- Docblock fixes

-## 4.0.5 (released 2014-12-15)
+## [4.0.5] - 2014-12-15

-* Prevent duplicate session in auth code grant (Issue #282)
+- Prevent duplicate session in auth code grant (Issue #282)

-## 4.0.4 (released 2014-12-03)
+## [4.0.4] - 2014-12-03

-* Ensure refresh token hasn't expired (Issue #270)
+- Ensure refresh token hasn't expired (Issue #270)

-## 4.0.3 (released 2014-12-02)
+## [4.0.3] - 2014-12-02

-* Fix bad type hintings (Issue #267)
-* Do not forget to set the expire time (Issue #268)
+- Fix bad type hintings (Issue #267)
+- Do not forget to set the expire time (Issue #268)

-## 4.0.2 (released 2014-11-21)
+## [4.0.2] - 2014-11-21

-* Improved interfaces (Issue #255)
-* Learnt how to spell delimiter and so `getScopeDelimiter()` and `setScopeDelimiter()` methods have been renamed
-* Docblock improvements (Issue #254)
+- Improved interfaces (Issue #255)
+- Learnt how to spell delimiter and so `getScopeDelimiter()` and `setScopeDelimiter()` methods have been renamed
+- Docblock improvements (Issue #254)

-## 4.0.1 (released 2014-11-09)
+## [4.0.1] - 2014-11-09

-* Alias the master branch in composer.json (Issue #243)
-* Numerous PHP CodeSniffer fixes (Issue #244)
-* .travis.yml update (Issue #245)
-* The getAccessToken method should return an AccessTokenEntity object instead of a string in ResourceServer.php (#246)
+- Alias the master branch in composer.json (Issue #243)
+- Numerous PHP CodeSniffer fixes (Issue #244)
+- .travis.yml update (Issue #245)
+- The getAccessToken method should return an AccessTokenEntity object instead of a string in ResourceServer.php (#246)

-## 4.0.0 (released 2014-11-08)
+## [4.0.0] - 2014-11-08

-* Complete rewrite
-* Check out the documentation - [http://oauth2.thephpleague.com](http://oauth2.thephpleague.com)
+- Complete rewrite
+- Check out the documentation - [http://oauth2.thephpleague.com](http://oauth2.thephpleague.com)

-## 3.2.0 (released 2014-04-16)
+## [3.2.0] - 2014-04-16

-* Added the ability to change the algorithm that is used to generate the token strings (Issue #151)
+- Added the ability to change the algorithm that is used to generate the token strings (Issue #151)

-## 3.1.2 (released 2014-02-26)
+## [3.1.2] - 2014-02-26

-* Support Authorization being an environment variable. [See more](http://fortrabbit.com/docs/essentials/quirks-and-constraints#authorization-header)
+- Support Authorization being an environment variable. [See more](http://fortrabbit.com/docs/essentials/quirks-and-constraints#authorization-header)

-## 3.1.1 (released 2013-12-05)
+## [3.1.1] - 2013-12-05

-* Normalize headers when `getallheaders()` is available (Issues #108 and #114)
+- Normalize headers when `getallheaders()` is available (Issues #108 and #114)

-## 3.1.0 (released 2013-12-05)
+## [3.1.0] - 2013-12-05

-* No longer necessary to inject the authorisation server into a grant, the server will inject itself
-* Added test for 1419ba8cdcf18dd034c8db9f7de86a2594b68605
+- No longer necessary to inject the authorisation server into a grant, the server will inject itself
+- Added test for 1419ba8cdcf18dd034c8db9f7de86a2594b68605

-## 3.0.1 (released 2013-12-02)
+## [3.0.1] - 2013-12-02

-* Forgot to tell TravisCI from testing PHP 5.3
+- Forgot to tell TravisCI from testing PHP 5.3

-## 3.0.0 (released 2013-12-02)
+## [3.0.0] - 2013-12-02

-* Fixed spelling of Implicit grant class (Issue #84)
-* Travis CI now tests for PHP 5.5
-* Fixes for checking headers for resource server (Issues #79 and #)
-* The word "bearer" now has a capital "B" in JSON output to match OAuth 2.0 spec
-* All grants no longer remove old sessions by default
-* All grants now support custom access token TTL (Issue #92)
-* All methods which didn't before return a value now return `$this` to support method chaining
-* Removed the build in DB providers - these will be put in their own repos to remove baggage in the main repository
-* Removed support for PHP 5.3 because this library now uses traits and will use other modern PHP features going forward
-* Moved some grant related functions into a trait to reduce duplicate code
+- Fixed spelling of Implicit grant class (Issue #84)
+- Travis CI now tests for PHP 5.5
+- Fixes for checking headers for resource server (Issues #79 and #)
+- The word "bearer" now has a capital "B" in JSON output to match OAuth 2.0 spec
+- All grants no longer remove old sessions by default
+- All grants now support custom access token TTL (Issue #92)
+- All methods which didn't before return a value now return `$this` to support method chaining
+- Removed the build in DB providers - these will be put in their own repos to remove baggage in the main repository
+- Removed support for PHP 5.3 because this library now uses traits and will use other modern PHP features going forward
+- Moved some grant related functions into a trait to reduce duplicate code

-## 2.1.1 (released 2013-06-02)
+## [2.1.1] - 2013-06-02

-* Added conditional `isValid()` flag to check for Authorization header only (thanks @alexmcroberts)
-* Fixed semantic meaning of `requireScopeParam()` and `requireStateParam()` by changing their default value to true
-* Updated some duff docblocks
-* Corrected array key call in Resource.php (Issue #63)
+- Added conditional `isValid()` flag to check for Authorization header only (thanks @alexmcroberts)
+- Fixed semantic meaning of `requireScopeParam()` and `requireStateParam()` by changing their default value to true
+- Updated some duff docblocks
+- Corrected array key call in Resource.php (Issue #63)

-## 2.1 (released 2013-05-10)
+## [2.1.0] - 2013-05-10

-* Moved zetacomponents/database to "suggest" in composer.json. If you rely on this feature you now need to include " zetacomponents/database" into "require" key in your own composer.json. (Issue #51)
-* New method in Refresh grant called `rotateRefreshTokens()`. Pass in `true` to issue a new refresh token each time an access token is refreshed. This parameter needs to be set to true in order to request reduced scopes with the new access token. (Issue #47)
-* Rename `key` column in oauth_scopes table to `scope` as `key` is a reserved SQL word. (Issue #45)
-* The `scope` parameter is no longer required by default as per the RFC. (Issue #43)
-* You can now set multiple default scopes by passing an array into `setDefaultScope()`. (Issue #42)
-* The password and client credentials grants now allow for multiple sessions per user. (Issue #32)
-* Scopes associated to authorization codes are not held in their own table (Issue #44)
-* Database schema updates.
+- Moved zetacomponents/database to "suggest" in composer.json. If you rely on this feature you now need to include " zetacomponents/database" into "require" key in your own composer.json. (Issue #51)
+- New method in Refresh grant called `rotateRefreshTokens()`. Pass in `true` to issue a new refresh token each time an access token is refreshed. This parameter needs to be set to true in order to request reduced scopes with the new access token. (Issue #47)
+- Rename `key` column in oauth_scopes table to `scope` as `key` is a reserved SQL word. (Issue #45)
+- The `scope` parameter is no longer required by default as per the RFC. (Issue #43)
+- You can now set multiple default scopes by passing an array into `setDefaultScope()`. (Issue #42)
+- The password and client credentials grants now allow for multiple sessions per user. (Issue #32)
+- Scopes associated to authorization codes are not held in their own table (Issue #44)
+- Database schema updates.

-## 2.0.5 (released 2013-05-09)
+## [2.0.5] - 2013-05-09

-* Fixed `oauth_session_token_scopes` table primary key
-* Removed `DEFAULT ''` that has slipped into some tables
-* Fixed docblock for `SessionInterface::associateRefreshToken()`
+- Fixed `oauth_session_token_scopes` table primary key
+- Removed `DEFAULT ''` that has slipped into some tables
+- Fixed docblock for `SessionInterface::associateRefreshToken()`

-## 2.0.4 (released 2013-05-09)
+## [2.0.4] - 2013-05-09

-* Renamed primary key in oauth_client_endpoints table
-* Adding missing column to oauth_session_authcodes
-* SECURITY FIX: A refresh token should be bound to a client ID
+- Renamed primary key in oauth_client_endpoints table
+- Adding missing column to oauth_session_authcodes

-## 2.0.3 (released 2013-05-08)
+### Security
+- A refresh token should be bound to a client ID

-* Fixed a link to code in composer.json
+## [2.0.3] - 2013-05-08

-## 2.0.2 (released 2013-05-08)
+- Fixed a link to code in composer.json

-* Updated README with wiki guides
-* Removed `null` as default parameters in some methods in the storage interfaces
-* Fixed license copyright
+## [2.0.2] - 2013-05-08

-## 2.0.0 (released 2013-05-08)
+- Updated README with wiki guides
+- Removed `null` as default parameters in some methods in the storage interfaces
+- Fixed license copyright
+
+## [2.0.0] - 2013-05-08

 **If you're upgrading from v1.0.8 there are lots of breaking changes**

-* Rewrote the session storage interface from scratch so methods are more obvious
-* Included a PDO driver which implements the storage interfaces so the library is more "get up and go"
-* Further normalised the database structure so all sessions no longer contain infomation related to authorization grant (which may or may not be enabled)
-* A session can have multiple associated access tokens
-* Individual grants can have custom expire times for access tokens
-* Authorization codes now have a TTL of 10 minutes by default (can be manually set)
-* Refresh tokens now have a TTL of one week by default (can be manually set)
-* The client credentials grant will no longer gives out refresh tokens as per the specification
+- Rewrote the session storage interface from scratch so methods are more obvious
+- Included a PDO driver which implements the storage interfaces so the library is more "get up and go"
+- Further normalised the database structure so all sessions no longer contain infomation related to authorization grant (which may or may not be enabled)
+- A session can have multiple associated access tokens
+- Individual grants can have custom expire times for access tokens
+- Authorization codes now have a TTL of 10 minutes by default (can be manually set)
+- Refresh tokens now have a TTL of one week by default (can be manually set)
+- The client credentials grant will no longer gives out refresh tokens as per the specification

-## 1.0.8 (released 2013-03-18)
+## [1.0.8] - 2013-03-18

-* Fixed check for required state parameter
-* Fixed check that user's credentials are correct in Password grant
+- Fixed check for required state parameter
+- Fixed check that user's credentials are correct in Password grant

-## 1.0.7 (released 2013-03-04)
+## [1.0.7] - 2013-03-04

-* Added method `requireStateParam()`
-* Added method `requireScopeParam()`
+- Added method `requireStateParam()`
+- Added method `requireScopeParam()`

-## 1.0.6 (released 2013-02-22)
+## [1.0.6] - 2013-02-22

-* Added links to tutorials in the README
-* Added missing `state` parameter request to the `checkAuthoriseParams()` method.
+- Added links to tutorials in the README
+- Added missing `state` parameter request to the `checkAuthoriseParams()` method.

-## 1.0.5 (released 2013-02-21)
+## [1.0.5] - 2013-02-21

-* Fixed the SQL example for SessionInterface::getScopes()
+- Fixed the SQL example for SessionInterface::getScopes()

-## 1.0.3 (released 2013-02-20)
+## [1.0.3] - 2013-02-20

-* Changed all instances of the "authentication server" to "authorization server"
+- Changed all instances of the "authentication server" to "authorization server"

-## 1.0.2 (released 2013-02-20)
+## [1.0.2] - 2013-02-20

-* Fixed MySQL create table order
-* Fixed version number in composer.json
+- Fixed MySQL create table order
+- Fixed version number in composer.json

-## 1.0.1 (released 2013-02-19)
+## [1.0.1] - 2013-02-19

-* Updated AuthServer.php to use `self::getParam()`
+- Updated AuthServer.php to use `self::getParam()`

-## 1.0.0 (released 2013-02-15)
+## 1.0.0 - 2013-02-15

-* First major release
+- First major release
+
+[Unreleased]: https://github.com/thephpleague/oauth2-server/compare/7.3.3...HEAD
+[7.3.3]: https://github.com/thephpleague/oauth2-server/compare/7.3.2...7.3.3
+[7.3.2]: https://github.com/thephpleague/oauth2-server/compare/7.3.1...7.3.2
+[7.3.1]: https://github.com/thephpleague/oauth2-server/compare/7.3.0...7.3.1
+[7.3.0]: https://github.com/thephpleague/oauth2-server/compare/7.2.0...7.3.0
+[7.2.0]: https://github.com/thephpleague/oauth2-server/compare/7.1.1...7.2.0
+[7.1.1]: https://github.com/thephpleague/oauth2-server/compare/7.1.0...7.1.1
+[7.1.0]: https://github.com/thephpleague/oauth2-server/compare/7.0.0...7.1.0
+[7.0.0]: https://github.com/thephpleague/oauth2-server/compare/6.1.1...7.0.0
+[6.1.1]: https://github.com/thephpleague/oauth2-server/compare/6.0.0...6.1.1
+[6.1.0]: https://github.com/thephpleague/oauth2-server/compare/6.0.2...6.1.0
+[6.0.2]: https://github.com/thephpleague/oauth2-server/compare/6.0.1...6.0.2
+[6.0.1]: https://github.com/thephpleague/oauth2-server/compare/6.0.0...6.0.1
+[6.0.0]: https://github.com/thephpleague/oauth2-server/compare/5.1.4...6.0.0
+[5.1.4]: https://github.com/thephpleague/oauth2-server/compare/5.1.3...5.1.4
+[5.1.3]: https://github.com/thephpleague/oauth2-server/compare/5.1.2...5.1.3
+[5.1.2]: https://github.com/thephpleague/oauth2-server/compare/5.1.1...5.1.2
+[5.1.1]: https://github.com/thephpleague/oauth2-server/compare/5.1.0...5.1.1
+[5.1.0]: https://github.com/thephpleague/oauth2-server/compare/5.0.2...5.1.0
+[5.0.3]: https://github.com/thephpleague/oauth2-server/compare/5.0.3...5.0.2
+[5.0.2]: https://github.com/thephpleague/oauth2-server/compare/5.0.1...5.0.2
+[5.0.1]: https://github.com/thephpleague/oauth2-server/compare/5.0.0...5.0.1
+[5.0.0]: https://github.com/thephpleague/oauth2-server/compare/5.0.0-RC2...5.0.0
+[5.0.0-RC2]: https://github.com/thephpleague/oauth2-server/compare/5.0.0-RC1...5.0.0-RC2
+[5.0.0-RC1]: https://github.com/thephpleague/oauth2-server/compare/4.1.5...5.0.0-RC1
+[4.1.7]: https://github.com/thephpleague/oauth2-server/compare/4.1.6...4.1.7
+[4.1.6]: https://github.com/thephpleague/oauth2-server/compare/4.1.5...4.1.6
+[4.1.5]: https://github.com/thephpleague/oauth2-server/compare/4.1.4...4.1.5
+[4.1.4]: https://github.com/thephpleague/oauth2-server/compare/4.1.3...4.1.4
+[4.1.3]: https://github.com/thephpleague/oauth2-server/compare/4.1.2...4.1.3
+[4.1.2]: https://github.com/thephpleague/oauth2-server/compare/4.1.1...4.1.2
+[4.1.1]: https://github.com/thephpleague/oauth2-server/compare/4.0.0...4.1.1
+[4.1.0]: https://github.com/thephpleague/oauth2-server/compare/4.0.5...4.1.0
+[4.0.5]: https://github.com/thephpleague/oauth2-server/compare/4.0.4...4.0.5
+[4.0.4]: https://github.com/thephpleague/oauth2-server/compare/4.0.3...4.0.4
+[4.0.3]: https://github.com/thephpleague/oauth2-server/compare/4.0.2...4.0.3
+[4.0.2]: https://github.com/thephpleague/oauth2-server/compare/4.0.1...4.0.2
+[4.0.1]: https://github.com/thephpleague/oauth2-server/compare/4.0.0...4.0.1
+[4.0.0]: https://github.com/thephpleague/oauth2-server/compare/3.2.0...4.0.0
+[3.2.0]: https://github.com/thephpleague/oauth2-server/compare/3.1.2...3.2.0
+[3.1.2]: https://github.com/thephpleague/oauth2-server/compare/3.1.1...3.1.2
+[3.1.1]: https://github.com/thephpleague/oauth2-server/compare/3.1.0...3.1.1
+[3.1.0]: https://github.com/thephpleague/oauth2-server/compare/3.0.1...3.1.0
+[3.0.1]: https://github.com/thephpleague/oauth2-server/compare/3.0.0...3.0.1
+[3.0.0]: https://github.com/thephpleague/oauth2-server/compare/2.1.1...3.0.0
+[2.1.1]: https://github.com/thephpleague/oauth2-server/compare/2.1.0...2.1.1
+[2.1.0]: https://github.com/thephpleague/oauth2-server/compare/2.0.5...2.1.0
+[2.0.5]: https://github.com/thephpleague/oauth2-server/compare/2.0.4...2.0.5
+[2.0.4]: https://github.com/thephpleague/oauth2-server/compare/2.0.3...2.0.4
+[2.0.3]: https://github.com/thephpleague/oauth2-server/compare/2.0.2...2.0.3
+[2.0.2]: https://github.com/thephpleague/oauth2-server/compare/2.0.0...2.0.2
+[2.0.0]: https://github.com/thephpleague/oauth2-server/compare/1.0.8...2.0.0
+[1.0.8]: https://github.com/thephpleague/oauth2-server/compare/1.0.7...1.0.8
+[1.0.7]: https://github.com/thephpleague/oauth2-server/compare/1.0.6...1.0.7
+[1.0.6]: https://github.com/thephpleague/oauth2-server/compare/1.0.5...1.0.6
+[1.0.5]: https://github.com/thephpleague/oauth2-server/compare/1.0.3...1.0.5
+[1.0.3]: https://github.com/thephpleague/oauth2-server/compare/1.0.2...1.0.3
+[1.0.2]: https://github.com/thephpleague/oauth2-server/compare/1.0.1...1.0.2
+[1.0.1]: https://github.com/thephpleague/oauth2-server/compare/1.0.0...1.0.1
--- a/CODE_OF_CONDUCT.md
+++ b/CODE_OF_CONDUCT.md
@@ -0,0 +1,73 @@
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+In the interest of fostering an open and welcoming environment, we as
+contributors and maintainers pledge to making participation in our project and
+our community a harassment-free experience for everyone, regardless of age, body
+size, disability, ethnicity, gender identity and expression, level of experience,
+education, socio-economic status, nationality, personal appearance, race,
+religion, or sexual identity and orientation.
+
+## Our Standards
+
+Examples of behavior that contributes to creating a positive environment
+include:
+
+* Using welcoming and inclusive language
+* Being respectful of differing viewpoints and experiences
+* Gracefully accepting constructive criticism
+* Focusing on what is best for the community
+* Showing empathy towards other community members
+
+Examples of unacceptable behavior by participants include:
+
+* The use of sexualized language or imagery and unwelcome sexual attention or
+  advances
+* Trolling, insulting/derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or electronic
+  address, without explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+  professional setting
+
+## Our Responsibilities
+
+Project maintainers are responsible for clarifying the standards of acceptable
+behavior and are expected to take appropriate and fair corrective action in
+response to any instances of unacceptable behavior.
+
+Project maintainers have the right and responsibility to remove, edit, or
+reject comments, commits, code, wiki edits, issues, and other contributions
+that are not aligned to this Code of Conduct, or to ban temporarily or
+permanently any contributor for other behaviors that they deem inappropriate,
+threatening, offensive, or harmful.
+
+## Scope
+
+This Code of Conduct applies both within project spaces and in public spaces
+when an individual is representing the project or its community. Examples of
+representing a project or community include using an official project e-mail
+address, posting via an official social media account, or acting as an appointed
+representative at an online or offline event. Representation of a project may be
+further defined and clarified by project maintainers.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported by contacting the project team at andrew@noexceptions.io. All
+complaints will be reviewed and investigated and will result in a response that
+is deemed necessary and appropriate to the circumstances. The project team is
+obligated to maintain confidentiality with regard to the reporter of an incident.
+Further details of specific enforcement policies may be posted separately.
+
+Project maintainers who do not follow or enforce the Code of Conduct in good
+faith may face temporary or permanent repercussions as determined by other
+members of the project's leadership.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4,
+available at https://www.contributor-covenant.org/version/1/4/code-of-conduct.html
+
+[homepage]: https://www.contributor-covenant.org
--- a/CONDUCT.md
+++ b/CONDUCT.md
@@ -1,22 +0,0 @@
-# Contributor Code of Conduct
-
-As contributors and maintainers of this project, and in the interest of fostering an open and welcoming community, we pledge to respect all people who contribute through reporting issues, posting feature requests, updating documentation, submitting pull requests or patches, and other activities.
-
-We are committed to making participation in this project a harassment-free experience for everyone, regardless of level of experience, gender, gender identity and expression, sexual orientation, disability, personal appearance, body size, race, ethnicity, age, religion, or nationality.
-
-Examples of unacceptable behavior by participants include:
-
-* The use of sexualized language or imagery
-* Personal attacks
-* Trolling or insulting/derogatory comments
-* Public or private harassment
-* Publishing other's private information, such as physical or electronic addresses, without explicit permission
-* Other unethical or unprofessional conduct.
-
-Project maintainers have the right and responsibility to remove, edit, or reject comments, commits, code, wiki edits, issues, and other contributions that are not aligned to this Code of Conduct. By adopting this Code of Conduct, project maintainers commit themselves to fairly and consistently applying these principles to every aspect of managing this project. Project maintainers who do not follow or enforce the Code of Conduct may be permanently removed from the project team.
-
-This code of conduct applies both within project spaces and in public spaces when an individual is representing the project or its community in a direct capacity. Personal views, beliefs and values of individuals do not necessarily reflect those of the organisation or affiliated individuals and organisations.
-
-Instances of abusive, harassing, or otherwise unacceptable behavior may be reported by opening an issue or contacting one or more of the project maintainers.
-
-This Code of Conduct is adapted from the [Contributor Covenant](http://contributor-covenant.org), version 1.2.0, available at [http://contributor-covenant.org/version/1/2/0/](http://contributor-covenant.org/version/1/2/0/)
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -1,7 +1,7 @@
 Thanks for contributing to this project.


-**Please submit your pull request against the `develop` branch only.**
+**Please submit your pull request against the `master` branch only.**


 Please ensure that you run `phpunit` from the project root after you've made any changes.
--- a/README.md
+++ b/README.md
@@ -6,10 +6,11 @@
 [![Coverage Status](https://img.shields.io/scrutinizer/coverage/g/thephpleague/oauth2-server.svg?style=flat-square)](https://scrutinizer-ci.com/g/thephpleague/oauth2-server/code-structure)
 [![Quality Score](https://img.shields.io/scrutinizer/g/thephpleague/oauth2-server.svg?style=flat-square)](https://scrutinizer-ci.com/g/thephpleague/oauth2-server)
 [![Total Downloads](https://img.shields.io/packagist/dt/league/oauth2-server.svg?style=flat-square)](https://packagist.org/packages/league/oauth2-server)
+[![PHPStan](https://img.shields.io/badge/PHPStan-enabled-brightgreen.svg?style=flat-square)](https://github.com/phpstan/phpstan)

-`league/oauth2-server` is a a standards compliant implementation of an [OAuth 2.0](https://tools.ietf.org/html/rfc6749) authorization server written in PHP which makes working with OAuth 2.0 trivial. You can easily configure an OAuth 2.0 server to protect your API with access tokens, or allow clients to request new access tokens and refresh them.
+`league/oauth2-server` is a standards compliant implementation of an [OAuth 2.0](https://tools.ietf.org/html/rfc6749) authorization server written in PHP which makes working with OAuth 2.0 trivial. You can easily configure an OAuth 2.0 server to protect your API with access tokens, or allow clients to request new access tokens and refresh them.

-It supports out of the box the following grants:
+Out of the box it supports the following grants:

 * Authorization code grant
 * Implicit grant
@@ -30,25 +31,54 @@ This library was created by Alex Bilbie. Find him on Twitter at [@alexbilbie](ht

 The following versions of PHP are supported:

-* PHP 5.5 (>=5.5.9)
-* PHP 5.6
 * PHP 7.0
-* HHVM
+* PHP 7.1
+* PHP 7.2
+* PHP 7.3

 The `openssl` extension is also required.

+All HTTP messages passed to the server should be [PSR-7 compliant](https://www.php-fig.org/psr/psr-7/). This ensures interoperability with other packages and frameworks.
+
+## Installation
+
+```
+composer require league/oauth2-server
+```
+
 ## Documentation

-The library documentation can be found at [https://oauth2.thephpleague.com](https://oauth2.thephpleague.com). 
+The library documentation can be found at [https://oauth2.thephpleague.com](https://oauth2.thephpleague.com).
 You can contribute to the documentation in the [gh-pages branch](https://github.com/thephpleague/oauth2-server/tree/gh-pages/).

+## Testing
+
+The library uses [PHPUnit](https://phpunit.de/) for unit tests and [PHPStan](https://github.com/phpstan/phpstan) for static analysis of the code.
+
+```
+vendor/bin/phpunit
+vendor/bin/phpstan analyse -l 7 -c phpstan.neon src tests
+```
+
+## Continous Integration
+
+We use [Travis CI](https://travis-ci.org/), [Scrutinizer](https://scrutinizer-ci.com/), and [StyleCI](https://styleci.io/) for continuous integration. Check out [our](https://github.com/thephpleague/oauth2-server/blob/master/.travis.yml) [configuration](https://github.com/thephpleague/oauth2-server/blob/master/.scrutinizer.yml) [files](https://github.com/thephpleague/oauth2-server/blob/master/.styleci.yml) if you'd like to know more.
+
+## Community Integrations
+
+* [Drupal](https://www.drupal.org/project/simple_oauth)
+* [Laravel Passport](https://github.com/laravel/passport)
+* [OAuth 2 Server for CakePHP 3](https://github.com/uafrica/oauth-server)
+* [OAuth 2 Server for Expressive](https://github.com/zendframework/zend-expressive-authentication-oauth2)
+* [Trikoder OAuth 2 Bundle (Symfony)](https://github.com/trikoder/oauth2-bundle)
+
 ## Changelog

-[See the project releases page](https://github.com/thephpleague/oauth2-server/releases)
+See the [project changelog](https://github.com/thephpleague/oauth2-server/blob/master/CHANGELOG.md)

 ## Contributing

-Please see [CONTRIBUTING.md](https://github.com/thephpleague/oauth2-server/blob/master/CONTRIBUTING.md) and [CONDUCT.md](https://github.com/thephpleague/oauth2-server/blob/master/CONDUCT.md) for details.
+Contributions are always welcome. Please see [CONTRIBUTING.md](https://github.com/thephpleague/oauth2-server/blob/master/CONTRIBUTING.md) and [CODE_OF_CONDUCT.md](https://github.com/thephpleague/oauth2-server/blob/master/CODE_OF_CONDUCT.md) for details.

 ## Support

@@ -70,8 +100,14 @@ This package is released under the MIT License. See the bundled [LICENSE](https:

 ## Credits

-This code is principally developed and maintained by [Alex Bilbie](https://twitter.com/alexbilbie).
+This code is principally developed and maintained by [Andy Millington](https://twitter.com/Sephster) and [Simon Hamp](https://twitter.com/simonhamp).

-Special thanks to [all of these awesome contributors](https://github.com/thephpleague/oauth2-server/contributors)
+Between 2012 and 2017 this library was developed and maintained by [Alex Bilbie](https://alexbilbie.com/).
+
+PHP OAuth 2.0 Server is one of many packages provided by The PHP League. To find out more, please visit [our website](https://thephpleague.com).
+
+Special thanks to [all of these awesome contributors](https://github.com/thephpleague/oauth2-server/contributors).
+
+Additional thanks go to the [Mozilla Secure Open Source Fund](https://wiki.mozilla.org/MOSS/Secure_Open_Source) for funding a security audit of this library.

 The initial code was developed as part of the [Linkey](http://linkey.blogs.lincoln.ac.uk) project which was funded by [JISC](http://jisc.ac.uk) under the Access and Identity Management programme.
--- a/composer.json
+++ b/composer.json
@@ -4,17 +4,20 @@
    "homepage": "https://oauth2.thephpleague.com/",
    "license": "MIT",
    "require": {
-        "php": ">=5.5.9",
+        "php": ">=7.0.0",
        "ext-openssl": "*",
        "league/event": "^2.1",
-        "lcobucci/jwt": "^3.1",
-        "paragonie/random_compat": "^1.1 || ^2.0",
-        "psr/http-message": "^1.0"
+        "lcobucci/jwt": "^3.2.2",
+        "psr/http-message": "^1.0.1",
+        "defuse/php-encryption": "^2.1"
    },
    "require-dev": {
-        "phpunit/phpunit": "^4.8 || ^5.0",
-        "zendframework/zend-diactoros": "^1.0",
-        "indigophp/hash-compat": "^1.1"
+        "phpunit/phpunit": "^6.3 || ^7.0",
+        "zendframework/zend-diactoros": "^1.3.2",
+        "phpstan/phpstan": "^0.9.2",
+        "phpstan/phpstan-phpunit": "^0.9.4",
+        "phpstan/phpstan-strict-rules": "^0.9.0",
+        "roave/security-advisories": "dev-master"
    },
    "repositories": [
        {
@@ -44,6 +47,12 @@
            "email": "hello@alexbilbie.com",
            "homepage": "http://www.alexbilbie.com",
            "role": "Developer"
+        },
+        {
+            "name": "Andy Millington",
+            "email": "andrew@noexceptions.io",
+            "homepage": "https://www.noexceptions.io",
+            "role": "Developer"
        }
    ],
    "replace": {
@@ -59,13 +68,5 @@
        "psr-4": {
            "LeagueTests\\": "tests/"
        }
-    },
-    "extra": {
-        "branch-alias": {
-            "dev-V5-WIP": "5.0-dev"
-        }
-    },
-    "suggest": {
-        "indigophp/hash-compat": "Polyfill for hash_equals function for PHP 5.5"
    }
 }
--- a/examples/README.md
+++ b/examples/README.md
@@ -3,7 +3,7 @@
 ## Installation

 0. Run `composer install` in this directory to install dependencies
-0. Create a private key `openssl genrsa -out private.key 1024`
+0. Create a private key `openssl genrsa -out private.key 2048`
 0. Create a public key `openssl rsa -in private.key -pubout > public.key`
 0. `cd` into the public directory
 0. Start a PHP server `php -S localhost:4444`
--- a/examples/composer.json
+++ b/examples/composer.json
@@ -1,12 +1,13 @@
 {
    "require": {
-        "slim/slim": "3.0.*"
+        "slim/slim": "^3.0.0"
    },
    "require-dev": {
        "league/event": "^2.1",
-        "lcobucci/jwt": "^3.1",
-        "paragonie/random_compat": "^1.1",
-        "psr/http-message": "^1.0"
+        "lcobucci/jwt": "^3.2",
+        "psr/http-message": "^1.0",
+        "defuse/php-encryption": "^2.2",
+        "zendframework/zend-diactoros": "^2.0.0"
    },
    "autoload": {
        "psr-4": {
--- a/examples/composer.lock
+++ b/examples/composer.lock
@@ -4,23 +4,25 @@
        "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
        "This file is @generated automatically"
    ],
-    "hash": "48bcb7a3514d7c7f271c554ba1440124",
-    "content-hash": "e41be75973527cb9d63f27ad14ac8624",
+    "content-hash": "97f2878428e37d1d8e5418cc85cbfa3d",
    "packages": [
        {
            "name": "container-interop/container-interop",
-            "version": "1.1.0",
+            "version": "1.2.0",
            "source": {
                "type": "git",
                "url": "https://github.com/container-interop/container-interop.git",
-                "reference": "fc08354828f8fd3245f77a66b9e23a6bca48297e"
+                "reference": "79cbf1341c22ec75643d841642dd5d6acd83bdb8"
            },
            "dist": {
                "type": "zip",
-                "url": "https://api.github.com/repos/container-interop/container-interop/zipball/fc08354828f8fd3245f77a66b9e23a6bca48297e",
-                "reference": "fc08354828f8fd3245f77a66b9e23a6bca48297e",
+                "url": "https://api.github.com/repos/container-interop/container-interop/zipball/79cbf1341c22ec75643d841642dd5d6acd83bdb8",
+                "reference": "79cbf1341c22ec75643d841642dd5d6acd83bdb8",
                "shasum": ""
            },
+            "require": {
+                "psr/container": "^1.0"
+            },
            "type": "library",
            "autoload": {
                "psr-4": {
@@ -32,25 +34,29 @@
                "MIT"
            ],
            "description": "Promoting the interoperability of container objects (DIC, SL, etc.)",
-            "time": "2014-12-30 15:22:37"
+            "homepage": "https://github.com/container-interop/container-interop",
+            "time": "2017-02-14T19:40:03+00:00"
        },
        {
            "name": "nikic/fast-route",
-            "version": "v0.6.0",
+            "version": "v1.3.0",
            "source": {
                "type": "git",
                "url": "https://github.com/nikic/FastRoute.git",
-                "reference": "31fa86924556b80735f98b294a7ffdfb26789f22"
+                "reference": "181d480e08d9476e61381e04a71b34dc0432e812"
            },
            "dist": {
                "type": "zip",
-                "url": "https://api.github.com/repos/nikic/FastRoute/zipball/31fa86924556b80735f98b294a7ffdfb26789f22",
-                "reference": "31fa86924556b80735f98b294a7ffdfb26789f22",
+                "url": "https://api.github.com/repos/nikic/FastRoute/zipball/181d480e08d9476e61381e04a71b34dc0432e812",
+                "reference": "181d480e08d9476e61381e04a71b34dc0432e812",
                "shasum": ""
            },
            "require": {
                "php": ">=5.4.0"
            },
+            "require-dev": {
+                "phpunit/phpunit": "^4.8.35|~5.7"
+            },
            "type": "library",
            "autoload": {
                "psr-4": {
@@ -75,29 +81,33 @@
                "router",
                "routing"
            ],
-            "time": "2015-06-18 19:15:47"
+            "time": "2018-02-13T20:26:39+00:00"
        },
        {
            "name": "pimple/pimple",
-            "version": "v3.0.2",
+            "version": "v3.2.3",
            "source": {
                "type": "git",
                "url": "https://github.com/silexphp/Pimple.git",
-                "reference": "a30f7d6e57565a2e1a316e1baf2a483f788b258a"
+                "reference": "9e403941ef9d65d20cba7d54e29fe906db42cf32"
            },
            "dist": {
                "type": "zip",
-                "url": "https://api.github.com/repos/silexphp/Pimple/zipball/a30f7d6e57565a2e1a316e1baf2a483f788b258a",
-                "reference": "a30f7d6e57565a2e1a316e1baf2a483f788b258a",
+                "url": "https://api.github.com/repos/silexphp/Pimple/zipball/9e403941ef9d65d20cba7d54e29fe906db42cf32",
+                "reference": "9e403941ef9d65d20cba7d54e29fe906db42cf32",
                "shasum": ""
            },
            "require": {
-                "php": ">=5.3.0"
+                "php": ">=5.3.0",
+                "psr/container": "^1.0"
+            },
+            "require-dev": {
+                "symfony/phpunit-bridge": "^3.2"
            },
            "type": "library",
            "extra": {
                "branch-alias": {
-                    "dev-master": "3.0.x-dev"
+                    "dev-master": "3.2.x-dev"
                }
            },
            "autoload": {
@@ -121,20 +131,69 @@
                "container",
                "dependency injection"
            ],
-            "time": "2015-09-11 15:10:35"
+            "time": "2018-01-21T07:42:36+00:00"
        },
        {
-            "name": "psr/http-message",
-            "version": "1.0",
+            "name": "psr/container",
+            "version": "1.0.0",
            "source": {
                "type": "git",
-                "url": "https://github.com/php-fig/http-message.git",
-                "reference": "85d63699f0dbedb190bbd4b0d2b9dc707ea4c298"
+                "url": "https://github.com/php-fig/container.git",
+                "reference": "b7ce3b176482dbbc1245ebf52b181af44c2cf55f"
            },
            "dist": {
                "type": "zip",
-                "url": "https://api.github.com/repos/php-fig/http-message/zipball/85d63699f0dbedb190bbd4b0d2b9dc707ea4c298",
-                "reference": "85d63699f0dbedb190bbd4b0d2b9dc707ea4c298",
+                "url": "https://api.github.com/repos/php-fig/container/zipball/b7ce3b176482dbbc1245ebf52b181af44c2cf55f",
+                "reference": "b7ce3b176482dbbc1245ebf52b181af44c2cf55f",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.0.x-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Psr\\Container\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "PHP-FIG",
+                    "homepage": "http://www.php-fig.org/"
+                }
+            ],
+            "description": "Common Container Interface (PHP FIG PSR-11)",
+            "homepage": "https://github.com/php-fig/container",
+            "keywords": [
+                "PSR-11",
+                "container",
+                "container-interface",
+                "container-interop",
+                "psr"
+            ],
+            "time": "2017-02-14T16:28:37+00:00"
+        },
+        {
+            "name": "psr/http-message",
+            "version": "1.0.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/php-fig/http-message.git",
+                "reference": "f6561bf28d520154e4b0ec72be95418abe6d9363"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/php-fig/http-message/zipball/f6561bf28d520154e4b0ec72be95418abe6d9363",
+                "reference": "f6561bf28d520154e4b0ec72be95418abe6d9363",
                "shasum": ""
            },
            "require": {
@@ -162,6 +221,7 @@
                }
            ],
            "description": "Common interface for HTTP messages",
+            "homepage": "https://github.com/php-fig/http-message",
            "keywords": [
                "http",
                "http-message",
@@ -170,31 +230,36 @@
                "request",
                "response"
            ],
-            "time": "2015-05-04 20:22:00"
+            "time": "2016-08-06T14:39:51+00:00"
        },
        {
            "name": "slim/slim",
-            "version": "3.0.0",
+            "version": "3.11.0",
            "source": {
                "type": "git",
                "url": "https://github.com/slimphp/Slim.git",
-                "reference": "3b06f0f2d84dabbe81b6cea46ace46a3e883253e"
+                "reference": "d378e70431e78ee92ee32ddde61ecc72edf5dc0a"
            },
            "dist": {
                "type": "zip",
-                "url": "https://api.github.com/repos/slimphp/Slim/zipball/3b06f0f2d84dabbe81b6cea46ace46a3e883253e",
-                "reference": "3b06f0f2d84dabbe81b6cea46ace46a3e883253e",
+                "url": "https://api.github.com/repos/slimphp/Slim/zipball/d378e70431e78ee92ee32ddde61ecc72edf5dc0a",
+                "reference": "d378e70431e78ee92ee32ddde61ecc72edf5dc0a",
                "shasum": ""
            },
            "require": {
-                "container-interop/container-interop": "^1.1",
-                "nikic/fast-route": "^0.6",
+                "container-interop/container-interop": "^1.2",
+                "nikic/fast-route": "^1.0",
                "php": ">=5.5.0",
                "pimple/pimple": "^3.0",
+                "psr/container": "^1.0",
                "psr/http-message": "^1.0"
            },
+            "provide": {
+                "psr/http-message-implementation": "1.0"
+            },
            "require-dev": {
-                "phpunit/phpunit": "^4.0"
+                "phpunit/phpunit": "^4.0",
+                "squizlabs/php_codesniffer": "^2.5"
            },
            "type": "library",
            "autoload": {
@@ -229,29 +294,92 @@
                }
            ],
            "description": "Slim is a PHP micro framework that helps you quickly write simple yet powerful web applications and APIs",
-            "homepage": "http://slimframework.com",
+            "homepage": "https://slimframework.com",
            "keywords": [
                "api",
                "framework",
                "micro",
                "router"
            ],
-            "time": "2015-12-07 14:11:09"
+            "time": "2018-09-16T10:54:21+00:00"
        }
    ],
    "packages-dev": [
        {
-            "name": "lcobucci/jwt",
-            "version": "3.1.1",
+            "name": "defuse/php-encryption",
+            "version": "v2.2.1",
            "source": {
                "type": "git",
-                "url": "https://github.com/lcobucci/jwt.git",
-                "reference": "afea8e682e911a21574fd8519321b32522fa25b5"
+                "url": "https://github.com/defuse/php-encryption.git",
+                "reference": "0f407c43b953d571421e0020ba92082ed5fb7620"
            },
            "dist": {
                "type": "zip",
-                "url": "https://api.github.com/repos/lcobucci/jwt/zipball/afea8e682e911a21574fd8519321b32522fa25b5",
-                "reference": "afea8e682e911a21574fd8519321b32522fa25b5",
+                "url": "https://api.github.com/repos/defuse/php-encryption/zipball/0f407c43b953d571421e0020ba92082ed5fb7620",
+                "reference": "0f407c43b953d571421e0020ba92082ed5fb7620",
+                "shasum": ""
+            },
+            "require": {
+                "ext-openssl": "*",
+                "paragonie/random_compat": ">= 2",
+                "php": ">=5.4.0"
+            },
+            "require-dev": {
+                "nikic/php-parser": "^2.0|^3.0|^4.0",
+                "phpunit/phpunit": "^4|^5"
+            },
+            "bin": [
+                "bin/generate-defuse-key"
+            ],
+            "type": "library",
+            "autoload": {
+                "psr-4": {
+                    "Defuse\\Crypto\\": "src"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Taylor Hornby",
+                    "email": "taylor@defuse.ca",
+                    "homepage": "https://defuse.ca/"
+                },
+                {
+                    "name": "Scott Arciszewski",
+                    "email": "info@paragonie.com",
+                    "homepage": "https://paragonie.com"
+                }
+            ],
+            "description": "Secure PHP Encryption Library",
+            "keywords": [
+                "aes",
+                "authenticated encryption",
+                "cipher",
+                "crypto",
+                "cryptography",
+                "encrypt",
+                "encryption",
+                "openssl",
+                "security",
+                "symmetric key cryptography"
+            ],
+            "time": "2018-07-24T23:27:56+00:00"
+        },
+        {
+            "name": "lcobucci/jwt",
+            "version": "3.2.4",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/lcobucci/jwt.git",
+                "reference": "c9704b751315d21735dc98d78d4f37bd73596da7"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/lcobucci/jwt/zipball/c9704b751315d21735dc98d78d4f37bd73596da7",
+                "reference": "c9704b751315d21735dc98d78d4f37bd73596da7",
                "shasum": ""
            },
            "require": {
@@ -259,7 +387,7 @@
                "php": ">=5.5"
            },
            "require-dev": {
-                "mdanter/ecc": "~0.3",
+                "mdanter/ecc": "~0.3.1",
                "mikey179/vfsstream": "~1.5",
                "phpmd/phpmd": "~2.2",
                "phpunit/php-invoker": "~1.1",
@@ -296,7 +424,7 @@
                "JWS",
                "jwt"
            ],
-            "time": "2016-03-24 22:46:13"
+            "time": "2018-08-03T11:23:50+00:00"
        },
        {
            "name": "league/event",
@@ -346,37 +474,33 @@
                "event",
                "listener"
            ],
-            "time": "2015-05-21 12:24:47"
+            "time": "2015-05-21T12:24:47+00:00"
        },
        {
            "name": "paragonie/random_compat",
-            "version": "v1.4.1",
+            "version": "v9.99.99",
            "source": {
                "type": "git",
                "url": "https://github.com/paragonie/random_compat.git",
-                "reference": "c7e26a21ba357863de030f0b9e701c7d04593774"
+                "reference": "84b4dfb120c6f9b4ff7b3685f9b8f1aa365a0c95"
            },
            "dist": {
                "type": "zip",
-                "url": "https://api.github.com/repos/paragonie/random_compat/zipball/c7e26a21ba357863de030f0b9e701c7d04593774",
-                "reference": "c7e26a21ba357863de030f0b9e701c7d04593774",
+                "url": "https://api.github.com/repos/paragonie/random_compat/zipball/84b4dfb120c6f9b4ff7b3685f9b8f1aa365a0c95",
+                "reference": "84b4dfb120c6f9b4ff7b3685f9b8f1aa365a0c95",
                "shasum": ""
            },
            "require": {
-                "php": ">=5.2.0"
+                "php": "^7"
            },
            "require-dev": {
-                "phpunit/phpunit": "4.*|5.*"
+                "phpunit/phpunit": "4.*|5.*",
+                "vimeo/psalm": "^1"
            },
            "suggest": {
                "ext-libsodium": "Provides a modern crypto API that can be used to generate random bytes."
            },
            "type": "library",
-            "autoload": {
-                "files": [
-                    "lib/random.php"
-                ]
-            },
            "notification-url": "https://packagist.org/downloads/",
            "license": [
                "MIT"
@@ -391,10 +515,129 @@
            "description": "PHP 5.x polyfill for random_bytes() and random_int() from PHP 7",
            "keywords": [
                "csprng",
+                "polyfill",
                "pseudorandom",
                "random"
            ],
-            "time": "2016-03-18 20:34:03"
+            "time": "2018-07-02T15:55:56+00:00"
+        },
+        {
+            "name": "psr/http-factory",
+            "version": "1.0.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/php-fig/http-factory.git",
+                "reference": "378bfe27931ecc54ff824a20d6f6bfc303bbd04c"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/php-fig/http-factory/zipball/378bfe27931ecc54ff824a20d6f6bfc303bbd04c",
+                "reference": "378bfe27931ecc54ff824a20d6f6bfc303bbd04c",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=7.0.0",
+                "psr/http-message": "^1.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.0.x-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Psr\\Http\\Message\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "PHP-FIG",
+                    "homepage": "http://www.php-fig.org/"
+                }
+            ],
+            "description": "Common interfaces for PSR-7 HTTP message factories",
+            "keywords": [
+                "factory",
+                "http",
+                "message",
+                "psr",
+                "psr-17",
+                "psr-7",
+                "request",
+                "response"
+            ],
+            "time": "2018-07-30T21:54:04+00:00"
+        },
+        {
+            "name": "zendframework/zend-diactoros",
+            "version": "2.0.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/zendframework/zend-diactoros.git",
+                "reference": "0bae78192e634774b5584f0210c1232da82cb1ff"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/zendframework/zend-diactoros/zipball/0bae78192e634774b5584f0210c1232da82cb1ff",
+                "reference": "0bae78192e634774b5584f0210c1232da82cb1ff",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^7.1",
+                "psr/http-factory": "^1.0",
+                "psr/http-message": "^1.0"
+            },
+            "provide": {
+                "psr/http-factory-implementation": "1.0",
+                "psr/http-message-implementation": "1.0"
+            },
+            "require-dev": {
+                "ext-dom": "*",
+                "ext-libxml": "*",
+                "http-interop/http-factory-tests": "^0.5.0",
+                "php-http/psr7-integration-tests": "dev-master",
+                "phpunit/phpunit": "^7.0.2",
+                "zendframework/zend-coding-standard": "~1.0.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "2.0.x-dev",
+                    "dev-develop": "2.1.x-dev",
+                    "dev-release-1.8": "1.8.x-dev"
+                }
+            },
+            "autoload": {
+                "files": [
+                    "src/functions/create_uploaded_file.php",
+                    "src/functions/marshal_headers_from_sapi.php",
+                    "src/functions/marshal_method_from_sapi.php",
+                    "src/functions/marshal_protocol_version_from_sapi.php",
+                    "src/functions/marshal_uri_from_sapi.php",
+                    "src/functions/normalize_server.php",
+                    "src/functions/normalize_uploaded_files.php",
+                    "src/functions/parse_cookie_header.php"
+                ],
+                "psr-4": {
+                    "Zend\\Diactoros\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "description": "PSR HTTP Message implementations",
+            "keywords": [
+                "http",
+                "psr",
+                "psr-7"
+            ],
+            "time": "2018-09-27T19:49:04+00:00"
        }
    ],
    "aliases": [],
--- a/examples/public/api.php
+++ b/examples/public/api.php
@@ -31,7 +31,6 @@ $app->add(
 $app->get(
    '/users',
    function (ServerRequestInterface $request, ResponseInterface $response) use ($app) {
-
        $users = [
            [
                'id'    => 123,
@@ -50,16 +49,18 @@ $app->get(
            ],
        ];

+        $totalUsers = count($users);
+
        // If the access token doesn't have the `basic` scope hide users' names
        if (in_array('basic', $request->getAttribute('oauth_scopes')) === false) {
-            for ($i = 0; $i < count($users); $i++) {
+            for ($i = 0; $i < $totalUsers; $i++) {
                unset($users[$i]['name']);
            }
        }

        // If the access token doesn't have the `email` scope hide users' email addresses
        if (in_array('email', $request->getAttribute('oauth_scopes')) === false) {
-            for ($i = 0; $i < count($users); $i++) {
+            for ($i = 0; $i < $totalUsers; $i++) {
                unset($users[$i]['email']);
            }
        }
@@ -70,4 +71,4 @@ $app->get(
    }
 );

-$app->run();
+$app->run();
--- a/examples/public/auth_code.php
+++ b/examples/public/auth_code.php
@@ -36,7 +36,6 @@ $app = new App([
        $refreshTokenRepository = new RefreshTokenRepository();

        $privateKeyPath = 'file://' . __DIR__ . '/../private.key';
-        $publicKeyPath = 'file://' . __DIR__ . '/../public.key';

        // Setup the authorization server
        $server = new AuthorizationServer(
@@ -44,7 +43,7 @@ $app = new App([
            $accessTokenRepository,
            $scopeRepository,
            $privateKeyPath,
-            $publicKeyPath
+            'lxZFUEsBCJ2Yb14IF2ygAHI5N4+ZAUXXaSeeJm6+twsUmIen'
        );

        // Enable the authentication code grant on the server with a token TTL of 1 hour
--- a/examples/public/client_credentials.php
+++ b/examples/public/client_credentials.php
@@ -30,9 +30,8 @@ $app = new App([
        $accessTokenRepository = new AccessTokenRepository(); // instance of AccessTokenRepositoryInterface

        // Path to public and private keys
-        $privateKey = 'file://'.__DIR__.'/../private.key';
+        $privateKey = 'file://' . __DIR__ . '/../private.key';
        //$privateKey = new CryptKey('file://path/to/private.key', 'passphrase'); // if private key has a pass phrase
-        $publicKey = 'file://'.__DIR__.'/../public.key';

        // Setup the authorization server
        $server = new AuthorizationServer(
@@ -40,7 +39,7 @@ $app = new App([
            $accessTokenRepository,
            $scopeRepository,
            $privateKey,
-            $publicKey
+            'lxZFUEsBCJ2Yb14IF2ygAHI5N4+ZAUXXaSeeJm6+twsUmIen'
        );

        // Enable the client credentials grant on the server
--- a/examples/public/implicit.php
+++ b/examples/public/implicit.php
@@ -32,7 +32,6 @@ $app = new App([
        $accessTokenRepository = new AccessTokenRepository();

        $privateKeyPath = 'file://' . __DIR__ . '/../private.key';
-        $publicKeyPath = 'file://' . __DIR__ . '/../public.key';

        // Setup the authorization server
        $server = new AuthorizationServer(
@@ -40,7 +39,7 @@ $app = new App([
            $accessTokenRepository,
            $scopeRepository,
            $privateKeyPath,
-            $publicKeyPath
+            'lxZFUEsBCJ2Yb14IF2ygAHI5N4+ZAUXXaSeeJm6+twsUmIen'
        );

        // Enable the implicit grant on the server with a token TTL of 1 hour
--- a/examples/public/middleware_use.php
+++ b/examples/public/middleware_use.php
@@ -12,6 +12,7 @@ use League\OAuth2\Server\Grant\AuthCodeGrant;
 use League\OAuth2\Server\Grant\RefreshTokenGrant;
 use League\OAuth2\Server\Middleware\AuthorizationServerMiddleware;
 use League\OAuth2\Server\Middleware\ResourceServerMiddleware;
+use League\OAuth2\Server\ResourceServer;
 use OAuth2ServerExamples\Repositories\AccessTokenRepository;
 use OAuth2ServerExamples\Repositories\AuthCodeRepository;
 use OAuth2ServerExamples\Repositories\ClientRepository;
@@ -37,7 +38,6 @@ $app = new App([
        $refreshTokenRepository = new RefreshTokenRepository();

        $privateKeyPath = 'file://' . __DIR__ . '/../private.key';
-        $publicKeyPath = 'file://' . __DIR__ . '/../public.key';

        // Setup the authorization server
        $server = new AuthorizationServer(
@@ -45,7 +45,7 @@ $app = new App([
            $accessTokenRepository,
            $scopeRepository,
            $privateKeyPath,
-            $publicKeyPath
+            'lxZFUEsBCJ2Yb14IF2ygAHI5N4+ZAUXXaSeeJm6+twsUmIen'
        );

        // Enable the authentication code grant on the server with a token TTL of 1 hour
@@ -61,7 +61,17 @@ $app = new App([
        // Enable the refresh token grant on the server with a token TTL of 1 month
        $server->enableGrantType(
            new RefreshTokenGrant($refreshTokenRepository),
-            new \DateInterval('PT1M')
+            new \DateInterval('P1M')
+        );
+
+        return $server;
+    },
+    ResourceServer::class => function () {
+        $publicKeyPath = 'file://' . __DIR__ . '/../public.key';
+
+        $server = new ResourceServer(
+            new AccessTokenRepository(),
+            $publicKeyPath
        );

        return $server;
@@ -94,6 +104,6 @@ $app->group('/api', function () {

        return $response->withBody($body);
    });
-})->add(new ResourceServerMiddleware($app->getContainer()->get(AuthorizationServer::class)));
+})->add(new ResourceServerMiddleware($app->getContainer()->get(ResourceServer::class)));

 $app->run();
--- a/examples/public/password.php
+++ b/examples/public/password.php
@@ -23,8 +23,8 @@ $app = new App([
            new ClientRepository(),                 // instance of ClientRepositoryInterface
            new AccessTokenRepository(),            // instance of AccessTokenRepositoryInterface
            new ScopeRepository(),                  // instance of ScopeRepositoryInterface
-            'file://'.__DIR__.'/../private.key',    // path to private key
-            'file://'.__DIR__.'/../public.key'      // path to public key
+            'file://' . __DIR__ . '/../private.key',    // path to private key
+            'lxZFUEsBCJ2Yb14IF2ygAHI5N4+ZAUXXaSeeJm6+twsUmIen'      // encryption key
        );

        $grant = new PasswordGrant(
@@ -54,19 +54,17 @@ $app->post(

            // Try to respond to the access token request
            return $server->respondToAccessTokenRequest($request, $response);
-
        } catch (OAuthServerException $exception) {

            // All instances of OAuthServerException can be converted to a PSR-7 response
            return $exception->generateHttpResponse($response);
-
        } catch (\Exception $exception) {

            // Catch unexpected exceptions
            $body = $response->getBody();
            $body->write($exception->getMessage());
-            return $response->withStatus(500)->withBody($body);

+            return $response->withStatus(500)->withBody($body);
        }
    }
 );
--- a/examples/public/refresh_token.php
+++ b/examples/public/refresh_token.php
@@ -17,7 +17,6 @@ use OAuth2ServerExamples\Repositories\ScopeRepository;
 use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\ServerRequestInterface;
 use Slim\App;
-use Zend\Diactoros\Stream;

 include __DIR__ . '/../vendor/autoload.php';

@@ -33,7 +32,6 @@ $app = new App([
        $refreshTokenRepository = new RefreshTokenRepository();

        $privateKeyPath = 'file://' . __DIR__ . '/../private.key';
-        $publicKeyPath = 'file://' . __DIR__ . '/../public.key';

        // Setup the authorization server
        $server = new AuthorizationServer(
@@ -41,7 +39,7 @@ $app = new App([
            $accessTokenRepository,
            $scopeRepository,
            $privateKeyPath,
-            $publicKeyPath
+            'lxZFUEsBCJ2Yb14IF2ygAHI5N4+ZAUXXaSeeJm6+twsUmIen'
        );

        // Enable the refresh token grant on the server
@@ -66,10 +64,9 @@ $app->post('/access_token', function (ServerRequestInterface $request, ResponseI
    } catch (OAuthServerException $exception) {
        return $exception->generateHttpResponse($response);
    } catch (\Exception $exception) {
-        $body = new Stream('php://temp', 'r+');
-        $body->write($exception->getMessage());
+        $response->getBody()->write($exception->getMessage());

-        return $response->withStatus(500)->withBody($body);
+        return $response->withStatus(500);
    }
 });

--- a/examples/src/Entities/ScopeEntity.php
+++ b/examples/src/Entities/ScopeEntity.php
@@ -11,13 +11,9 @@ namespace OAuth2ServerExamples\Entities;

 use League\OAuth2\Server\Entities\ScopeEntityInterface;
 use League\OAuth2\Server\Entities\Traits\EntityTrait;
+use League\OAuth2\Server\Entities\Traits\ScopeTrait;

 class ScopeEntity implements ScopeEntityInterface
 {
-    use EntityTrait;
-
-    public function jsonSerialize()
-    {
-        return $this->getIdentifier();
-    }
+    use EntityTrait, ScopeTrait;
 }
--- a/examples/src/Repositories/ClientRepository.php
+++ b/examples/src/Repositories/ClientRepository.php
@@ -17,7 +17,7 @@ class ClientRepository implements ClientRepositoryInterface
    /**
     * {@inheritdoc}
     */
-    public function getClientEntity($clientIdentifier, $grantType, $clientSecret = null, $mustValidateSecret = true)
+    public function getClientEntity($clientIdentifier, $grantType = null, $clientSecret = null, $mustValidateSecret = true)
    {
        $clients = [
            'myawesomeapp' => [
--- a/examples/src/Repositories/RefreshTokenRepository.php
+++ b/examples/src/Repositories/RefreshTokenRepository.php
@@ -18,7 +18,7 @@ class RefreshTokenRepository implements RefreshTokenRepositoryInterface
    /**
     * {@inheritdoc}
     */
-    public function persistNewRefreshToken(RefreshTokenEntityInterface $refreshTokenEntityInterface)
+    public function persistNewRefreshToken(RefreshTokenEntityInterface $refreshTokenEntity)
    {
        // Some logic to persist the refresh token in a database
    }
--- a/examples/src/Repositories/ScopeRepository.php
+++ b/examples/src/Repositories/ScopeRepository.php
@@ -54,7 +54,7 @@ class ScopeRepository implements ScopeRepositoryInterface
            $scope->setIdentifier('email');
            $scopes[] = $scope;
        }
-        
+
        return $scopes;
    }
 }
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -0,0 +1,10 @@
+includes:
+	- vendor/phpstan/phpstan-phpunit/extension.neon
+	- vendor/phpstan/phpstan-phpunit/rules.neon
+	- vendor/phpstan/phpstan-phpunit/strictRules.neon
+	- vendor/phpstan/phpstan-strict-rules/rules.neon
+services:
+	-
+		class: LeagueTests\PHPStan\AbstractGrantExtension
+		tags:
+			- phpstan.broker.dynamicMethodReturnTypeExtension
--- a/src/AuthorizationServer.php
+++ b/src/AuthorizationServer.php
@@ -10,6 +10,7 @@
 namespace League\OAuth2\Server;

 use DateInterval;
+use Defuse\Crypto\Key;
 use League\Event\EmitterAwareInterface;
 use League\Event\EmitterAwareTrait;
 use League\OAuth2\Server\Exception\OAuthServerException;
@@ -18,6 +19,7 @@ use League\OAuth2\Server\Repositories\AccessTokenRepositoryInterface;
 use League\OAuth2\Server\Repositories\ClientRepositoryInterface;
 use League\OAuth2\Server\Repositories\ScopeRepositoryInterface;
 use League\OAuth2\Server\RequestTypes\AuthorizationRequest;
+use League\OAuth2\Server\ResponseTypes\AbstractResponseType;
 use League\OAuth2\Server\ResponseTypes\BearerTokenResponse;
 use League\OAuth2\Server\ResponseTypes\ResponseTypeInterface;
 use Psr\Http\Message\ResponseInterface;
@@ -28,22 +30,22 @@ class AuthorizationServer implements EmitterAwareInterface
    use EmitterAwareTrait;

    /**
-     * @var \League\OAuth2\Server\Grant\GrantTypeInterface[]
+     * @var GrantTypeInterface[]
     */
    protected $enabledGrantTypes = [];

    /**
-     * @var \DateInterval[]
+     * @var DateInterval[]
     */
    protected $grantTypeAccessTokenTTL = [];

    /**
-     * @var \League\OAuth2\Server\CryptKey
+     * @var CryptKey
     */
    protected $privateKey;

    /**
-     * @var \League\OAuth2\Server\CryptKey
+     * @var CryptKey
     */
    protected $publicKey;

@@ -53,51 +55,64 @@ class AuthorizationServer implements EmitterAwareInterface
    protected $responseType;

    /**
-     * @var \League\OAuth2\Server\Repositories\ClientRepositoryInterface
+     * @var ClientRepositoryInterface
     */
    private $clientRepository;

    /**
-     * @var \League\OAuth2\Server\Repositories\AccessTokenRepositoryInterface
+     * @var AccessTokenRepositoryInterface
     */
    private $accessTokenRepository;

    /**
-     * @var \League\OAuth2\Server\Repositories\ScopeRepositoryInterface
+     * @var ScopeRepositoryInterface
     */
    private $scopeRepository;

+    /**
+     * @var string|Key
+     */
+    private $encryptionKey;
+
+    /**
+     * @var string
+     */
+    private $defaultScope = '';
+
    /**
     * New server instance.
     *
-     * @param \League\OAuth2\Server\Repositories\ClientRepositoryInterface      $clientRepository
-     * @param \League\OAuth2\Server\Repositories\AccessTokenRepositoryInterface $accessTokenRepository
-     * @param \League\OAuth2\Server\Repositories\ScopeRepositoryInterface       $scopeRepository
-     * @param \League\OAuth2\Server\CryptKey|string                             $privateKey
-     * @param \League\OAuth2\Server\CryptKey|string                             $publicKey
-     * @param null|\League\OAuth2\Server\ResponseTypes\ResponseTypeInterface    $responseType
+     * @param ClientRepositoryInterface      $clientRepository
+     * @param AccessTokenRepositoryInterface $accessTokenRepository
+     * @param ScopeRepositoryInterface       $scopeRepository
+     * @param CryptKey|string                $privateKey
+     * @param string|Key                     $encryptionKey
+     * @param null|ResponseTypeInterface     $responseType
     */
    public function __construct(
        ClientRepositoryInterface $clientRepository,
        AccessTokenRepositoryInterface $accessTokenRepository,
        ScopeRepositoryInterface $scopeRepository,
        $privateKey,
-        $publicKey,
+        $encryptionKey,
        ResponseTypeInterface $responseType = null
    ) {
        $this->clientRepository = $clientRepository;
        $this->accessTokenRepository = $accessTokenRepository;
        $this->scopeRepository = $scopeRepository;

-        if (!$privateKey instanceof CryptKey) {
+        if ($privateKey instanceof CryptKey === false) {
            $privateKey = new CryptKey($privateKey);
        }
-        $this->privateKey = $privateKey;

-        if (!$publicKey instanceof CryptKey) {
-            $publicKey = new CryptKey($publicKey);
+        $this->privateKey = $privateKey;
+        $this->encryptionKey = $encryptionKey;
+
+        if ($responseType === null) {
+            $responseType = new BearerTokenResponse();
+        } else {
+            $responseType = clone $responseType;
        }
-        $this->publicKey = $publicKey;

        $this->responseType = $responseType;
    }
@@ -105,21 +120,22 @@ class AuthorizationServer implements EmitterAwareInterface
    /**
     * Enable a grant type on the server.
     *
-     * @param \League\OAuth2\Server\Grant\GrantTypeInterface $grantType
-     * @param \DateInterval                                  $accessTokenTTL
+     * @param GrantTypeInterface $grantType
+     * @param null|DateInterval  $accessTokenTTL
     */
    public function enableGrantType(GrantTypeInterface $grantType, DateInterval $accessTokenTTL = null)
    {
        if ($accessTokenTTL instanceof DateInterval === false) {
-            $accessTokenTTL = new \DateInterval('PT1H');
+            $accessTokenTTL = new DateInterval('PT1H');
        }

        $grantType->setAccessTokenRepository($this->accessTokenRepository);
        $grantType->setClientRepository($this->clientRepository);
        $grantType->setScopeRepository($this->scopeRepository);
+        $grantType->setDefaultScope($this->defaultScope);
        $grantType->setPrivateKey($this->privateKey);
-        $grantType->setPublicKey($this->publicKey);
        $grantType->setEmitter($this->getEmitter());
+        $grantType->setEncryptionKey($this->encryptionKey);

        $this->enabledGrantTypes[$grantType->getIdentifier()] = $grantType;
        $this->grantTypeAccessTokenTTL[$grantType->getIdentifier()] = $accessTokenTTL;
@@ -128,22 +144,17 @@ class AuthorizationServer implements EmitterAwareInterface
    /**
     * Validate an authorization request
     *
-     * @param \Psr\Http\Message\ServerRequestInterface $request
+     * @param ServerRequestInterface $request
     *
-     * @throws \League\OAuth2\Server\Exception\OAuthServerException
+     * @throws OAuthServerException
     *
-     * @return \League\OAuth2\Server\RequestTypes\AuthorizationRequest|null
+     * @return AuthorizationRequest
     */
    public function validateAuthorizationRequest(ServerRequestInterface $request)
    {
-        $authRequest = null;
-        $enabledGrantTypes = $this->enabledGrantTypes;
-        while ($authRequest === null && $grantType = array_shift($enabledGrantTypes)) {
-            /** @var \League\OAuth2\Server\Grant\GrantTypeInterface $grantType */
+        foreach ($this->enabledGrantTypes as $grantType) {
            if ($grantType->canRespondToAuthorizationRequest($request)) {
-                $authRequest = $grantType->validateAuthorizationRequest($request);
-
-                return $authRequest;
+                return $grantType->validateAuthorizationRequest($request);
            }
        }

@@ -153,10 +164,10 @@ class AuthorizationServer implements EmitterAwareInterface
    /**
     * Complete an authorization request
     *
-     * @param \League\OAuth2\Server\RequestTypes\AuthorizationRequest $authRequest
-     * @param \Psr\Http\Message\ResponseInterface                     $response
+     * @param AuthorizationRequest $authRequest
+     * @param ResponseInterface    $response
     *
-     * @return \Psr\Http\Message\ResponseInterface
+     * @return ResponseInterface
     */
    public function completeAuthorizationRequest(AuthorizationRequest $authRequest, ResponseInterface $response)
    {
@@ -168,29 +179,28 @@ class AuthorizationServer implements EmitterAwareInterface
    /**
     * Return an access token response.
     *
-     * @param \Psr\Http\Message\ServerRequestInterface $request
-     * @param \Psr\Http\Message\ResponseInterface      $response
+     * @param ServerRequestInterface $request
+     * @param ResponseInterface      $response
     *
-     * @throws \League\OAuth2\Server\Exception\OAuthServerException
+     * @throws OAuthServerException
     *
-     * @return \Psr\Http\Message\ResponseInterface
+     * @return ResponseInterface
     */
    public function respondToAccessTokenRequest(ServerRequestInterface $request, ResponseInterface $response)
    {
-        $tokenResponse = null;
-        while ($tokenResponse === null && $grantType = array_shift($this->enabledGrantTypes)) {
-            /** @var \League\OAuth2\Server\Grant\GrantTypeInterface $grantType */
-            if ($grantType->canRespondToAccessTokenRequest($request)) {
-                $tokenResponse = $grantType->respondToAccessTokenRequest(
-                    $request,
-                    $this->getResponseType(),
-                    $this->grantTypeAccessTokenTTL[$grantType->getIdentifier()]
-                );
+        foreach ($this->enabledGrantTypes as $grantType) {
+            if (!$grantType->canRespondToAccessTokenRequest($request)) {
+                continue;
            }
-        }
+            $tokenResponse = $grantType->respondToAccessTokenRequest(
+                $request,
+                $this->getResponseType(),
+                $this->grantTypeAccessTokenTTL[$grantType->getIdentifier()]
+            );

-        if ($tokenResponse instanceof ResponseTypeInterface) {
-            return $tokenResponse->generateHttpResponse($response);
+            if ($tokenResponse instanceof ResponseTypeInterface) {
+                return $tokenResponse->generateHttpResponse($response);
+            }
        }

        throw OAuthServerException::unsupportedGrantType();
@@ -203,12 +213,24 @@ class AuthorizationServer implements EmitterAwareInterface
     */
    protected function getResponseType()
    {
-        if (!$this->responseType instanceof ResponseTypeInterface) {
-            $this->responseType = new BearerTokenResponse();
+        $responseType = clone $this->responseType;
+
+        if ($responseType instanceof AbstractResponseType) {
+            $responseType->setPrivateKey($this->privateKey);
        }

-        $this->responseType->setPrivateKey($this->privateKey);
+        $responseType->setEncryptionKey($this->encryptionKey);

-        return $this->responseType;
+        return $responseType;
+    }
+
+    /**
+     * Set the default scope for the authorization server.
+     *
+     * @param string $defaultScope
+     */
+    public function setDefaultScope($defaultScope)
+    {
+        $this->defaultScope = $defaultScope;
    }
 }
--- a/src/AuthorizationValidators/BearerTokenValidator.php
+++ b/src/AuthorizationValidators/BearerTokenValidator.php
@@ -9,33 +9,50 @@

 namespace League\OAuth2\Server\AuthorizationValidators;

+use BadMethodCallException;
+use InvalidArgumentException;
 use Lcobucci\JWT\Parser;
 use Lcobucci\JWT\Signer\Rsa\Sha256;
 use Lcobucci\JWT\ValidationData;
+use League\OAuth2\Server\CryptKey;
 use League\OAuth2\Server\CryptTrait;
 use League\OAuth2\Server\Exception\OAuthServerException;
 use League\OAuth2\Server\Repositories\AccessTokenRepositoryInterface;
 use Psr\Http\Message\ServerRequestInterface;
+use RuntimeException;

 class BearerTokenValidator implements AuthorizationValidatorInterface
 {
    use CryptTrait;

    /**
-     * @var \League\OAuth2\Server\Repositories\AccessTokenRepositoryInterface
+     * @var AccessTokenRepositoryInterface
     */
    private $accessTokenRepository;

    /**
-     * BearerTokenValidator constructor.
-     *
-     * @param \League\OAuth2\Server\Repositories\AccessTokenRepositoryInterface $accessTokenRepository
+     * @var CryptKey
+     */
+    protected $publicKey;
+
+    /**
+     * @param AccessTokenRepositoryInterface $accessTokenRepository
     */
    public function __construct(AccessTokenRepositoryInterface $accessTokenRepository)
    {
        $this->accessTokenRepository = $accessTokenRepository;
    }

+    /**
+     * Set the public key
+     *
+     * @param CryptKey $key
+     */
+    public function setPublicKey(CryptKey $key)
+    {
+        $this->publicKey = $key;
+    }
+
    /**
     * {@inheritdoc}
     */
@@ -51,8 +68,12 @@ class BearerTokenValidator implements AuthorizationValidatorInterface
        try {
            // Attempt to parse and validate the JWT
            $token = (new Parser())->parse($jwt);
-            if ($token->verify(new Sha256(), $this->publicKey->getKeyPath()) === false) {
-                throw OAuthServerException::accessDenied('Access token could not be verified');
+            try {
+                if ($token->verify(new Sha256(), $this->publicKey->getKeyPath()) === false) {
+                    throw OAuthServerException::accessDenied('Access token could not be verified');
+                }
+            } catch (BadMethodCallException $exception) {
+                throw OAuthServerException::accessDenied('Access token is not signed', null, $exception);
            }

            // Ensure access token hasn't expired
@@ -74,12 +95,12 @@ class BearerTokenValidator implements AuthorizationValidatorInterface
                ->withAttribute('oauth_client_id', $token->getClaim('aud'))
                ->withAttribute('oauth_user_id', $token->getClaim('sub'))
                ->withAttribute('oauth_scopes', $token->getClaim('scopes'));
-        } catch (\InvalidArgumentException $exception) {
+        } catch (InvalidArgumentException $exception) {
            // JWT couldn't be parsed so return the request as is
-            throw OAuthServerException::accessDenied($exception->getMessage());
-        } catch(\RuntimeException $exception){
+            throw OAuthServerException::accessDenied($exception->getMessage(), null, $exception);
+        } catch (RuntimeException $exception) {
            //JWR couldn't be parsed so return the request as is
-            throw OAuthServerException::accessDenied('Error while decoding to JSON');
+            throw OAuthServerException::accessDenied('Error while decoding to JSON', null, $exception);
        }
    }
 }
--- a/src/CryptKey.php
+++ b/src/CryptKey.php
@@ -8,38 +8,99 @@
 *
 * @link        https://github.com/thephpleague/oauth2-server
 */
+
 namespace League\OAuth2\Server;

+use LogicException;
+use RuntimeException;
+
 class CryptKey
 {
+    const RSA_KEY_PATTERN =
+        '/^(-----BEGIN (RSA )?(PUBLIC|PRIVATE) KEY-----)\R.*(-----END (RSA )?(PUBLIC|PRIVATE) KEY-----)\R?$/s';
+
    /**
     * @var string
     */
    protected $keyPath;

    /**
-     * @var string
+     * @var null|string
     */
    protected $passPhrase;

    /**
     * @param string      $keyPath
     * @param null|string $passPhrase
+     * @param bool        $keyPermissionsCheck
     */
-    public function __construct($keyPath, $passPhrase = null)
+    public function __construct($keyPath, $passPhrase = null, $keyPermissionsCheck = true)
    {
+        if (preg_match(self::RSA_KEY_PATTERN, $keyPath)) {
+            $keyPath = $this->saveKeyToFile($keyPath);
+        }
+
        if (strpos($keyPath, 'file://') !== 0) {
            $keyPath = 'file://' . $keyPath;
        }

        if (!file_exists($keyPath) || !is_readable($keyPath)) {
-            throw new \LogicException(sprintf('Key path "%s" does not exist or is not readable', $keyPath));
+            throw new LogicException(sprintf('Key path "%s" does not exist or is not readable', $keyPath));
+        }
+
+        if ($keyPermissionsCheck === true) {
+            // Verify the permissions of the key
+            $keyPathPerms = decoct(fileperms($keyPath) & 0777);
+            if (in_array($keyPathPerms, ['400', '440', '600', '640', '660'], true) === false) {
+                trigger_error(sprintf(
+                    'Key file "%s" permissions are not correct, recommend changing to 600 or 660 instead of %s',
+                    $keyPath,
+                    $keyPathPerms
+                ), E_USER_NOTICE);
+            }
        }

        $this->keyPath = $keyPath;
        $this->passPhrase = $passPhrase;
    }

+    /**
+     * @param string $key
+     *
+     * @throws RuntimeException
+     *
+     * @return string
+     */
+    private function saveKeyToFile($key)
+    {
+        $tmpDir = sys_get_temp_dir();
+        $keyPath = $tmpDir . '/' . sha1($key) . '.key';
+
+        if (file_exists($keyPath)) {
+            return 'file://' . $keyPath;
+        }
+
+        if (!touch($keyPath)) {
+            // @codeCoverageIgnoreStart
+            throw new RuntimeException(sprintf('"%s" key file could not be created', $keyPath));
+            // @codeCoverageIgnoreEnd
+        }
+
+        if (file_put_contents($keyPath, $key) === false) {
+            // @codeCoverageIgnoreStart
+            throw new RuntimeException(sprintf('Unable to write key file to temporary directory "%s"', $tmpDir));
+            // @codeCoverageIgnoreEnd
+        }
+
+        if (chmod($keyPath, 0600) === false) {
+            // @codeCoverageIgnoreStart
+            throw new RuntimeException(sprintf('The key file "%s" file mode could not be changed with chmod to 600', $keyPath));
+            // @codeCoverageIgnoreEnd
+        }
+
+        return 'file://' . $keyPath;
+    }
+
    /**
     * Retrieve key path.
     *
--- a/src/CryptTrait.php
+++ b/src/CryptTrait.php
@@ -1,6 +1,6 @@
 <?php
 /**
- * Public/private key encryption.
+ * Encrypt/decrypt with encryptionKey.
 *
 * @author      Alex Bilbie <hello@alexbilbie.com>
 * @copyright   Copyright (c) Alex Bilbie
@@ -8,111 +8,72 @@
 *
 * @link        https://github.com/thephpleague/oauth2-server
 */
+
 namespace League\OAuth2\Server;

+use Defuse\Crypto\Crypto;
+use Defuse\Crypto\Key;
+use Exception;
+use LogicException;
+
 trait CryptTrait
 {
    /**
-     * @var \League\OAuth2\Server\CryptKey
+     * @var string|Key
     */
-    protected $privateKey;
+    protected $encryptionKey;

    /**
-     * @var \League\OAuth2\Server\CryptKey
-     */
-    protected $publicKey;
-
-    /**
-     * Set path to private key.
-     *
-     * @param \League\OAuth2\Server\CryptKey $privateKey
-     */
-    public function setPrivateKey(CryptKey $privateKey)
-    {
-        $this->privateKey = $privateKey;
-    }
-
-    /**
-     * Set path to public key.
-     *
-     * @param \League\OAuth2\Server\CryptKey $publicKey
-     */
-    public function setPublicKey(CryptKey $publicKey)
-    {
-        $this->publicKey = $publicKey;
-    }
-
-    /**
-     * Encrypt data with a private key.
+     * Encrypt data with encryptionKey.
     *
     * @param string $unencryptedData
     *
+     * @throws LogicException
+     *
     * @return string
     */
    protected function encrypt($unencryptedData)
    {
-        $privateKey = openssl_pkey_get_private($this->privateKey->getKeyPath(), $this->privateKey->getPassPhrase());
-        $privateKeyDetails = @openssl_pkey_get_details($privateKey);
-        if ($privateKeyDetails === null) {
-            throw new \LogicException(
-                sprintf('Could not get details of private key: %s', $this->privateKey->getKeyPath())
-            );
-        }
-
-        $chunkSize = ceil($privateKeyDetails['bits'] / 8) - 11;
-        $output = '';
-
-        while ($unencryptedData) {
-            $chunk = substr($unencryptedData, 0, $chunkSize);
-            $unencryptedData = substr($unencryptedData, $chunkSize);
-            if (openssl_private_encrypt($chunk, $encrypted, $privateKey) === false) {
-                // @codeCoverageIgnoreStart
-                throw new \LogicException('Failed to encrypt data');
-                // @codeCoverageIgnoreEnd
+        try {
+            if ($this->encryptionKey instanceof Key) {
+                return Crypto::encrypt($unencryptedData, $this->encryptionKey);
            }
-            $output .= $encrypted;
-        }
-        openssl_pkey_free($privateKey);

-        return base64_encode($output);
+            return Crypto::encryptWithPassword($unencryptedData, $this->encryptionKey);
+        } catch (Exception $e) {
+            throw new LogicException($e->getMessage(), null, $e);
+        }
    }

    /**
-     * Decrypt data with a public key.
+     * Decrypt data with encryptionKey.
     *
     * @param string $encryptedData
     *
-     * @throws \LogicException
+     * @throws LogicException
     *
     * @return string
     */
    protected function decrypt($encryptedData)
    {
-        $publicKey = openssl_pkey_get_public($this->publicKey->getKeyPath());
-        $publicKeyDetails = @openssl_pkey_get_details($publicKey);
-        if ($publicKeyDetails === null) {
-            throw new \LogicException(
-                sprintf('Could not get details of public key: %s', $this->publicKey->getKeyPath())
-            );
-        }
-
-        $chunkSize = ceil($publicKeyDetails['bits'] / 8);
-        $output = '';
-
-        $encryptedData = base64_decode($encryptedData);
-
-        while ($encryptedData) {
-            $chunk = substr($encryptedData, 0, $chunkSize);
-            $encryptedData = substr($encryptedData, $chunkSize);
-            if (openssl_public_decrypt($chunk, $decrypted, $publicKey/*, OPENSSL_PKCS1_OAEP_PADDING*/) === false) {
-                // @codeCoverageIgnoreStart
-                throw new \LogicException('Failed to decrypt data');
-                // @codeCoverageIgnoreEnd
+        try {
+            if ($this->encryptionKey instanceof Key) {
+                return Crypto::decrypt($encryptedData, $this->encryptionKey);
            }
-            $output .= $decrypted;
-        }
-        openssl_pkey_free($publicKey);

-        return $output;
+            return Crypto::decryptWithPassword($encryptedData, $this->encryptionKey);
+        } catch (Exception $e) {
+            throw new LogicException($e->getMessage(), null, $e);
+        }
+    }
+
+    /**
+     * Set the encryption key
+     *
+     * @param string|Key $key
+     */
+    public function setEncryptionKey($key = null)
+    {
+        $this->encryptionKey = $key;
    }
 }
--- a/src/Entities/AccessTokenEntityInterface.php
+++ b/src/Entities/AccessTokenEntityInterface.php
@@ -9,6 +9,7 @@

 namespace League\OAuth2\Server\Entities;

+use Lcobucci\JWT\Token;
 use League\OAuth2\Server\CryptKey;

 interface AccessTokenEntityInterface extends TokenInterface
@@ -16,9 +17,9 @@ interface AccessTokenEntityInterface extends TokenInterface
    /**
     * Generate a JWT from the access token
     *
-     * @param \League\OAuth2\Server\CryptKey $privateKey
+     * @param CryptKey $privateKey
     *
-     * @return string
+     * @return Token
     */
    public function convertToJWT(CryptKey $privateKey);
 }
--- a/src/Entities/AuthCodeEntityInterface.php
+++ b/src/Entities/AuthCodeEntityInterface.php
@@ -12,7 +12,7 @@ namespace League\OAuth2\Server\Entities;
 interface AuthCodeEntityInterface extends TokenInterface
 {
    /**
-     * @return string
+     * @return string|null
     */
    public function getRedirectUri();

--- a/src/Entities/RefreshTokenEntityInterface.php
+++ b/src/Entities/RefreshTokenEntityInterface.php
@@ -9,6 +9,8 @@

 namespace League\OAuth2\Server\Entities;

+use DateTime;
+
 interface RefreshTokenEntityInterface
 {
    /**
@@ -21,35 +23,35 @@ interface RefreshTokenEntityInterface
    /**
     * Set the token's identifier.
     *
-     * @param $identifier
+     * @param mixed $identifier
     */
    public function setIdentifier($identifier);

    /**
     * Get the token's expiry date time.
     *
-     * @return \DateTime
+     * @return DateTime
     */
    public function getExpiryDateTime();

    /**
     * Set the date time when the token expires.
     *
-     * @param \DateTime $dateTime
+     * @param DateTime $dateTime
     */
-    public function setExpiryDateTime(\DateTime $dateTime);
+    public function setExpiryDateTime(DateTime $dateTime);

    /**
     * Set the access token that the refresh token was associated with.
     *
-     * @param \League\OAuth2\Server\Entities\AccessTokenEntityInterface $accessToken
+     * @param AccessTokenEntityInterface $accessToken
     */
    public function setAccessToken(AccessTokenEntityInterface $accessToken);

    /**
     * Get the access token that the refresh token was originally associated with.
     *
-     * @return \League\OAuth2\Server\Entities\AccessTokenEntityInterface
+     * @return AccessTokenEntityInterface
     */
    public function getAccessToken();
 }
--- a/src/Entities/ScopeEntityInterface.php
+++ b/src/Entities/ScopeEntityInterface.php
@@ -9,7 +9,9 @@

 namespace League\OAuth2\Server\Entities;

-interface ScopeEntityInterface extends \JsonSerializable
+use JsonSerializable;
+
+interface ScopeEntityInterface extends JsonSerializable
 {
    /**
     * Get the scope's identifier.
--- a/src/Entities/TokenInterface.php
+++ b/src/Entities/TokenInterface.php
@@ -9,6 +9,8 @@

 namespace League\OAuth2\Server\Entities;

+use DateTime;
+
 interface TokenInterface
 {
    /**
@@ -21,35 +23,35 @@ interface TokenInterface
    /**
     * Set the token's identifier.
     *
-     * @param $identifier
+     * @param mixed $identifier
     */
    public function setIdentifier($identifier);

    /**
     * Get the token's expiry date time.
     *
-     * @return \DateTime
+     * @return DateTime
     */
    public function getExpiryDateTime();

    /**
     * Set the date time when the token expires.
     *
-     * @param \DateTime $dateTime
+     * @param DateTime $dateTime
     */
-    public function setExpiryDateTime(\DateTime $dateTime);
+    public function setExpiryDateTime(DateTime $dateTime);

    /**
     * Set the identifier of the user associated with the token.
     *
-     * @param string|int $identifier The identifier of the user
+     * @param string|int|null $identifier The identifier of the user
     */
    public function setUserIdentifier($identifier);

    /**
     * Get the token user's identifier.
     *
-     * @return string|int
+     * @return string|int|null
     */
    public function getUserIdentifier();

@@ -63,14 +65,14 @@ interface TokenInterface
    /**
     * Set the client that the token was issued to.
     *
-     * @param \League\OAuth2\Server\Entities\ClientEntityInterface $client
+     * @param ClientEntityInterface $client
     */
    public function setClient(ClientEntityInterface $client);

    /**
     * Associate a scope with the token.
     *
-     * @param \League\OAuth2\Server\Entities\ScopeEntityInterface $scope
+     * @param ScopeEntityInterface $scope
     */
    public function addScope(ScopeEntityInterface $scope);

--- a/src/Entities/Traits/AccessTokenTrait.php
+++ b/src/Entities/Traits/AccessTokenTrait.php
@@ -9,9 +9,11 @@

 namespace League\OAuth2\Server\Entities\Traits;

+use DateTime;
 use Lcobucci\JWT\Builder;
 use Lcobucci\JWT\Signer\Key;
 use Lcobucci\JWT\Signer\Rsa\Sha256;
+use Lcobucci\JWT\Token;
 use League\OAuth2\Server\CryptKey;
 use League\OAuth2\Server\Entities\ClientEntityInterface;
 use League\OAuth2\Server\Entities\ScopeEntityInterface;
@@ -21,9 +23,9 @@ trait AccessTokenTrait
    /**
     * Generate a JWT from the access token
     *
-     * @param \League\OAuth2\Server\CryptKey $privateKey
+     * @param CryptKey $privateKey
     *
-     * @return string
+     * @return Token
     */
    public function convertToJWT(CryptKey $privateKey)
    {
@@ -45,7 +47,7 @@ trait AccessTokenTrait
    abstract public function getClient();

    /**
-     * @return \DateTime
+     * @return DateTime
     */
    abstract public function getExpiryDateTime();

--- a/src/Entities/Traits/AuthCodeTrait.php
+++ b/src/Entities/Traits/AuthCodeTrait.php
@@ -17,7 +17,7 @@ trait AuthCodeTrait
    protected $redirectUri;

    /**
-     * @return string
+     * @return string|null
     */
    public function getRedirectUri()
    {
--- a/src/Entities/Traits/ClientTrait.php
+++ b/src/Entities/Traits/ClientTrait.php
@@ -11,8 +11,14 @@ namespace League\OAuth2\Server\Entities\Traits;

 trait ClientTrait
 {
+    /**
+     * @var string
+     */
    protected $name;

+    /**
+     * @var string|string[]
+     */
    protected $redirectUri;

    /**
--- a/src/Entities/Traits/EntityTrait.php
+++ b/src/Entities/Traits/EntityTrait.php
@@ -11,7 +11,7 @@ namespace League\OAuth2\Server\Entities\Traits;

 trait EntityTrait
 {
-    /*
+    /**
     * @var string
     */
    protected $identifier;
--- a/src/Entities/Traits/ScopeTrait.php
+++ b/src/Entities/Traits/ScopeTrait.php
@@ -0,0 +1,28 @@
+<?php
+/**
+ * @author    Andrew Millington <andrew@noexceptions.io>
+ * @copyright Copyright (c) Andrew Millington
+ * @license   http://mit-license.org
+ *
+ * @link      https://github.com/thephpleague/oauth2-server
+ */
+
+namespace League\OAuth2\Server\Entities\Traits;
+
+trait ScopeTrait
+{
+    /**
+     * Serialize the object to the scopes string identifier when using json_encode().
+     *
+     * @return string
+     */
+    public function jsonSerialize()
+    {
+        return $this->getIdentifier();
+    }
+
+    /**
+     * @return string
+     */
+    abstract public function getIdentifier();
+}
--- a/src/Entities/Traits/TokenEntityTrait.php
+++ b/src/Entities/Traits/TokenEntityTrait.php
@@ -26,7 +26,7 @@ trait TokenEntityTrait
    protected $expiryDateTime;

    /**
-     * @var string|int
+     * @var string|int|null
     */
    protected $userIdentifier;

@@ -38,7 +38,7 @@ trait TokenEntityTrait
    /**
     * Associate a scope with the token.
     *
-     * @param \League\OAuth2\Server\Entities\ScopeEntityInterface $scope
+     * @param ScopeEntityInterface $scope
     */
    public function addScope(ScopeEntityInterface $scope)
    {
@@ -78,7 +78,7 @@ trait TokenEntityTrait
    /**
     * Set the identifier of the user associated with the token.
     *
-     * @param string|int $identifier The identifier of the user
+     * @param string|int|null $identifier The identifier of the user
     */
    public function setUserIdentifier($identifier)
    {
@@ -88,7 +88,7 @@ trait TokenEntityTrait
    /**
     * Get the token user's identifier.
     *
-     * @return string|int
+     * @return string|int|null
     */
    public function getUserIdentifier()
    {
@@ -108,7 +108,7 @@ trait TokenEntityTrait
    /**
     * Set the client that the token was issued to.
     *
-     * @param \League\OAuth2\Server\Entities\ClientEntityInterface $client
+     * @param ClientEntityInterface $client
     */
    public function setClient(ClientEntityInterface $client)
    {
--- a/src/Exception/OAuthServerException.php
+++ b/src/Exception/OAuthServerException.php
@@ -9,9 +9,11 @@

 namespace League\OAuth2\Server\Exception;

+use Exception;
 use Psr\Http\Message\ResponseInterface;
+use Throwable;

-class OAuthServerException extends \Exception
+class OAuthServerException extends Exception
 {
    /**
     * @var int
@@ -33,6 +35,11 @@ class OAuthServerException extends \Exception
     */
    private $redirectUri;

+    /**
+     * @var array
+     */
+    private $payload;
+
    /**
     * Throw a new exception.
     *
@@ -42,14 +49,50 @@ class OAuthServerException extends \Exception
     * @param int         $httpStatusCode HTTP status code to send (default = 400)
     * @param null|string $hint           A helper hint
     * @param null|string $redirectUri    A HTTP URI to redirect the user back to
+     * @param Throwable   $previous       Previous exception
     */
-    public function __construct($message, $code, $errorType, $httpStatusCode = 400, $hint = null, $redirectUri = null)
+    public function __construct($message, $code, $errorType, $httpStatusCode = 400, $hint = null, $redirectUri = null, Throwable $previous = null)
    {
-        parent::__construct($message, $code);
+        parent::__construct($message, $code, $previous);
        $this->httpStatusCode = $httpStatusCode;
        $this->errorType = $errorType;
        $this->hint = $hint;
        $this->redirectUri = $redirectUri;
+        $this->payload = [
+            'error'             => $errorType,
+            'error_description' => $message,
+        ];
+        if ($hint !== null) {
+            $this->payload['hint'] = $hint;
+        }
+    }
+
+    /**
+     * Returns the current payload.
+     *
+     * @return array
+     */
+    public function getPayload()
+    {
+        $payload = $this->payload;
+
+        // The "message" property is deprecated and replaced by "error_description"
+        // TODO: remove "message" property
+        if (isset($payload['error_description']) && !isset($payload['message'])) {
+            $payload['message'] = $payload['error_description'];
+        }
+
+        return $payload;
+    }
+
+    /**
+     * Updates the current payload.
+     *
+     * @param array $payload
+     */
+    public function setPayload(array $payload)
+    {
+        $this->payload = $payload;
    }

    /**
@@ -60,7 +103,7 @@ class OAuthServerException extends \Exception
    public static function unsupportedGrantType()
    {
        $errorMessage = 'The authorization grant type is not supported by the authorization server.';
-        $hint = 'Check the `grant_type` parameter';
+        $hint = 'Check that all required parameters have been provided';

        return new static($errorMessage, 2, 'unsupported_grant_type', 400, $hint);
    }
@@ -69,17 +112,18 @@ class OAuthServerException extends \Exception
     * Invalid request error.
     *
     * @param string      $parameter The invalid parameter
-     * @param string|null $hint
+     * @param null|string $hint
+     * @param Throwable   $previous  Previous exception
     *
     * @return static
     */
-    public static function invalidRequest($parameter, $hint = null)
+    public static function invalidRequest($parameter, $hint = null, Throwable $previous = null)
    {
        $errorMessage = 'The request is missing a required parameter, includes an invalid parameter value, ' .
            'includes a parameter more than once, or is otherwise malformed.';
        $hint = ($hint === null) ? sprintf('Check the `%s` parameter', $parameter) : $hint;

-        return new static($errorMessage, 3, 'invalid_request', 400, $hint);
+        return new static($errorMessage, 3, 'invalid_request', 400, $hint, null, $previous);
    }

    /**
@@ -105,7 +149,15 @@ class OAuthServerException extends \Exception
    public static function invalidScope($scope, $redirectUri = null)
    {
        $errorMessage = 'The requested scope is invalid, unknown, or malformed';
-        $hint = sprintf('Check the `%s` scope', $scope);
+
+        if (empty($scope)) {
+            $hint = 'Specify a scope in the request or set a default scope';
+        } else {
+            $hint = sprintf(
+                'Check the `%s` scope',
+                htmlspecialchars($scope, ENT_QUOTES, 'UTF-8', false)
+            );
+        }

        return new static($errorMessage, 5, 'invalid_scope', 400, $hint, $redirectUri);
    }
@@ -123,44 +175,50 @@ class OAuthServerException extends \Exception
    /**
     * Server error.
     *
-     * @param $hint
+     * @param string    $hint
+     * @param Throwable $previous
     *
     * @return static
     *
     * @codeCoverageIgnore
     */
-    public static function serverError($hint)
+    public static function serverError($hint, Throwable $previous = null)
    {
        return new static(
            'The authorization server encountered an unexpected condition which prevented it from fulfilling'
            . ' the request: ' . $hint,
            7,
            'server_error',
-            500
+            500,
+            null,
+            null,
+            $previous
        );
    }

    /**
     * Invalid refresh token.
     *
-     * @param string|null $hint
+     * @param null|string $hint
+     * @param Throwable   $previous
     *
     * @return static
     */
-    public static function invalidRefreshToken($hint = null)
+    public static function invalidRefreshToken($hint = null, Throwable $previous = null)
    {
-        return new static('The refresh token is invalid.', 8, 'invalid_request', 400, $hint);
+        return new static('The refresh token is invalid.', 8, 'invalid_request', 401, $hint, null, $previous);
    }

    /**
     * Access denied.
     *
-     * @param string|null $hint
-     * @param string|null $redirectUri
+     * @param null|string $hint
+     * @param null|string $redirectUri
+     * @param Throwable   $previous
     *
     * @return static
     */
-    public static function accessDenied($hint = null, $redirectUri = null)
+    public static function accessDenied($hint = null, $redirectUri = null, Throwable $previous = null)
    {
        return new static(
            'The resource owner or authorization server denied the request.',
@@ -168,7 +226,8 @@ class OAuthServerException extends \Exception
            'access_denied',
            401,
            $hint,
-            $redirectUri
+            $redirectUri,
+            $previous
        );
    }

@@ -203,24 +262,17 @@ class OAuthServerException extends \Exception
    /**
     * Generate a HTTP response.
     *
-     * @param \Psr\Http\Message\ResponseInterface $response
-     * @param bool                                $useFragment True if errors should be in the URI fragment instead of
-     *                                                         query string
+     * @param ResponseInterface $response
+     * @param bool              $useFragment True if errors should be in the URI fragment instead of query string
+     * @param int               $jsonOptions options passed to json_encode
     *
-     * @return \Psr\Http\Message\ResponseInterface
+     * @return ResponseInterface
     */
-    public function generateHttpResponse(ResponseInterface $response, $useFragment = false)
+    public function generateHttpResponse(ResponseInterface $response, $useFragment = false, $jsonOptions = 0)
    {
        $headers = $this->getHttpHeaders();

-        $payload = [
-            'error'   => $this->getErrorType(),
-            'message' => $this->getMessage(),
-        ];
-
-        if ($this->hint !== null) {
-            $payload['hint'] = $this->hint;
-        }
+        $payload = $this->getPayload();

        if ($this->redirectUri !== null) {
            if ($useFragment === true) {
@@ -236,7 +288,7 @@ class OAuthServerException extends \Exception
            $response = $response->withHeader($header, $content);
        }

-        $response->getBody()->write(json_encode($payload));
+        $response->getBody()->write(json_encode($payload, $jsonOptions));

        return $response->withStatus($this->getHttpStatusCode());
    }
@@ -261,19 +313,30 @@ class OAuthServerException extends \Exception
        // include the "WWW-Authenticate" response header field
        // matching the authentication scheme used by the client.
        // @codeCoverageIgnoreStart
-        if ($this->errorType === 'invalid_client') {
-            $authScheme = 'Basic';
-            if (array_key_exists('HTTP_AUTHORIZATION', $_SERVER) !== false
-                && strpos($_SERVER['HTTP_AUTHORIZATION'], 'Bearer') === 0
-            ) {
-                $authScheme = 'Bearer';
-            }
-            $headers[] = 'WWW-Authenticate: ' . $authScheme . ' realm="OAuth"';
+        if ($this->errorType === 'invalid_client' && array_key_exists('HTTP_AUTHORIZATION', $_SERVER) !== false) {
+            $authScheme = strpos($_SERVER['HTTP_AUTHORIZATION'], 'Bearer') === 0 ? 'Bearer' : 'Basic';
+
+            $headers['WWW-Authenticate'] = $authScheme . ' realm="OAuth"';
        }
        // @codeCoverageIgnoreEnd
        return $headers;
    }

+    /**
+     * Check if the exception has an associated redirect URI.
+     *
+     * Returns whether the exception includes a redirect, since
+     * getHttpStatusCode() doesn't return a 302 when there's a
+     * redirect enabled. This helps when you want to override local
+     * error pages but want to let redirects through.
+     *
+     * @return bool
+     */
+    public function hasRedirect()
+    {
+        return $this->redirectUri !== null;
+    }
+
    /**
     * Returns the HTTP status code to send when the exceptions is output.
     *
--- a/src/Exception/UniqueTokenIdentifierConstraintViolationException.php
+++ b/src/Exception/UniqueTokenIdentifierConstraintViolationException.php
@@ -9,9 +9,11 @@

 namespace League\OAuth2\Server\Exception;

-
 class UniqueTokenIdentifierConstraintViolationException extends OAuthServerException
 {
+    /**
+     * @return UniqueTokenIdentifierConstraintViolationException
+     */
    public static function create()
    {
        $errorMessage = 'Could not create unique access token identifier';
--- a/src/Grant/AbstractGrant.php
+++ b/src/Grant/AbstractGrant.php
@@ -10,10 +10,17 @@
 */
 namespace League\OAuth2\Server\Grant;

+use DateInterval;
+use DateTime;
+use Error;
+use Exception;
 use League\Event\EmitterAwareTrait;
+use League\OAuth2\Server\CryptKey;
 use League\OAuth2\Server\CryptTrait;
 use League\OAuth2\Server\Entities\AccessTokenEntityInterface;
+use League\OAuth2\Server\Entities\AuthCodeEntityInterface;
 use League\OAuth2\Server\Entities\ClientEntityInterface;
+use League\OAuth2\Server\Entities\RefreshTokenEntityInterface;
 use League\OAuth2\Server\Entities\ScopeEntityInterface;
 use League\OAuth2\Server\Exception\OAuthServerException;
 use League\OAuth2\Server\Exception\UniqueTokenIdentifierConstraintViolationException;
@@ -25,7 +32,9 @@ use League\OAuth2\Server\Repositories\ScopeRepositoryInterface;
 use League\OAuth2\Server\Repositories\UserRepositoryInterface;
 use League\OAuth2\Server\RequestEvent;
 use League\OAuth2\Server\RequestTypes\AuthorizationRequest;
+use LogicException;
 use Psr\Http\Message\ServerRequestInterface;
+use TypeError;

 /**
 * Abstract grant class.
@@ -54,25 +63,35 @@ abstract class AbstractGrant implements GrantTypeInterface
    protected $scopeRepository;

    /**
-     * @var \League\OAuth2\Server\Repositories\AuthCodeRepositoryInterface
+     * @var AuthCodeRepositoryInterface
     */
    protected $authCodeRepository;

    /**
-     * @var \League\OAuth2\Server\Repositories\RefreshTokenRepositoryInterface
+     * @var RefreshTokenRepositoryInterface
     */
    protected $refreshTokenRepository;

    /**
-     * @var \League\OAuth2\Server\Repositories\UserRepositoryInterface
+     * @var UserRepositoryInterface
     */
    protected $userRepository;

    /**
-     * @var \DateInterval
+     * @var DateInterval
     */
    protected $refreshTokenTTL;

+    /**
+     * @var CryptKey
+     */
+    protected $privateKey;
+
+    /**
+     * @string
+     */
+    protected $defaultScope;
+
    /**
     * @param ClientRepositoryInterface $clientRepository
     */
@@ -98,7 +117,7 @@ abstract class AbstractGrant implements GrantTypeInterface
    }

    /**
-     * @param \League\OAuth2\Server\Repositories\RefreshTokenRepositoryInterface $refreshTokenRepository
+     * @param RefreshTokenRepositoryInterface $refreshTokenRepository
     */
    public function setRefreshTokenRepository(RefreshTokenRepositoryInterface $refreshTokenRepository)
    {
@@ -106,7 +125,7 @@ abstract class AbstractGrant implements GrantTypeInterface
    }

    /**
-     * @param \League\OAuth2\Server\Repositories\AuthCodeRepositoryInterface $authCodeRepository
+     * @param AuthCodeRepositoryInterface $authCodeRepository
     */
    public function setAuthCodeRepository(AuthCodeRepositoryInterface $authCodeRepository)
    {
@@ -114,7 +133,7 @@ abstract class AbstractGrant implements GrantTypeInterface
    }

    /**
-     * @param \League\OAuth2\Server\Repositories\UserRepositoryInterface $userRepository
+     * @param UserRepositoryInterface $userRepository
     */
    public function setUserRepository(UserRepositoryInterface $userRepository)
    {
@@ -124,26 +143,44 @@ abstract class AbstractGrant implements GrantTypeInterface
    /**
     * {@inheritdoc}
     */
-    public function setRefreshTokenTTL(\DateInterval $refreshTokenTTL)
+    public function setRefreshTokenTTL(DateInterval $refreshTokenTTL)
    {
        $this->refreshTokenTTL = $refreshTokenTTL;
    }

+    /**
+     * Set the private key
+     *
+     * @param CryptKey $key
+     */
+    public function setPrivateKey(CryptKey $key)
+    {
+        $this->privateKey = $key;
+    }
+
+    /**
+     * @param string $scope
+     */
+    public function setDefaultScope($scope)
+    {
+        $this->defaultScope = $scope;
+    }
+
    /**
     * Validate the client.
     *
-     * @param \Psr\Http\Message\ServerRequestInterface $request
+     * @param ServerRequestInterface $request
     *
-     * @throws \League\OAuth2\Server\Exception\OAuthServerException
+     * @throws OAuthServerException
     *
-     * @return \League\OAuth2\Server\Entities\ClientEntityInterface
+     * @return ClientEntityInterface
     */
    protected function validateClient(ServerRequestInterface $request)
    {
        list($basicAuthUser, $basicAuthPassword) = $this->getBasicAuthCredentials($request);

        $clientId = $this->getRequestParameter('client_id', $request, $basicAuthUser);
-        if (is_null($clientId)) {
+        if ($clientId === null) {
            throw OAuthServerException::invalidRequest('client_id');
        }

@@ -157,73 +194,99 @@ abstract class AbstractGrant implements GrantTypeInterface
            true
        );

-        if (!$client instanceof ClientEntityInterface) {
+        if ($client instanceof ClientEntityInterface === false) {
            $this->getEmitter()->emit(new RequestEvent(RequestEvent::CLIENT_AUTHENTICATION_FAILED, $request));
            throw OAuthServerException::invalidClient();
        }

-        // If a redirect URI is provided ensure it matches what is pre-registered
        $redirectUri = $this->getRequestParameter('redirect_uri', $request, null);
+
        if ($redirectUri !== null) {
-            if (
-                is_string($client->getRedirectUri())
-                && (strcmp($client->getRedirectUri(), $redirectUri) !== 0)
-            ) {
-                $this->getEmitter()->emit(new RequestEvent(RequestEvent::CLIENT_AUTHENTICATION_FAILED, $request));
-                throw OAuthServerException::invalidClient();
-            } elseif (
-                is_array($client->getRedirectUri())
-                && in_array($redirectUri, $client->getRedirectUri()) === false
-            ) {
-                $this->getEmitter()->emit(new RequestEvent(RequestEvent::CLIENT_AUTHENTICATION_FAILED, $request));
-                throw OAuthServerException::invalidClient();
-            }
+            $this->validateRedirectUri($redirectUri, $client, $request);
        }

        return $client;
    }

+    /**
+     * Validate redirectUri from the request.
+     * If a redirect URI is provided ensure it matches what is pre-registered
+     *
+     * @param string                 $redirectUri
+     * @param ClientEntityInterface  $client
+     * @param ServerRequestInterface $request
+     *
+     * @throws OAuthServerException
+     */
+    protected function validateRedirectUri(
+        string $redirectUri,
+        ClientEntityInterface $client,
+        ServerRequestInterface $request
+    ) {
+        if (\is_string($client->getRedirectUri())
+            && (strcmp($client->getRedirectUri(), $redirectUri) !== 0)
+        ) {
+            $this->getEmitter()->emit(new RequestEvent(RequestEvent::CLIENT_AUTHENTICATION_FAILED, $request));
+            throw OAuthServerException::invalidClient();
+        } elseif (\is_array($client->getRedirectUri())
+            && \in_array($redirectUri, $client->getRedirectUri(), true) === false
+        ) {
+            $this->getEmitter()->emit(new RequestEvent(RequestEvent::CLIENT_AUTHENTICATION_FAILED, $request));
+            throw OAuthServerException::invalidClient();
+        }
+    }
+
    /**
     * Validate scopes in the request.
     *
-     * @param string $scopes
-     * @param string $redirectUri
+     * @param string|array $scopes
+     * @param string       $redirectUri
     *
-     * @throws \League\OAuth2\Server\Exception\OAuthServerException
+     * @throws OAuthServerException
     *
-     * @return \League\OAuth2\Server\Entities\ScopeEntityInterface[]
+     * @return ScopeEntityInterface[]
     */
-    public function validateScopes(
-        $scopes,
-        $redirectUri = null
-    ) {
-        $scopesList = array_filter(
-            explode(self::SCOPE_DELIMITER_STRING, trim($scopes)),
-            function ($scope) {
-                return !empty($scope);
-            }
-        );
+    public function validateScopes($scopes, $redirectUri = null)
+    {
+        if (!\is_array($scopes)) {
+            $scopes = $this->convertScopesQueryStringToArray($scopes);
+        }

-        $scopes = [];
-        foreach ($scopesList as $scopeItem) {
+        $validScopes = [];
+
+        foreach ($scopes as $scopeItem) {
            $scope = $this->scopeRepository->getScopeEntityByIdentifier($scopeItem);

-            if (!$scope instanceof ScopeEntityInterface) {
+            if ($scope instanceof ScopeEntityInterface === false) {
                throw OAuthServerException::invalidScope($scopeItem, $redirectUri);
            }

-            $scopes[] = $scope;
+            $validScopes[] = $scope;
        }

-        return $scopes;
+        return $validScopes;
+    }
+
+    /**
+     * Converts a scopes query string to an array to easily iterate for validation.
+     *
+     * @param string $scopes
+     *
+     * @return array
+     */
+    private function convertScopesQueryStringToArray($scopes)
+    {
+        return array_filter(explode(self::SCOPE_DELIMITER_STRING, trim($scopes)), function ($scope) {
+            return !empty($scope);
+        });
    }

    /**
     * Retrieve request parameter.
     *
-     * @param string                                   $parameter
-     * @param \Psr\Http\Message\ServerRequestInterface $request
-     * @param mixed                                    $default
+     * @param string                 $parameter
+     * @param ServerRequestInterface $request
+     * @param mixed                  $default
     *
     * @return null|string
     */
@@ -231,7 +294,7 @@ abstract class AbstractGrant implements GrantTypeInterface
    {
        $requestParameters = (array) $request->getParsedBody();

-        return isset($requestParameters[$parameter]) ? $requestParameters[$parameter] : $default;
+        return $requestParameters[$parameter] ?? $default;
    }

    /**
@@ -241,7 +304,8 @@ abstract class AbstractGrant implements GrantTypeInterface
     * not exist, or is otherwise an invalid HTTP Basic header, return
     * [null, null].
     *
-     * @param \Psr\Http\Message\ServerRequestInterface $request
+     * @param ServerRequestInterface $request
+     *
     * @return string[]|null[]
     */
    protected function getBasicAuthCredentials(ServerRequestInterface $request)
@@ -269,9 +333,9 @@ abstract class AbstractGrant implements GrantTypeInterface
    /**
     * Retrieve query string parameter.
     *
-     * @param string                                   $parameter
-     * @param \Psr\Http\Message\ServerRequestInterface $request
-     * @param mixed                                    $default
+     * @param string                 $parameter
+     * @param ServerRequestInterface $request
+     * @param mixed                  $default
     *
     * @return null|string
     */
@@ -283,9 +347,9 @@ abstract class AbstractGrant implements GrantTypeInterface
    /**
     * Retrieve cookie parameter.
     *
-     * @param string                                   $parameter
-     * @param \Psr\Http\Message\ServerRequestInterface $request
-     * @param mixed                                    $default
+     * @param string                 $parameter
+     * @param ServerRequestInterface $request
+     * @param mixed                  $default
     *
     * @return null|string
     */
@@ -297,9 +361,9 @@ abstract class AbstractGrant implements GrantTypeInterface
    /**
     * Retrieve server parameter.
     *
-     * @param string                                   $parameter
-     * @param \Psr\Http\Message\ServerRequestInterface $request
-     * @param mixed                                    $default
+     * @param string                 $parameter
+     * @param ServerRequestInterface $request
+     * @param mixed                  $default
     *
     * @return null|string
     */
@@ -311,15 +375,18 @@ abstract class AbstractGrant implements GrantTypeInterface
    /**
     * Issue an access token.
     *
-     * @param \DateInterval                                         $accessTokenTTL
-     * @param \League\OAuth2\Server\Entities\ClientEntityInterface  $client
-     * @param string                                                $userIdentifier
-     * @param \League\OAuth2\Server\Entities\ScopeEntityInterface[] $scopes
+     * @param DateInterval           $accessTokenTTL
+     * @param ClientEntityInterface  $client
+     * @param string|null            $userIdentifier
+     * @param ScopeEntityInterface[] $scopes
     *
-     * @return \League\OAuth2\Server\Entities\AccessTokenEntityInterface
+     * @throws OAuthServerException
+     * @throws UniqueTokenIdentifierConstraintViolationException
+     *
+     * @return AccessTokenEntityInterface
     */
    protected function issueAccessToken(
-        \DateInterval $accessTokenTTL,
+        DateInterval $accessTokenTTL,
        ClientEntityInterface $client,
        $userIdentifier,
        array $scopes = []
@@ -329,7 +396,7 @@ abstract class AbstractGrant implements GrantTypeInterface
        $accessToken = $this->accessTokenRepository->getNewToken($client, $scopes, $userIdentifier);
        $accessToken->setClient($client);
        $accessToken->setUserIdentifier($userIdentifier);
-        $accessToken->setExpiryDateTime((new \DateTime())->add($accessTokenTTL));
+        $accessToken->setExpiryDateTime((new DateTime())->add($accessTokenTTL));

        foreach ($scopes as $scope) {
            $accessToken->addScope($scope);
@@ -339,6 +406,7 @@ abstract class AbstractGrant implements GrantTypeInterface
            $accessToken->setIdentifier($this->generateUniqueIdentifier());
            try {
                $this->accessTokenRepository->persistNewAccessToken($accessToken);
+
                return $accessToken;
            } catch (UniqueTokenIdentifierConstraintViolationException $e) {
                if ($maxGenerationAttempts === 0) {
@@ -351,16 +419,19 @@ abstract class AbstractGrant implements GrantTypeInterface
    /**
     * Issue an auth code.
     *
-     * @param \DateInterval                                         $authCodeTTL
-     * @param \League\OAuth2\Server\Entities\ClientEntityInterface  $client
-     * @param string                                                $userIdentifier
-     * @param string                                                $redirectUri
-     * @param \League\OAuth2\Server\Entities\ScopeEntityInterface[] $scopes
+     * @param DateInterval           $authCodeTTL
+     * @param ClientEntityInterface  $client
+     * @param string                 $userIdentifier
+     * @param string|null            $redirectUri
+     * @param ScopeEntityInterface[] $scopes
     *
-     * @return \League\OAuth2\Server\Entities\AuthCodeEntityInterface
+     * @throws OAuthServerException
+     * @throws UniqueTokenIdentifierConstraintViolationException
+     *
+     * @return AuthCodeEntityInterface
     */
    protected function issueAuthCode(
-        \DateInterval $authCodeTTL,
+        DateInterval $authCodeTTL,
        ClientEntityInterface $client,
        $userIdentifier,
        $redirectUri,
@@ -369,10 +440,13 @@ abstract class AbstractGrant implements GrantTypeInterface
        $maxGenerationAttempts = self::MAX_RANDOM_TOKEN_GENERATION_ATTEMPTS;

        $authCode = $this->authCodeRepository->getNewAuthCode();
-        $authCode->setExpiryDateTime((new \DateTime())->add($authCodeTTL));
+        $authCode->setExpiryDateTime((new DateTime())->add($authCodeTTL));
        $authCode->setClient($client);
        $authCode->setUserIdentifier($userIdentifier);
-        $authCode->setRedirectUri($redirectUri);
+
+        if ($redirectUri !== null) {
+            $authCode->setRedirectUri($redirectUri);
+        }

        foreach ($scopes as $scope) {
            $authCode->addScope($scope);
@@ -382,6 +456,7 @@ abstract class AbstractGrant implements GrantTypeInterface
            $authCode->setIdentifier($this->generateUniqueIdentifier());
            try {
                $this->authCodeRepository->persistNewAuthCode($authCode);
+
                return $authCode;
            } catch (UniqueTokenIdentifierConstraintViolationException $e) {
                if ($maxGenerationAttempts === 0) {
@@ -392,22 +467,26 @@ abstract class AbstractGrant implements GrantTypeInterface
    }

    /**
-     * @param \League\OAuth2\Server\Entities\AccessTokenEntityInterface $accessToken
+     * @param AccessTokenEntityInterface $accessToken
     *
-     * @return \League\OAuth2\Server\Entities\RefreshTokenEntityInterface
+     * @throws OAuthServerException
+     * @throws UniqueTokenIdentifierConstraintViolationException
+     *
+     * @return RefreshTokenEntityInterface
     */
    protected function issueRefreshToken(AccessTokenEntityInterface $accessToken)
    {
        $maxGenerationAttempts = self::MAX_RANDOM_TOKEN_GENERATION_ATTEMPTS;

        $refreshToken = $this->refreshTokenRepository->getNewRefreshToken();
-        $refreshToken->setExpiryDateTime((new \DateTime())->add($this->refreshTokenTTL));
+        $refreshToken->setExpiryDateTime((new DateTime())->add($this->refreshTokenTTL));
        $refreshToken->setAccessToken($accessToken);

        while ($maxGenerationAttempts-- > 0) {
            $refreshToken->setIdentifier($this->generateUniqueIdentifier());
            try {
                $this->refreshTokenRepository->persistNewRefreshToken($refreshToken);
+
                return $refreshToken;
            } catch (UniqueTokenIdentifierConstraintViolationException $e) {
                if ($maxGenerationAttempts === 0) {
@@ -422,7 +501,7 @@ abstract class AbstractGrant implements GrantTypeInterface
     *
     * @param int $length
     *
-     * @throws \League\OAuth2\Server\Exception\OAuthServerException
+     * @throws OAuthServerException
     *
     * @return string
     */
@@ -431,13 +510,13 @@ abstract class AbstractGrant implements GrantTypeInterface
        try {
            return bin2hex(random_bytes($length));
            // @codeCoverageIgnoreStart
-        } catch (\TypeError $e) {
-            throw OAuthServerException::serverError('An unexpected error has occurred');
-        } catch (\Error $e) {
-            throw OAuthServerException::serverError('An unexpected error has occurred');
-        } catch (\Exception $e) {
+        } catch (TypeError $e) {
+            throw OAuthServerException::serverError('An unexpected error has occurred', $e);
+        } catch (Error $e) {
+            throw OAuthServerException::serverError('An unexpected error has occurred', $e);
+        } catch (Exception $e) {
            // If you get this message, the CSPRNG failed hard.
-            throw OAuthServerException::serverError('Could not generate a random string');
+            throw OAuthServerException::serverError('Could not generate a random string', $e);
        }
        // @codeCoverageIgnoreEnd
    }
@@ -468,7 +547,7 @@ abstract class AbstractGrant implements GrantTypeInterface
     */
    public function validateAuthorizationRequest(ServerRequestInterface $request)
    {
-        throw new \LogicException('This grant cannot validate an authorization request');
+        throw new LogicException('This grant cannot validate an authorization request');
    }

    /**
@@ -476,6 +555,6 @@ abstract class AbstractGrant implements GrantTypeInterface
     */
    public function completeAuthorizationRequest(AuthorizationRequest $authorizationRequest)
    {
-        throw new \LogicException('This grant cannot complete an authorization request');
+        throw new LogicException('This grant cannot complete an authorization request');
    }
 }
--- a/src/Grant/AuthCodeGrant.php
+++ b/src/Grant/AuthCodeGrant.php
@@ -10,8 +10,9 @@
 namespace League\OAuth2\Server\Grant;

 use DateInterval;
+use DateTime;
+use Exception;
 use League\OAuth2\Server\Entities\ClientEntityInterface;
-use League\OAuth2\Server\Entities\ScopeEntityInterface;
 use League\OAuth2\Server\Entities\UserEntityInterface;
 use League\OAuth2\Server\Exception\OAuthServerException;
 use League\OAuth2\Server\Repositories\AuthCodeRepositoryInterface;
@@ -20,12 +21,14 @@ use League\OAuth2\Server\RequestEvent;
 use League\OAuth2\Server\RequestTypes\AuthorizationRequest;
 use League\OAuth2\Server\ResponseTypes\RedirectResponse;
 use League\OAuth2\Server\ResponseTypes\ResponseTypeInterface;
+use LogicException;
 use Psr\Http\Message\ServerRequestInterface;
+use stdClass;

 class AuthCodeGrant extends AbstractAuthorizeGrant
 {
    /**
-     * @var \DateInterval
+     * @var DateInterval
     */
    private $authCodeTTL;

@@ -35,19 +38,21 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
    private $enableCodeExchangeProof = false;

    /**
-     * @param \League\OAuth2\Server\Repositories\AuthCodeRepositoryInterface     $authCodeRepository
-     * @param \League\OAuth2\Server\Repositories\RefreshTokenRepositoryInterface $refreshTokenRepository
-     * @param \DateInterval                                                      $authCodeTTL
+     * @param AuthCodeRepositoryInterface     $authCodeRepository
+     * @param RefreshTokenRepositoryInterface $refreshTokenRepository
+     * @param DateInterval                    $authCodeTTL
+     *
+     * @throws Exception
     */
    public function __construct(
        AuthCodeRepositoryInterface $authCodeRepository,
        RefreshTokenRepositoryInterface $refreshTokenRepository,
-        \DateInterval $authCodeTTL
+        DateInterval $authCodeTTL
    ) {
        $this->setAuthCodeRepository($authCodeRepository);
        $this->setRefreshTokenRepository($refreshTokenRepository);
        $this->authCodeTTL = $authCodeTTL;
-        $this->refreshTokenTTL = new \DateInterval('P1M');
+        $this->refreshTokenTTL = new DateInterval('P1M');
    }

    public function enableCodeExchangeProof()
@@ -58,13 +63,13 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
    /**
     * Respond to an access token request.
     *
-     * @param \Psr\Http\Message\ServerRequestInterface                  $request
-     * @param \League\OAuth2\Server\ResponseTypes\ResponseTypeInterface $responseType
-     * @param \DateInterval                                             $accessTokenTTL
+     * @param ServerRequestInterface $request
+     * @param ResponseTypeInterface  $responseType
+     * @param DateInterval           $accessTokenTTL
     *
-     * @throws \League\OAuth2\Server\Exception\OAuthServerException
+     * @throws OAuthServerException
     *
-     * @return \League\OAuth2\Server\ResponseTypes\ResponseTypeInterface
+     * @return ResponseTypeInterface
     */
    public function respondToAccessTokenRequest(
        ServerRequestInterface $request,
@@ -79,62 +84,38 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
            throw OAuthServerException::invalidRequest('code');
        }

-        // Validate the authorization code
        try {
            $authCodePayload = json_decode($this->decrypt($encryptedAuthCode));
-            if (time() > $authCodePayload->expire_time) {
-                throw OAuthServerException::invalidRequest('code', 'Authorization code has expired');
-            }

-            if ($this->authCodeRepository->isAuthCodeRevoked($authCodePayload->auth_code_id) === true) {
-                throw OAuthServerException::invalidRequest('code', 'Authorization code has been revoked');
-            }
+            $this->validateAuthorizationCode($authCodePayload, $client, $request);

-            if ($authCodePayload->client_id !== $client->getIdentifier()) {
-                throw OAuthServerException::invalidRequest('code', 'Authorization code was not issued to this client');
-            }
-
-            // The redirect URI is required in this request
-            $redirectUri = $this->getRequestParameter('redirect_uri', $request, null);
-            if (empty($authCodePayload->redirect_uri) === false && $redirectUri === null) {
-                throw OAuthServerException::invalidRequest('redirect_uri');
-            }
-
-            if ($authCodePayload->redirect_uri !== $redirectUri) {
-                throw OAuthServerException::invalidRequest('redirect_uri', 'Invalid redirect URI');
-            }
-
-            $scopes = [];
-            foreach ($authCodePayload->scopes as $scopeId) {
-                $scope = $this->scopeRepository->getScopeEntityByIdentifier($scopeId);
-
-                if (!$scope instanceof ScopeEntityInterface) {
-                    // @codeCoverageIgnoreStart
-                    throw OAuthServerException::invalidScope($scopeId);
-                    // @codeCoverageIgnoreEnd
-                }
-
-                $scopes[] = $scope;
-            }
-
-            // Finalize the requested scopes
            $scopes = $this->scopeRepository->finalizeScopes(
-                $scopes,
+                $this->validateScopes($authCodePayload->scopes),
                $this->getIdentifier(),
                $client,
                $authCodePayload->user_id
            );
-        } catch (\LogicException  $e) {
-            throw OAuthServerException::invalidRequest('code', 'Cannot decrypt the authorization code');
+        } catch (LogicException $e) {
+            throw OAuthServerException::invalidRequest('code', 'Cannot decrypt the authorization code', $e);
        }

        // Validate code challenge
        if ($this->enableCodeExchangeProof === true) {
            $codeVerifier = $this->getRequestParameter('code_verifier', $request, null);
+
            if ($codeVerifier === null) {
                throw OAuthServerException::invalidRequest('code_verifier');
            }

+            // Validate code_verifier according to RFC-7636
+            // @see: https://tools.ietf.org/html/rfc7636#section-4.1
+            if (preg_match('/^[A-Za-z0-9-._~]{43,128}$/', $codeVerifier) !== 1) {
+                throw OAuthServerException::invalidRequest(
+                    'code_verifier',
+                    'Code Verifier must follow the specifications of RFC-7636.'
+                );
+            }
+
            switch ($authCodePayload->code_challenge_method) {
                case 'plain':
                    if (hash_equals($codeVerifier, $authCodePayload->code_challenge) === false) {
@@ -145,7 +126,7 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
                case 'S256':
                    if (
                        hash_equals(
-                            urlencode(base64_encode(hash('sha256', $codeVerifier))),
+                            strtr(rtrim(base64_encode(hash('sha256', $codeVerifier, true)), '='), '+/', '-_'),
                            $authCodePayload->code_challenge
                        ) === false
                    ) {
@@ -168,6 +149,10 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
        $accessToken = $this->issueAccessToken($accessTokenTTL, $client, $authCodePayload->user_id, $scopes);
        $refreshToken = $this->issueRefreshToken($accessToken);

+        // Send events to emitter
+        $this->getEmitter()->emit(new RequestEvent(RequestEvent::ACCESS_TOKEN_ISSUED, $request));
+        $this->getEmitter()->emit(new RequestEvent(RequestEvent::REFRESH_TOKEN_ISSUED, $request));
+
        // Inject tokens into response type
        $responseType->setAccessToken($accessToken);
        $responseType->setRefreshToken($refreshToken);
@@ -178,6 +163,41 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
        return $responseType;
    }

+    /**
+     * Validate the authorization code.
+     *
+     * @param stdClass               $authCodePayload
+     * @param ClientEntityInterface  $client
+     * @param ServerRequestInterface $request
+     */
+    private function validateAuthorizationCode(
+        $authCodePayload,
+        ClientEntityInterface $client,
+        ServerRequestInterface $request
+    ) {
+        if (time() > $authCodePayload->expire_time) {
+            throw OAuthServerException::invalidRequest('code', 'Authorization code has expired');
+        }
+
+        if ($this->authCodeRepository->isAuthCodeRevoked($authCodePayload->auth_code_id) === true) {
+            throw OAuthServerException::invalidRequest('code', 'Authorization code has been revoked');
+        }
+
+        if ($authCodePayload->client_id !== $client->getIdentifier()) {
+            throw OAuthServerException::invalidRequest('code', 'Authorization code was not issued to this client');
+        }
+
+        // The redirect URI is required in this request
+        $redirectUri = $this->getRequestParameter('redirect_uri', $request, null);
+        if (empty($authCodePayload->redirect_uri) === false && $redirectUri === null) {
+            throw OAuthServerException::invalidRequest('redirect_uri');
+        }
+
+        if ($authCodePayload->redirect_uri !== $redirectUri) {
+            throw OAuthServerException::invalidRequest('redirect_uri', 'Invalid redirect URI');
+        }
+    }
+
    /**
     * Return the grant identifier that can be used in matching up requests.
     *
@@ -210,7 +230,8 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
            $request,
            $this->getServerParameter('PHP_AUTH_USER', $request)
        );
-        if (is_null($clientId)) {
+
+        if ($clientId === null) {
            throw OAuthServerException::invalidRequest('client_id');
        }

@@ -227,27 +248,22 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
        }

        $redirectUri = $this->getQueryStringParameter('redirect_uri', $request);
+
        if ($redirectUri !== null) {
-            if (
-                is_string($client->getRedirectUri())
-                && (strcmp($client->getRedirectUri(), $redirectUri) !== 0)
-            ) {
-                $this->getEmitter()->emit(new RequestEvent(RequestEvent::CLIENT_AUTHENTICATION_FAILED, $request));
-                throw OAuthServerException::invalidClient();
-            } elseif (
-                is_array($client->getRedirectUri())
-                && in_array($redirectUri, $client->getRedirectUri()) === false
-            ) {
-                $this->getEmitter()->emit(new RequestEvent(RequestEvent::CLIENT_AUTHENTICATION_FAILED, $request));
-                throw OAuthServerException::invalidClient();
-            }
+            $this->validateRedirectUri($redirectUri, $client, $request);
+        } elseif (empty($client->getRedirectUri()) ||
+            (\is_array($client->getRedirectUri()) && \count($client->getRedirectUri()) !== 1)) {
+            $this->getEmitter()->emit(new RequestEvent(RequestEvent::CLIENT_AUTHENTICATION_FAILED, $request));
+            throw OAuthServerException::invalidClient();
+        } else {
+            $redirectUri = \is_array($client->getRedirectUri())
+                ? $client->getRedirectUri()[0]
+                : $client->getRedirectUri();
        }

        $scopes = $this->validateScopes(
-            $this->getQueryStringParameter('scope', $request),
-            is_array($client->getRedirectUri())
-                ? $client->getRedirectUri()[0]
-                : $client->getRedirectUri()
+            $this->getQueryStringParameter('scope', $request, $this->defaultScope),
+            $redirectUri
        );

        $stateParameter = $this->getQueryStringParameter('state', $request);
@@ -256,7 +272,11 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
        $authorizationRequest->setGrantTypeId($this->getIdentifier());
        $authorizationRequest->setClient($client);
        $authorizationRequest->setRedirectUri($redirectUri);
-        $authorizationRequest->setState($stateParameter);
+
+        if ($stateParameter !== null) {
+            $authorizationRequest->setState($stateParameter);
+        }
+
        $authorizationRequest->setScopes($scopes);

        if ($this->enableCodeExchangeProof === true) {
@@ -266,13 +286,23 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
            }

            $codeChallengeMethod = $this->getQueryStringParameter('code_challenge_method', $request, 'plain');
-            if (in_array($codeChallengeMethod, ['plain', 'S256']) === false) {
+
+            if (\in_array($codeChallengeMethod, ['plain', 'S256'], true) === false) {
                throw OAuthServerException::invalidRequest(
                    'code_challenge_method',
                    'Code challenge method must be `plain` or `S256`'
                );
            }

+            // Validate code_challenge according to RFC-7636
+            // @see: https://tools.ietf.org/html/rfc7636#section-4.2
+            if (preg_match('/^[A-Za-z0-9-._~]{43,128}$/', $codeChallenge) !== 1) {
+                throw OAuthServerException::invalidRequest(
+                    'code_challenged',
+                    'Code challenge must follow the specifications of RFC-7636.'
+                );
+            }
+
            $authorizationRequest->setCodeChallenge($codeChallenge);
            $authorizationRequest->setCodeChallengeMethod($codeChallengeMethod);
        }
@@ -286,14 +316,11 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
    public function completeAuthorizationRequest(AuthorizationRequest $authorizationRequest)
    {
        if ($authorizationRequest->getUser() instanceof UserEntityInterface === false) {
-            throw new \LogicException('An instance of UserEntityInterface should be set on the AuthorizationRequest');
+            throw new LogicException('An instance of UserEntityInterface should be set on the AuthorizationRequest');
        }

-        $finalRedirectUri = ($authorizationRequest->getRedirectUri() === null)
-            ? is_array($authorizationRequest->getClient()->getRedirectUri())
-                ? $authorizationRequest->getClient()->getRedirectUri()[0]
-                : $authorizationRequest->getClient()->getRedirectUri()
-            : $authorizationRequest->getRedirectUri();
+        $finalRedirectUri = $authorizationRequest->getRedirectUri()
+                          ?? $this->getClientRedirectUri($authorizationRequest);

        // The user approved the client, redirect them back with an auth code
        if ($authorizationRequest->isAuthorizationApproved() === true) {
@@ -305,6 +332,17 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
                $authorizationRequest->getScopes()
            );

+            $payload = [
+                'client_id'             => $authCode->getClient()->getIdentifier(),
+                'redirect_uri'          => $authCode->getRedirectUri(),
+                'auth_code_id'          => $authCode->getIdentifier(),
+                'scopes'                => $authCode->getScopes(),
+                'user_id'               => $authCode->getUserIdentifier(),
+                'expire_time'           => (new DateTime())->add($this->authCodeTTL)->format('U'),
+                'code_challenge'        => $authorizationRequest->getCodeChallenge(),
+                'code_challenge_method' => $authorizationRequest->getCodeChallengeMethod(),
+            ];
+
            $response = new RedirectResponse();
            $response->setRedirectUri(
                $this->makeRedirectUri(
@@ -312,16 +350,7 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
                    [
                        'code'  => $this->encrypt(
                            json_encode(
-                                [
-                                    'client_id'               => $authCode->getClient()->getIdentifier(),
-                                    'redirect_uri'            => $authCode->getRedirectUri(),
-                                    'auth_code_id'            => $authCode->getIdentifier(),
-                                    'scopes'                  => $authCode->getScopes(),
-                                    'user_id'                 => $authCode->getUserIdentifier(),
-                                    'expire_time'             => (new \DateTime())->add($this->authCodeTTL)->format('U'),
-                                    'code_challenge'          => $authorizationRequest->getCodeChallenge(),
-                                    'code_challenge_method  ' => $authorizationRequest->getCodeChallengeMethod(),
-                                ]
+                                $payload
                            )
                        ),
                        'state' => $authorizationRequest->getState(),
@@ -343,4 +372,18 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
            )
        );
    }
+
+    /**
+     * Get the client redirect URI if not set in the request.
+     *
+     * @param AuthorizationRequest $authorizationRequest
+     *
+     * @return string
+     */
+    private function getClientRedirectUri(AuthorizationRequest $authorizationRequest)
+    {
+        return \is_array($authorizationRequest->getClient()->getRedirectUri())
+                ? $authorizationRequest->getClient()->getRedirectUri()[0]
+                : $authorizationRequest->getClient()->getRedirectUri();
+    }
 }
--- a/src/Grant/ClientCredentialsGrant.php
+++ b/src/Grant/ClientCredentialsGrant.php
@@ -8,8 +8,11 @@
 *
 * @link        https://github.com/thephpleague/oauth2-server
 */
+
 namespace League\OAuth2\Server\Grant;

+use DateInterval;
+use League\OAuth2\Server\RequestEvent;
 use League\OAuth2\Server\ResponseTypes\ResponseTypeInterface;
 use Psr\Http\Message\ServerRequestInterface;

@@ -24,17 +27,20 @@ class ClientCredentialsGrant extends AbstractGrant
    public function respondToAccessTokenRequest(
        ServerRequestInterface $request,
        ResponseTypeInterface $responseType,
-        \DateInterval $accessTokenTTL
+        DateInterval $accessTokenTTL
    ) {
        // Validate request
        $client = $this->validateClient($request);
-        $scopes = $this->validateScopes($this->getRequestParameter('scope', $request));
+        $scopes = $this->validateScopes($this->getRequestParameter('scope', $request, $this->defaultScope));

        // Finalize the requested scopes
-        $scopes = $this->scopeRepository->finalizeScopes($scopes, $this->getIdentifier(), $client);
+        $finalizedScopes = $this->scopeRepository->finalizeScopes($scopes, $this->getIdentifier(), $client);

        // Issue and persist access token
-        $accessToken = $this->issueAccessToken($accessTokenTTL, $client, null, $scopes);
+        $accessToken = $this->issueAccessToken($accessTokenTTL, $client, null, $finalizedScopes);
+
+        // Send event to emitter
+        $this->getEmitter()->emit(new RequestEvent(RequestEvent::ACCESS_TOKEN_ISSUED, $request));

        // Inject access token into response type
        $responseType->setAccessToken($accessToken);
--- a/src/Grant/GrantTypeInterface.php
+++ b/src/Grant/GrantTypeInterface.php
@@ -8,8 +8,11 @@
 *
 * @link        https://github.com/thephpleague/oauth2-server
 */
+
 namespace League\OAuth2\Server\Grant;

+use DateInterval;
+use Defuse\Crypto\Key;
 use League\Event\EmitterAwareInterface;
 use League\OAuth2\Server\CryptKey;
 use League\OAuth2\Server\Repositories\AccessTokenRepositoryInterface;
@@ -27,9 +30,9 @@ interface GrantTypeInterface extends EmitterAwareInterface
    /**
     * Set refresh token TTL.
     *
-     * @param \DateInterval $refreshTokenTTL
+     * @param DateInterval $refreshTokenTTL
     */
-    public function setRefreshTokenTTL(\DateInterval $refreshTokenTTL);
+    public function setRefreshTokenTTL(DateInterval $refreshTokenTTL);

    /**
     * Return the grant identifier that can be used in matching up requests.
@@ -41,22 +44,22 @@ interface GrantTypeInterface extends EmitterAwareInterface
    /**
     * Respond to an incoming request.
     *
-     * @param \Psr\Http\Message\ServerRequestInterface                  $request
-     * @param \League\OAuth2\Server\ResponseTypes\ResponseTypeInterface $responseType
-     * @param \DateInterval                                             $accessTokenTTL
+     * @param ServerRequestInterface $request
+     * @param ResponseTypeInterface  $responseType
+     * @param DateInterval           $accessTokenTTL
     *
-     * @return \League\OAuth2\Server\ResponseTypes\ResponseTypeInterface
+     * @return ResponseTypeInterface
     */
    public function respondToAccessTokenRequest(
        ServerRequestInterface $request,
        ResponseTypeInterface $responseType,
-        \DateInterval $accessTokenTTL
+        DateInterval $accessTokenTTL
    );

    /**
     * The grant type should return true if it is able to response to an authorization request
     *
-     * @param \Psr\Http\Message\ServerRequestInterface $request
+     * @param ServerRequestInterface $request
     *
     * @return bool
     */
@@ -69,7 +72,7 @@ interface GrantTypeInterface extends EmitterAwareInterface
     * If the validation is successful an AuthorizationRequest object will be returned. This object can be safely
     * serialized in a user's session, and can be used during user authentication and authorization.
     *
-     * @param \Psr\Http\Message\ServerRequestInterface $request
+     * @param ServerRequestInterface $request
     *
     * @return AuthorizationRequest
     */
@@ -80,9 +83,9 @@ interface GrantTypeInterface extends EmitterAwareInterface
     * The AuthorizationRequest object's $userId property must be set to the authenticated user and the
     * $authorizationApproved property must reflect their desire to authorize or deny the client.
     *
-     * @param \League\OAuth2\Server\RequestTypes\AuthorizationRequest $authorizationRequest
+     * @param AuthorizationRequest $authorizationRequest
     *
-     * @return \League\OAuth2\Server\ResponseTypes\ResponseTypeInterface
+     * @return ResponseTypeInterface
     */
    public function completeAuthorizationRequest(AuthorizationRequest $authorizationRequest);

@@ -91,7 +94,7 @@ interface GrantTypeInterface extends EmitterAwareInterface
     *
     * For example most grant types will check that the $_POST['grant_type'] property matches it's identifier property.
     *
-     * @param \Psr\Http\Message\ServerRequestInterface $request
+     * @param ServerRequestInterface $request
     *
     * @return bool
     */
@@ -100,35 +103,42 @@ interface GrantTypeInterface extends EmitterAwareInterface
    /**
     * Set the client repository.
     *
-     * @param \League\OAuth2\Server\Repositories\ClientRepositoryInterface $clientRepository
+     * @param ClientRepositoryInterface $clientRepository
     */
    public function setClientRepository(ClientRepositoryInterface $clientRepository);

    /**
     * Set the access token repository.
     *
-     * @param \League\OAuth2\Server\Repositories\AccessTokenRepositoryInterface $accessTokenRepository
+     * @param AccessTokenRepositoryInterface $accessTokenRepository
     */
    public function setAccessTokenRepository(AccessTokenRepositoryInterface $accessTokenRepository);

    /**
     * Set the scope repository.
     *
-     * @param \League\OAuth2\Server\Repositories\ScopeRepositoryInterface $scopeRepository
+     * @param ScopeRepositoryInterface $scopeRepository
     */
    public function setScopeRepository(ScopeRepositoryInterface $scopeRepository);

+    /**
+     * Set the default scope.
+     *
+     * @param string $scope
+     */
+    public function setDefaultScope($scope);
+
    /**
     * Set the path to the private key.
     *
-     * @param \League\OAuth2\Server\CryptKey $privateKey
+     * @param CryptKey $privateKey
     */
    public function setPrivateKey(CryptKey $privateKey);

    /**
-     * Set the path to the public key.
+     * Set the encryption key
     *
-     * @param \League\OAuth2\Server\CryptKey $publicKey
+     * @param string|Key|null $key
     */
-    public function setPublicKey(CryptKey $publicKey);
+    public function setEncryptionKey($key = null);
 }
--- a/src/Grant/ImplicitGrant.php
+++ b/src/Grant/ImplicitGrant.php
@@ -9,6 +9,8 @@

 namespace League\OAuth2\Server\Grant;

+use DateInterval;
+use DateTime;
 use League\OAuth2\Server\Entities\ClientEntityInterface;
 use League\OAuth2\Server\Entities\UserEntityInterface;
 use League\OAuth2\Server\Exception\OAuthServerException;
@@ -17,41 +19,49 @@ use League\OAuth2\Server\RequestEvent;
 use League\OAuth2\Server\RequestTypes\AuthorizationRequest;
 use League\OAuth2\Server\ResponseTypes\RedirectResponse;
 use League\OAuth2\Server\ResponseTypes\ResponseTypeInterface;
+use LogicException;
 use Psr\Http\Message\ServerRequestInterface;

 class ImplicitGrant extends AbstractAuthorizeGrant
 {
    /**
-     * @var \DateInterval
+     * @var DateInterval
     */
    private $accessTokenTTL;

    /**
-     * @param \DateInterval $accessTokenTTL
+     * @var string
     */
-    public function __construct(\DateInterval $accessTokenTTL)
+    private $queryDelimiter;
+
+    /**
+     * @param DateInterval $accessTokenTTL
+     * @param string       $queryDelimiter
+     */
+    public function __construct(DateInterval $accessTokenTTL, $queryDelimiter = '#')
    {
        $this->accessTokenTTL = $accessTokenTTL;
+        $this->queryDelimiter = $queryDelimiter;
    }

    /**
-     * @param \DateInterval $refreshTokenTTL
+     * @param DateInterval $refreshTokenTTL
     *
-     * @throw \LogicException
+     * @throw LogicException
     */
-    public function setRefreshTokenTTL(\DateInterval $refreshTokenTTL)
+    public function setRefreshTokenTTL(DateInterval $refreshTokenTTL)
    {
-        throw new \LogicException('The Implicit Grant does not return refresh tokens');
+        throw new LogicException('The Implicit Grant does not return refresh tokens');
    }

    /**
-     * @param \League\OAuth2\Server\Repositories\RefreshTokenRepositoryInterface $refreshTokenRepository
+     * @param RefreshTokenRepositoryInterface $refreshTokenRepository
     *
-     * @throw \LogicException
+     * @throw LogicException
     */
    public function setRefreshTokenRepository(RefreshTokenRepositoryInterface $refreshTokenRepository)
    {
-        throw new \LogicException('The Implicit Grant does not return refresh tokens');
+        throw new LogicException('The Implicit Grant does not return refresh tokens');
    }

    /**
@@ -75,18 +85,18 @@ class ImplicitGrant extends AbstractAuthorizeGrant
    /**
     * Respond to an incoming request.
     *
-     * @param \Psr\Http\Message\ServerRequestInterface                  $request
-     * @param \League\OAuth2\Server\ResponseTypes\ResponseTypeInterface $responseType
-     * @param \DateInterval                                             $accessTokenTTL
+     * @param ServerRequestInterface $request
+     * @param ResponseTypeInterface  $responseType
+     * @param DateInterval           $accessTokenTTL
     *
-     * @return \League\OAuth2\Server\ResponseTypes\ResponseTypeInterface
+     * @return ResponseTypeInterface
     */
    public function respondToAccessTokenRequest(
        ServerRequestInterface $request,
        ResponseTypeInterface $responseType,
-        \DateInterval $accessTokenTTL
+        DateInterval $accessTokenTTL
    ) {
-        throw new \LogicException('This grant does not used this method');
+        throw new LogicException('This grant does not used this method');
    }

    /**
@@ -95,7 +105,7 @@ class ImplicitGrant extends AbstractAuthorizeGrant
    public function canRespondToAuthorizationRequest(ServerRequestInterface $request)
    {
        return (
-            array_key_exists('response_type', $request->getQueryParams())
+            isset($request->getQueryParams()['response_type'])
            && $request->getQueryParams()['response_type'] === 'token'
            && isset($request->getQueryParams()['client_id'])
        );
@@ -111,6 +121,7 @@ class ImplicitGrant extends AbstractAuthorizeGrant
            $request,
            $this->getServerParameter('PHP_AUTH_USER', $request)
        );
+
        if (is_null($clientId)) {
            throw OAuthServerException::invalidRequest('client_id');
        }
@@ -128,27 +139,22 @@ class ImplicitGrant extends AbstractAuthorizeGrant
        }

        $redirectUri = $this->getQueryStringParameter('redirect_uri', $request);
+
        if ($redirectUri !== null) {
-            if (
-                is_string($client->getRedirectUri())
-                && (strcmp($client->getRedirectUri(), $redirectUri) !== 0)
-            ) {
-                $this->getEmitter()->emit(new RequestEvent(RequestEvent::CLIENT_AUTHENTICATION_FAILED, $request));
-                throw OAuthServerException::invalidClient();
-            } elseif (
-                is_array($client->getRedirectUri())
-                && in_array($redirectUri, $client->getRedirectUri()) === false
-            ) {
-                $this->getEmitter()->emit(new RequestEvent(RequestEvent::CLIENT_AUTHENTICATION_FAILED, $request));
-                throw OAuthServerException::invalidClient();
-            }
+            $this->validateRedirectUri($redirectUri, $client, $request);
+        } elseif (is_array($client->getRedirectUri()) && count($client->getRedirectUri()) !== 1
+            || empty($client->getRedirectUri())) {
+            $this->getEmitter()->emit(new RequestEvent(RequestEvent::CLIENT_AUTHENTICATION_FAILED, $request));
+            throw OAuthServerException::invalidClient();
+        } else {
+            $redirectUri = is_array($client->getRedirectUri())
+                ? $client->getRedirectUri()[0]
+                : $client->getRedirectUri();
        }

        $scopes = $this->validateScopes(
-            $this->getQueryStringParameter('scope', $request),
-            is_array($client->getRedirectUri())
-                ? $client->getRedirectUri()[0]
-                : $client->getRedirectUri()
+            $this->getQueryStringParameter('scope', $request, $this->defaultScope),
+            $redirectUri
        );

        $stateParameter = $this->getQueryStringParameter('state', $request);
@@ -157,7 +163,11 @@ class ImplicitGrant extends AbstractAuthorizeGrant
        $authorizationRequest->setGrantTypeId($this->getIdentifier());
        $authorizationRequest->setClient($client);
        $authorizationRequest->setRedirectUri($redirectUri);
-        $authorizationRequest->setState($stateParameter);
+
+        if ($stateParameter !== null) {
+            $authorizationRequest->setState($stateParameter);
+        }
+
        $authorizationRequest->setScopes($scopes);

        return $authorizationRequest;
@@ -169,7 +179,7 @@ class ImplicitGrant extends AbstractAuthorizeGrant
    public function completeAuthorizationRequest(AuthorizationRequest $authorizationRequest)
    {
        if ($authorizationRequest->getUser() instanceof UserEntityInterface === false) {
-            throw new \LogicException('An instance of UserEntityInterface should be set on the AuthorizationRequest');
+            throw new LogicException('An instance of UserEntityInterface should be set on the AuthorizationRequest');
        }

        $finalRedirectUri = ($authorizationRequest->getRedirectUri() === null)
@@ -180,11 +190,19 @@ class ImplicitGrant extends AbstractAuthorizeGrant

        // The user approved the client, redirect them back with an access token
        if ($authorizationRequest->isAuthorizationApproved() === true) {
+            // Finalize the requested scopes
+            $finalizedScopes = $this->scopeRepository->finalizeScopes(
+                $authorizationRequest->getScopes(),
+                $this->getIdentifier(),
+                $authorizationRequest->getClient(),
+                $authorizationRequest->getUser()->getIdentifier()
+            );
+
            $accessToken = $this->issueAccessToken(
                $this->accessTokenTTL,
                $authorizationRequest->getClient(),
                $authorizationRequest->getUser()->getIdentifier(),
-                $authorizationRequest->getScopes()
+                $finalizedScopes
            );

            $response = new RedirectResponse();
@@ -193,11 +211,11 @@ class ImplicitGrant extends AbstractAuthorizeGrant
                    $finalRedirectUri,
                    [
                        'access_token' => (string) $accessToken->convertToJWT($this->privateKey),
-                        'token_type'   => 'bearer',
-                        'expires_in'   => $accessToken->getExpiryDateTime()->getTimestamp() - (new \DateTime())->getTimestamp(),
+                        'token_type'   => 'Bearer',
+                        'expires_in'   => $accessToken->getExpiryDateTime()->getTimestamp() - (new DateTime())->getTimestamp(),
                        'state'        => $authorizationRequest->getState(),
                    ],
-                    '#'
+                    $this->queryDelimiter
                )
            );

--- a/src/Grant/PasswordGrant.php
+++ b/src/Grant/PasswordGrant.php
@@ -8,8 +8,10 @@
 *
 * @link        https://github.com/thephpleague/oauth2-server
 */
+
 namespace League\OAuth2\Server\Grant;

+use DateInterval;
 use League\OAuth2\Server\Entities\ClientEntityInterface;
 use League\OAuth2\Server\Entities\UserEntityInterface;
 use League\OAuth2\Server\Exception\OAuthServerException;
@@ -25,8 +27,8 @@ use Psr\Http\Message\ServerRequestInterface;
 class PasswordGrant extends AbstractGrant
 {
    /**
-     * @param \League\OAuth2\Server\Repositories\UserRepositoryInterface         $userRepository
-     * @param \League\OAuth2\Server\Repositories\RefreshTokenRepositoryInterface $refreshTokenRepository
+     * @param UserRepositoryInterface         $userRepository
+     * @param RefreshTokenRepositoryInterface $refreshTokenRepository
     */
    public function __construct(
        UserRepositoryInterface $userRepository,
@@ -35,7 +37,7 @@ class PasswordGrant extends AbstractGrant
        $this->setUserRepository($userRepository);
        $this->setRefreshTokenRepository($refreshTokenRepository);

-        $this->refreshTokenTTL = new \DateInterval('P1M');
+        $this->refreshTokenTTL = new DateInterval('P1M');
    }

    /**
@@ -44,20 +46,24 @@ class PasswordGrant extends AbstractGrant
    public function respondToAccessTokenRequest(
        ServerRequestInterface $request,
        ResponseTypeInterface $responseType,
-        \DateInterval $accessTokenTTL
+        DateInterval $accessTokenTTL
    ) {
        // Validate request
        $client = $this->validateClient($request);
-        $scopes = $this->validateScopes($this->getRequestParameter('scope', $request));
+        $scopes = $this->validateScopes($this->getRequestParameter('scope', $request, $this->defaultScope));
        $user = $this->validateUser($request, $client);

        // Finalize the requested scopes
-        $scopes = $this->scopeRepository->finalizeScopes($scopes, $this->getIdentifier(), $client, $user->getIdentifier());
+        $finalizedScopes = $this->scopeRepository->finalizeScopes($scopes, $this->getIdentifier(), $client, $user->getIdentifier());

        // Issue and persist new tokens
-        $accessToken = $this->issueAccessToken($accessTokenTTL, $client, $user->getIdentifier(), $scopes);
+        $accessToken = $this->issueAccessToken($accessTokenTTL, $client, $user->getIdentifier(), $finalizedScopes);
        $refreshToken = $this->issueRefreshToken($accessToken);

+        // Send events to emitter
+        $this->getEmitter()->emit(new RequestEvent(RequestEvent::ACCESS_TOKEN_ISSUED, $request));
+        $this->getEmitter()->emit(new RequestEvent(RequestEvent::REFRESH_TOKEN_ISSUED, $request));
+
        // Inject tokens into response
        $responseType->setAccessToken($accessToken);
        $responseType->setRefreshToken($refreshToken);
@@ -66,12 +72,12 @@ class PasswordGrant extends AbstractGrant
    }

    /**
-     * @param \Psr\Http\Message\ServerRequestInterface             $request
-     * @param \League\OAuth2\Server\Entities\ClientEntityInterface $client
+     * @param ServerRequestInterface $request
+     * @param ClientEntityInterface  $client
     *
-     * @throws \League\OAuth2\Server\Exception\OAuthServerException
+     * @throws OAuthServerException
     *
-     * @return \League\OAuth2\Server\Entities\UserEntityInterface
+     * @return UserEntityInterface
     */
    protected function validateUser(ServerRequestInterface $request, ClientEntityInterface $client)
    {
@@ -91,7 +97,7 @@ class PasswordGrant extends AbstractGrant
            $this->getIdentifier(),
            $client
        );
-        if (!$user instanceof UserEntityInterface) {
+        if ($user instanceof UserEntityInterface === false) {
            $this->getEmitter()->emit(new RequestEvent(RequestEvent::USER_AUTHENTICATION_FAILED, $request));

            throw OAuthServerException::invalidCredentials();
--- a/src/Grant/RefreshTokenGrant.php
+++ b/src/Grant/RefreshTokenGrant.php
@@ -8,9 +8,11 @@
 *
 * @link        https://github.com/thephpleague/oauth2-server
 */
+
 namespace League\OAuth2\Server\Grant;

-use League\OAuth2\Server\Entities\ScopeEntityInterface;
+use DateInterval;
+use Exception;
 use League\OAuth2\Server\Exception\OAuthServerException;
 use League\OAuth2\Server\Repositories\RefreshTokenRepositoryInterface;
 use League\OAuth2\Server\RequestEvent;
@@ -23,13 +25,13 @@ use Psr\Http\Message\ServerRequestInterface;
 class RefreshTokenGrant extends AbstractGrant
 {
    /**
-     * @param \League\OAuth2\Server\Repositories\RefreshTokenRepositoryInterface $refreshTokenRepository
+     * @param RefreshTokenRepositoryInterface $refreshTokenRepository
     */
    public function __construct(RefreshTokenRepositoryInterface $refreshTokenRepository)
    {
        $this->setRefreshTokenRepository($refreshTokenRepository);

-        $this->refreshTokenTTL = new \DateInterval('P1M');
+        $this->refreshTokenTTL = new DateInterval('P1M');
    }

    /**
@@ -38,33 +40,22 @@ class RefreshTokenGrant extends AbstractGrant
    public function respondToAccessTokenRequest(
        ServerRequestInterface $request,
        ResponseTypeInterface $responseType,
-        \DateInterval $accessTokenTTL
+        DateInterval $accessTokenTTL
    ) {
        // Validate request
        $client = $this->validateClient($request);
        $oldRefreshToken = $this->validateOldRefreshToken($request, $client->getIdentifier());
-        $scopes = $this->validateScopes($this->getRequestParameter('scope', $request));
+        $scopes = $this->validateScopes($this->getRequestParameter(
+            'scope',
+            $request,
+            implode(self::SCOPE_DELIMITER_STRING, $oldRefreshToken['scopes']))
+        );

-        // If no new scopes are requested then give the access token the original session scopes
-        if (count($scopes) === 0) {
-            $scopes = array_map(function ($scopeId) use ($client) {
-                $scope = $this->scopeRepository->getScopeEntityByIdentifier($scopeId);
-
-                if (!$scope instanceof ScopeEntityInterface) {
-                    // @codeCoverageIgnoreStart
-                    throw OAuthServerException::invalidScope($scopeId);
-                    // @codeCoverageIgnoreEnd
-                }
-
-                return $scope;
-            }, $oldRefreshToken['scopes']);
-        } else {
-            // The OAuth spec says that a refreshed access token can have the original scopes or fewer so ensure
-            // the request doesn't include any new scopes
-            foreach ($scopes as $scope) {
-                if (in_array($scope->getIdentifier(), $oldRefreshToken['scopes']) === false) {
-                    throw OAuthServerException::invalidScope($scope->getIdentifier());
-                }
+        // The OAuth spec says that a refreshed access token can have the original scopes or fewer so ensure
+        // the request doesn't include any new scopes
+        foreach ($scopes as $scope) {
+            if (in_array($scope->getIdentifier(), $oldRefreshToken['scopes'], true) === false) {
+                throw OAuthServerException::invalidScope($scope->getIdentifier());
            }
        }

@@ -76,6 +67,10 @@ class RefreshTokenGrant extends AbstractGrant
        $accessToken = $this->issueAccessToken($accessTokenTTL, $client, $oldRefreshToken['user_id'], $scopes);
        $refreshToken = $this->issueRefreshToken($accessToken);

+        // Send events to emitter
+        $this->getEmitter()->emit(new RequestEvent(RequestEvent::ACCESS_TOKEN_ISSUED, $request));
+        $this->getEmitter()->emit(new RequestEvent(RequestEvent::REFRESH_TOKEN_ISSUED, $request));
+
        // Inject tokens into response
        $responseType->setAccessToken($accessToken);
        $responseType->setRefreshToken($refreshToken);
@@ -84,10 +79,10 @@ class RefreshTokenGrant extends AbstractGrant
    }

    /**
-     * @param \Psr\Http\Message\ServerRequestInterface $request
-     * @param string                                   $clientId
+     * @param ServerRequestInterface $request
+     * @param string                 $clientId
     *
-     * @throws \League\OAuth2\Server\Exception\OAuthServerException
+     * @throws OAuthServerException
     *
     * @return array
     */
@@ -101,8 +96,8 @@ class RefreshTokenGrant extends AbstractGrant
        // Validate refresh token
        try {
            $refreshToken = $this->decrypt($encryptedRefreshToken);
-        } catch (\LogicException $e) {
-            throw OAuthServerException::invalidRefreshToken('Cannot decrypt the refresh token');
+        } catch (Exception $e) {
+            throw OAuthServerException::invalidRefreshToken('Cannot decrypt the refresh token', $e);
        }

        $refreshTokenData = json_decode($refreshToken, true);
--- a/src/Middleware/AuthorizationServerMiddleware.php
+++ b/src/Middleware/AuthorizationServerMiddleware.php
@@ -9,6 +9,7 @@

 namespace League\OAuth2\Server\Middleware;

+use Exception;
 use League\OAuth2\Server\AuthorizationServer;
 use League\OAuth2\Server\Exception\OAuthServerException;
 use Psr\Http\Message\ResponseInterface;
@@ -17,14 +18,12 @@ use Psr\Http\Message\ServerRequestInterface;
 class AuthorizationServerMiddleware
 {
    /**
-     * @var \League\OAuth2\Server\AuthorizationServer
+     * @var AuthorizationServer
     */
    private $server;

    /**
-     * AuthorizationServerMiddleware constructor.
-     *
-     * @param \League\OAuth2\Server\AuthorizationServer $server
+     * @param AuthorizationServer $server
     */
    public function __construct(AuthorizationServer $server)
    {
@@ -32,11 +31,11 @@ class AuthorizationServerMiddleware
    }

    /**
-     * @param \Psr\Http\Message\ServerRequestInterface $request
-     * @param \Psr\Http\Message\ResponseInterface      $response
-     * @param callable                                 $next
+     * @param ServerRequestInterface $request
+     * @param ResponseInterface      $response
+     * @param callable               $next
     *
-     * @return \Psr\Http\Message\ResponseInterface
+     * @return ResponseInterface
     */
    public function __invoke(ServerRequestInterface $request, ResponseInterface $response, callable $next)
    {
@@ -45,7 +44,7 @@ class AuthorizationServerMiddleware
        } catch (OAuthServerException $exception) {
            return $exception->generateHttpResponse($response);
            // @codeCoverageIgnoreStart
-        } catch (\Exception $exception) {
+        } catch (Exception $exception) {
            return (new OAuthServerException($exception->getMessage(), 0, 'unknown_error', 500))
                ->generateHttpResponse($response);
            // @codeCoverageIgnoreEnd
--- a/src/Middleware/ResourceServerMiddleware.php
+++ b/src/Middleware/ResourceServerMiddleware.php
@@ -9,6 +9,7 @@

 namespace League\OAuth2\Server\Middleware;

+use Exception;
 use League\OAuth2\Server\Exception\OAuthServerException;
 use League\OAuth2\Server\ResourceServer;
 use Psr\Http\Message\ResponseInterface;
@@ -17,14 +18,12 @@ use Psr\Http\Message\ServerRequestInterface;
 class ResourceServerMiddleware
 {
    /**
-     * @var \League\OAuth2\Server\ResourceServer
+     * @var ResourceServer
     */
    private $server;

    /**
-     * ResourceServerMiddleware constructor.
-     *
-     * @param \League\OAuth2\Server\ResourceServer $server
+     * @param ResourceServer $server
     */
    public function __construct(ResourceServer $server)
    {
@@ -32,11 +31,11 @@ class ResourceServerMiddleware
    }

    /**
-     * @param \Psr\Http\Message\ServerRequestInterface $request
-     * @param \Psr\Http\Message\ResponseInterface      $response
-     * @param callable                                 $next
+     * @param ServerRequestInterface $request
+     * @param ResponseInterface      $response
+     * @param callable               $next
     *
-     * @return \Psr\Http\Message\ResponseInterface
+     * @return ResponseInterface
     */
    public function __invoke(ServerRequestInterface $request, ResponseInterface $response, callable $next)
    {
@@ -45,7 +44,7 @@ class ResourceServerMiddleware
        } catch (OAuthServerException $exception) {
            return $exception->generateHttpResponse($response);
            // @codeCoverageIgnoreStart
-        } catch (\Exception $exception) {
+        } catch (Exception $exception) {
            return (new OAuthServerException($exception->getMessage(), 0, 'unknown_error', 500))
                ->generateHttpResponse($response);
            // @codeCoverageIgnoreEnd
--- a/src/Repositories/AccessTokenRepositoryInterface.php
+++ b/src/Repositories/AccessTokenRepositoryInterface.php
@@ -11,6 +11,8 @@ namespace League\OAuth2\Server\Repositories;

 use League\OAuth2\Server\Entities\AccessTokenEntityInterface;
 use League\OAuth2\Server\Entities\ClientEntityInterface;
+use League\OAuth2\Server\Entities\ScopeEntityInterface;
+use League\OAuth2\Server\Exception\UniqueTokenIdentifierConstraintViolationException;

 /**
 * Access token interface.
@@ -20,9 +22,9 @@ interface AccessTokenRepositoryInterface extends RepositoryInterface
    /**
     * Create a new access token
     *
-     * @param \League\OAuth2\Server\Entities\ClientEntityInterface  $clientEntity
-     * @param \League\OAuth2\Server\Entities\ScopeEntityInterface[] $scopes
-     * @param mixed                                                 $userIdentifier
+     * @param ClientEntityInterface  $clientEntity
+     * @param ScopeEntityInterface[] $scopes
+     * @param mixed                  $userIdentifier
     *
     * @return AccessTokenEntityInterface
     */
@@ -31,7 +33,9 @@ interface AccessTokenRepositoryInterface extends RepositoryInterface
    /**
     * Persists a new access token to permanent storage.
     *
-     * @param \League\OAuth2\Server\Entities\AccessTokenEntityInterface $accessTokenEntity
+     * @param AccessTokenEntityInterface $accessTokenEntity
+     *
+     * @throws UniqueTokenIdentifierConstraintViolationException
     */
    public function persistNewAccessToken(AccessTokenEntityInterface $accessTokenEntity);

--- a/src/Repositories/AuthCodeRepositoryInterface.php
+++ b/src/Repositories/AuthCodeRepositoryInterface.php
@@ -6,9 +6,11 @@
 *
 * @link        https://github.com/thephpleague/oauth2-server
 */
+
 namespace League\OAuth2\Server\Repositories;

 use League\OAuth2\Server\Entities\AuthCodeEntityInterface;
+use League\OAuth2\Server\Exception\UniqueTokenIdentifierConstraintViolationException;

 /**
 * Auth code storage interface.
@@ -18,14 +20,16 @@ interface AuthCodeRepositoryInterface extends RepositoryInterface
    /**
     * Creates a new AuthCode
     *
-     * @return \League\OAuth2\Server\Entities\AuthCodeEntityInterface
+     * @return AuthCodeEntityInterface
     */
    public function getNewAuthCode();

    /**
     * Persists a new auth code to permanent storage.
     *
-     * @param \League\OAuth2\Server\Entities\AuthCodeEntityInterface $authCodeEntity
+     * @param AuthCodeEntityInterface $authCodeEntity
+     *
+     * @throws UniqueTokenIdentifierConstraintViolationException
     */
    public function persistNewAuthCode(AuthCodeEntityInterface $authCodeEntity);

--- a/src/Repositories/ClientRepositoryInterface.php
+++ b/src/Repositories/ClientRepositoryInterface.php
@@ -6,8 +6,11 @@
 *
 * @link        https://github.com/thephpleague/oauth2-server
 */
+
 namespace League\OAuth2\Server\Repositories;

+use League\OAuth2\Server\Entities\ClientEntityInterface;
+
 /**
 * Client storage interface.
 */
@@ -17,12 +20,12 @@ interface ClientRepositoryInterface extends RepositoryInterface
     * Get a client.
     *
     * @param string      $clientIdentifier   The client's identifier
-     * @param string      $grantType          The grant type used
+     * @param null|string $grantType          The grant type used (if sent)
     * @param null|string $clientSecret       The client's secret (if sent)
-     * @param bool        $mustValidateSecret If true the client must attempt to validate the secret unless the client
+     * @param bool        $mustValidateSecret If true the client must attempt to validate the secret if the client
     *                                        is confidential
     *
-     * @return \League\OAuth2\Server\Entities\ClientEntityInterface
+     * @return ClientEntityInterface
     */
-    public function getClientEntity($clientIdentifier, $grantType, $clientSecret = null, $mustValidateSecret = true);
+    public function getClientEntity($clientIdentifier, $grantType = null, $clientSecret = null, $mustValidateSecret = true);
 }
--- a/src/Repositories/RefreshTokenRepositoryInterface.php
+++ b/src/Repositories/RefreshTokenRepositoryInterface.php
@@ -6,9 +6,11 @@
 *
 * @link        https://github.com/thephpleague/oauth2-server
 */
+
 namespace League\OAuth2\Server\Repositories;

 use League\OAuth2\Server\Entities\RefreshTokenEntityInterface;
+use League\OAuth2\Server\Exception\UniqueTokenIdentifierConstraintViolationException;

 /**
 * Refresh token interface.
@@ -25,7 +27,9 @@ interface RefreshTokenRepositoryInterface extends RepositoryInterface
    /**
     * Create a new refresh token_name.
     *
-     * @param \League\OAuth2\Server\Entities\RefreshTokenEntityInterface $refreshTokenEntity
+     * @param RefreshTokenEntityInterface $refreshTokenEntity
+     *
+     * @throws UniqueTokenIdentifierConstraintViolationException
     */
    public function persistNewRefreshToken(RefreshTokenEntityInterface $refreshTokenEntity);

--- a/src/Repositories/RepositoryInterface.php
+++ b/src/Repositories/RepositoryInterface.php
@@ -6,6 +6,7 @@
 *
 * @link        https://github.com/thephpleague/oauth2-server
 */
+
 namespace League\OAuth2\Server\Repositories;

 /**
--- a/src/Repositories/ScopeRepositoryInterface.php
+++ b/src/Repositories/ScopeRepositoryInterface.php
@@ -22,7 +22,7 @@ interface ScopeRepositoryInterface extends RepositoryInterface
     *
     * @param string $identifier The scope identifier
     *
-     * @return \League\OAuth2\Server\Entities\ScopeEntityInterface
+     * @return ScopeEntityInterface
     */
    public function getScopeEntityByIdentifier($identifier);

@@ -30,12 +30,12 @@ interface ScopeRepositoryInterface extends RepositoryInterface
     * Given a client, grant type and optional user identifier validate the set of scopes requested are valid and optionally
     * append additional scopes or remove requested scopes.
     *
-     * @param ScopeEntityInterface[]                               $scopes
-     * @param string                                               $grantType
-     * @param \League\OAuth2\Server\Entities\ClientEntityInterface $clientEntity
-     * @param null|string                                          $userIdentifier
+     * @param ScopeEntityInterface[] $scopes
+     * @param string                 $grantType
+     * @param ClientEntityInterface  $clientEntity
+     * @param null|string            $userIdentifier
     *
-     * @return \League\OAuth2\Server\Entities\ScopeEntityInterface[]
+     * @return ScopeEntityInterface[]
     */
    public function finalizeScopes(
        array $scopes,
--- a/src/Repositories/UserRepositoryInterface.php
+++ b/src/Repositories/UserRepositoryInterface.php
@@ -10,18 +10,19 @@
 namespace League\OAuth2\Server\Repositories;

 use League\OAuth2\Server\Entities\ClientEntityInterface;
+use League\OAuth2\Server\Entities\UserEntityInterface;

 interface UserRepositoryInterface extends RepositoryInterface
 {
    /**
     * Get a user entity.
     *
-     * @param string                                               $username
-     * @param string                                               $password
-     * @param string                                               $grantType    The grant type used
-     * @param \League\OAuth2\Server\Entities\ClientEntityInterface $clientEntity
+     * @param string                $username
+     * @param string                $password
+     * @param string                $grantType    The grant type used
+     * @param ClientEntityInterface $clientEntity
     *
-     * @return \League\OAuth2\Server\Entities\UserEntityInterface
+     * @return UserEntityInterface
     */
    public function getUserEntityByUserCredentials(
        $username,
--- a/src/RequestEvent.php
+++ b/src/RequestEvent.php
@@ -6,6 +6,7 @@
 *
 * @link        https://github.com/thephpleague/oauth2-server
 */
+
 namespace League\OAuth2\Server;

 use League\Event\Event;
@@ -17,16 +18,19 @@ class RequestEvent extends Event
    const USER_AUTHENTICATION_FAILED = 'user.authentication.failed';
    const REFRESH_TOKEN_CLIENT_FAILED = 'refresh_token.client.failed';

+    const REFRESH_TOKEN_ISSUED = 'refresh_token.issued';
+    const ACCESS_TOKEN_ISSUED = 'access_token.issued';
+
    /**
-     * @var \Psr\Http\Message\ServerRequestInterface
+     * @var ServerRequestInterface
     */
    private $request;

    /**
     * RequestEvent constructor.
     *
-     * @param string                                   $name
-     * @param \Psr\Http\Message\ServerRequestInterface $request
+     * @param string                 $name
+     * @param ServerRequestInterface $request
     */
    public function __construct($name, ServerRequestInterface $request)
    {
--- a/src/RequestTypes/AuthorizationRequest.php
+++ b/src/RequestTypes/AuthorizationRequest.php
@@ -53,25 +53,27 @@ class AuthorizationRequest
    /**
     * The redirect URI used in the request
     *
-     * @var string
+     * @var string|null
     */
    protected $redirectUri;

    /**
     * The state parameter on the authorization request
     *
-     * @var string
+     * @var string|null
     */
    protected $state;

    /**
     * The code challenge (if provided)
+     *
     * @var string
     */
    protected $codeChallenge;

    /**
     * The code challenge method (if provided)
+     *
     * @var string
     */
    protected $codeChallengeMethod;
@@ -125,7 +127,7 @@ class AuthorizationRequest
    }

    /**
-     * @return \League\OAuth2\Server\Entities\ScopeEntityInterface[]
+     * @return ScopeEntityInterface[]
     */
    public function getScopes()
    {
@@ -133,9 +135,9 @@ class AuthorizationRequest
    }

    /**
-     * @param \League\OAuth2\Server\Entities\ScopeEntityInterface[] $scopes
+     * @param ScopeEntityInterface[] $scopes
     */
-    public function setScopes($scopes)
+    public function setScopes(array $scopes)
    {
        $this->scopes = $scopes;
    }
@@ -157,7 +159,7 @@ class AuthorizationRequest
    }

    /**
-     * @return string
+     * @return string|null
     */
    public function getRedirectUri()
    {
@@ -165,7 +167,7 @@ class AuthorizationRequest
    }

    /**
-     * @param string $redirectUri
+     * @param string|null $redirectUri
     */
    public function setRedirectUri($redirectUri)
    {
@@ -173,7 +175,7 @@ class AuthorizationRequest
    }

    /**
-     * @return string
+     * @return string|null
     */
    public function getState()
    {
--- a/src/ResourceServer.php
+++ b/src/ResourceServer.php
@@ -6,34 +6,38 @@
 *
 * @link        https://github.com/thephpleague/oauth2-server
 */
+
 namespace League\OAuth2\Server;

 use League\OAuth2\Server\AuthorizationValidators\AuthorizationValidatorInterface;
 use League\OAuth2\Server\AuthorizationValidators\BearerTokenValidator;
+use League\OAuth2\Server\Exception\OAuthServerException;
 use League\OAuth2\Server\Repositories\AccessTokenRepositoryInterface;
 use Psr\Http\Message\ServerRequestInterface;

 class ResourceServer
 {
    /**
-     * @var \League\OAuth2\Server\Repositories\AccessTokenRepositoryInterface
+     * @var AccessTokenRepositoryInterface
     */
    private $accessTokenRepository;
+
    /**
-     * @var \League\OAuth2\Server\CryptKey|string
+     * @var CryptKey
     */
    private $publicKey;
+
    /**
-     * @var \League\OAuth2\Server\AuthorizationValidators\AuthorizationValidatorInterface|null
+     * @var null|AuthorizationValidatorInterface
     */
    private $authorizationValidator;

    /**
     * New server instance.
     *
-     * @param \League\OAuth2\Server\Repositories\AccessTokenRepositoryInterface                  $accessTokenRepository
-     * @param \League\OAuth2\Server\CryptKey|string                                              $publicKey
-     * @param null|\League\OAuth2\Server\AuthorizationValidators\AuthorizationValidatorInterface $authorizationValidator
+     * @param AccessTokenRepositoryInterface       $accessTokenRepository
+     * @param CryptKey|string                      $publicKey
+     * @param null|AuthorizationValidatorInterface $authorizationValidator
     */
    public function __construct(
        AccessTokenRepositoryInterface $accessTokenRepository,
@@ -42,7 +46,7 @@ class ResourceServer
    ) {
        $this->accessTokenRepository = $accessTokenRepository;

-        if (!$publicKey instanceof CryptKey) {
+        if ($publicKey instanceof CryptKey === false) {
            $publicKey = new CryptKey($publicKey);
        }
        $this->publicKey = $publicKey;
@@ -51,15 +55,17 @@ class ResourceServer
    }

    /**
-     * @return \League\OAuth2\Server\AuthorizationValidators\AuthorizationValidatorInterface
+     * @return AuthorizationValidatorInterface
     */
    protected function getAuthorizationValidator()
    {
-        if (!$this->authorizationValidator instanceof AuthorizationValidatorInterface) {
+        if ($this->authorizationValidator instanceof AuthorizationValidatorInterface === false) {
            $this->authorizationValidator = new BearerTokenValidator($this->accessTokenRepository);
        }

-        $this->authorizationValidator->setPublicKey($this->publicKey);
+        if ($this->authorizationValidator instanceof BearerTokenValidator === true) {
+            $this->authorizationValidator->setPublicKey($this->publicKey);
+        }

        return $this->authorizationValidator;
    }
@@ -67,11 +73,11 @@ class ResourceServer
    /**
     * Determine the access token validity.
     *
-     * @param \Psr\Http\Message\ServerRequestInterface $request
+     * @param ServerRequestInterface $request
     *
-     * @throws \League\OAuth2\Server\Exception\OAuthServerException
+     * @throws OAuthServerException
     *
-     * @return \Psr\Http\Message\ServerRequestInterface
+     * @return ServerRequestInterface
     */
    public function validateAuthenticatedRequest(ServerRequestInterface $request)
    {
--- a/src/ResponseTypes/AbstractResponseType.php
+++ b/src/ResponseTypes/AbstractResponseType.php
@@ -8,8 +8,10 @@
 *
 * @link        https://github.com/thephpleague/oauth2-server
 */
+
 namespace League\OAuth2\Server\ResponseTypes;

+use League\OAuth2\Server\CryptKey;
 use League\OAuth2\Server\CryptTrait;
 use League\OAuth2\Server\Entities\AccessTokenEntityInterface;
 use League\OAuth2\Server\Entities\RefreshTokenEntityInterface;
@@ -19,15 +21,20 @@ abstract class AbstractResponseType implements ResponseTypeInterface
    use CryptTrait;

    /**
-     * @var \League\OAuth2\Server\Entities\AccessTokenEntityInterface
+     * @var AccessTokenEntityInterface
     */
    protected $accessToken;

    /**
-     * @var \League\OAuth2\Server\Entities\RefreshTokenEntityInterface
+     * @var RefreshTokenEntityInterface
     */
    protected $refreshToken;

+    /**
+     * @var CryptKey
+     */
+    protected $privateKey;
+
    /**
     * {@inheritdoc}
     */
@@ -43,4 +50,14 @@ abstract class AbstractResponseType implements ResponseTypeInterface
    {
        $this->refreshToken = $refreshToken;
    }
+
+    /**
+     * Set the private key
+     *
+     * @param CryptKey $key
+     */
+    public function setPrivateKey(CryptKey $key)
+    {
+        $this->privateKey = $key;
+    }
 }
--- a/src/ResponseTypes/BearerTokenResponse.php
+++ b/src/ResponseTypes/BearerTokenResponse.php
@@ -1,6 +1,6 @@
 <?php
 /**
- * OAuth 2.0 Bearer Token Type.
+ * OAuth 2.0 Bearer Token Response.
 *
 * @author      Alex Bilbie <hello@alexbilbie.com>
 * @copyright   Copyright (c) Alex Bilbie
@@ -8,8 +8,11 @@
 *
 * @link        https://github.com/thephpleague/oauth2-server
 */
+
 namespace League\OAuth2\Server\ResponseTypes;

+use DateTime;
+use League\OAuth2\Server\Entities\AccessTokenEntityInterface;
 use League\OAuth2\Server\Entities\RefreshTokenEntityInterface;
 use Psr\Http\Message\ResponseInterface;

@@ -26,7 +29,7 @@ class BearerTokenResponse extends AbstractResponseType

        $responseParams = [
            'token_type'   => 'Bearer',
-            'expires_in'   => $expireDateTime - (new \DateTime())->getTimestamp(),
+            'expires_in'   => $expireDateTime - (new DateTime())->getTimestamp(),
            'access_token' => (string) $jwtAccessToken,
        ];

@@ -47,6 +50,8 @@ class BearerTokenResponse extends AbstractResponseType
            $responseParams['refresh_token'] = $refreshToken;
        }

+        $responseParams = array_merge($this->getExtraParams($this->accessToken), $responseParams);
+
        $response = $response
            ->withStatus(200)
            ->withHeader('pragma', 'no-cache')
@@ -57,4 +62,18 @@ class BearerTokenResponse extends AbstractResponseType

        return $response;
    }
+
+    /**
+     * Add custom fields to your Bearer Token response here, then override
+     * AuthorizationServer::getResponseType() to pull in your version of
+     * this class rather than the default.
+     *
+     * @param AccessTokenEntityInterface $accessToken
+     *
+     * @return array
+     */
+    protected function getExtraParams(AccessTokenEntityInterface $accessToken)
+    {
+        return [];
+    }
 }
--- a/src/ResponseTypes/RedirectResponse.php
+++ b/src/ResponseTypes/RedirectResponse.php
@@ -1,4 +1,13 @@
 <?php
+/**
+ * OAuth 2.0 Redirect Response.
+ *
+ * @author      Alex Bilbie <hello@alexbilbie.com>
+ * @copyright   Copyright (c) Alex Bilbie
+ * @license     http://mit-license.org/
+ *
+ * @link        https://github.com/thephpleague/oauth2-server
+ */

 namespace League\OAuth2\Server\ResponseTypes;

--- a/src/ResponseTypes/ResponseTypeInterface.php
+++ b/src/ResponseTypes/ResponseTypeInterface.php
@@ -8,8 +8,10 @@
 *
 * @link        https://github.com/thephpleague/oauth2-server
 */
+
 namespace League\OAuth2\Server\ResponseTypes;

+use Defuse\Crypto\Key;
 use League\OAuth2\Server\Entities\AccessTokenEntityInterface;
 use League\OAuth2\Server\Entities\RefreshTokenEntityInterface;
 use Psr\Http\Message\ResponseInterface;
@@ -17,12 +19,12 @@ use Psr\Http\Message\ResponseInterface;
 interface ResponseTypeInterface
 {
    /**
-     * @param \League\OAuth2\Server\Entities\AccessTokenEntityInterface $accessToken
+     * @param AccessTokenEntityInterface $accessToken
     */
    public function setAccessToken(AccessTokenEntityInterface $accessToken);

    /**
-     * @param \League\OAuth2\Server\Entities\RefreshTokenEntityInterface $refreshToken
+     * @param RefreshTokenEntityInterface $refreshToken
     */
    public function setRefreshToken(RefreshTokenEntityInterface $refreshToken);

@@ -32,4 +34,11 @@ interface ResponseTypeInterface
     * @return ResponseInterface
     */
    public function generateHttpResponse(ResponseInterface $response);
+
+    /**
+     * Set the encryption key
+     *
+     * @param string|Key|null $key
+     */
+    public function setEncryptionKey($key = null);
 }
--- a/tests/AuthorizationServerTest.php
+++ b/tests/AuthorizationServerTest.php
@@ -17,23 +17,35 @@ use League\OAuth2\Server\ResponseTypes\BearerTokenResponse;
 use LeagueTests\Stubs\AccessTokenEntity;
 use LeagueTests\Stubs\AuthCodeEntity;
 use LeagueTests\Stubs\ClientEntity;
+use LeagueTests\Stubs\ScopeEntity;
 use LeagueTests\Stubs\StubResponseType;
 use LeagueTests\Stubs\UserEntity;
+use PHPUnit\Framework\TestCase;
 use Psr\Http\Message\ResponseInterface;
 use Zend\Diactoros\Response;
 use Zend\Diactoros\ServerRequest;
 use Zend\Diactoros\ServerRequestFactory;

-class AuthorizationServerTest extends \PHPUnit_Framework_TestCase
+class AuthorizationServerTest extends TestCase
 {
+    const DEFAULT_SCOPE = 'basic';
+
+    public function setUp()
+    {
+        // Make sure the keys have the correct permissions.
+        chmod(__DIR__ . '/Stubs/private.key', 0600);
+        chmod(__DIR__ . '/Stubs/public.key', 0600);
+        chmod(__DIR__ . '/Stubs/private.key.crlf', 0600);
+    }
+
    public function testRespondToRequestInvalidGrantType()
    {
        $server = new AuthorizationServer(
-            $this->getMock(ClientRepositoryInterface::class),
-            $this->getMock(AccessTokenRepositoryInterface::class),
-            $this->getMock(ScopeRepositoryInterface::class),
+            $this->getMockBuilder(ClientRepositoryInterface::class)->getMock(),
+            $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock(),
+            $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock(),
            'file://' . __DIR__ . '/Stubs/private.key',
-            'file://' . __DIR__ . '/Stubs/public.key',
+            base64_encode(random_bytes(36)),
            new StubResponseType()
        );

@@ -49,13 +61,15 @@ class AuthorizationServerTest extends \PHPUnit_Framework_TestCase

    public function testRespondToRequest()
    {
-        $clientRepository = $this->getMock(ClientRepositoryInterface::class);
+        $clientRepository = $this->getMockBuilder(ClientRepositoryInterface::class)->getMock();
        $clientRepository->method('getClientEntity')->willReturn(new ClientEntity());

+        $scope = new ScopeEntity();
        $scopeRepositoryMock = $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock();
+        $scopeRepositoryMock->method('getScopeEntityByIdentifier')->willReturn($scope);
        $scopeRepositoryMock->method('finalizeScopes')->willReturnArgument(0);

-        $accessTokenRepositoryMock = $this->getMock(AccessTokenRepositoryInterface::class);
+        $accessTokenRepositoryMock = $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock();
        $accessTokenRepositoryMock->method('getNewToken')->willReturn(new AccessTokenEntity());

        $server = new AuthorizationServer(
@@ -63,10 +77,11 @@ class AuthorizationServerTest extends \PHPUnit_Framework_TestCase
            $accessTokenRepositoryMock,
            $scopeRepositoryMock,
            'file://' . __DIR__ . '/Stubs/private.key',
-            'file://' . __DIR__ . '/Stubs/public.key',
+            base64_encode(random_bytes(36)),
            new StubResponseType()
        );

+        $server->setDefaultScope(self::DEFAULT_SCOPE);
        $server->enableGrantType(new ClientCredentialsGrant(), new \DateInterval('PT1M'));

        $_POST['grant_type'] = 'client_credentials';
@@ -78,12 +93,12 @@ class AuthorizationServerTest extends \PHPUnit_Framework_TestCase

    public function testGetResponseType()
    {
-        $clientRepository = $this->getMock(ClientRepositoryInterface::class);
+        $clientRepository = $this->getMockBuilder(ClientRepositoryInterface::class)->getMock();

        $server = new AuthorizationServer(
            $clientRepository,
-            $this->getMock(AccessTokenRepositoryInterface::class),
-            $this->getMock(ScopeRepositoryInterface::class),
+            $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock(),
+            $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock(),
            'file://' . __DIR__ . '/Stubs/private.key',
            'file://' . __DIR__ . '/Stubs/public.key'
        );
@@ -92,17 +107,106 @@ class AuthorizationServerTest extends \PHPUnit_Framework_TestCase
        $method = $abstractGrantReflection->getMethod('getResponseType');
        $method->setAccessible(true);

-        $this->assertTrue($method->invoke($server) instanceof BearerTokenResponse);
+        $this->assertInstanceOf(BearerTokenResponse::class, $method->invoke($server));
+    }
+
+    public function testGetResponseTypeExtended()
+    {
+        $clientRepository = $this->getMockBuilder(ClientRepositoryInterface::class)->getMock();
+        $privateKey = 'file://' . __DIR__ . '/Stubs/private.key';
+        $encryptionKey = 'file://' . __DIR__ . '/Stubs/public.key';
+
+        $server = new class($clientRepository, $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock(), $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock(), $privateKey, $encryptionKey) extends AuthorizationServer {
+            protected function getResponseType()
+            {
+                $this->responseType = new class extends BearerTokenResponse {
+                    /* @return null|CryptKey */
+                    public function getPrivateKey()
+                    {
+                        return $this->privateKey;
+                    }
+
+                    public function getEncryptionKey()
+                    {
+                        return $this->encryptionKey;
+                    }
+                };
+
+                return parent::getResponseType();
+            }
+        };
+
+        $abstractGrantReflection = new \ReflectionClass($server);
+        $method = $abstractGrantReflection->getMethod('getResponseType');
+        $method->setAccessible(true);
+        $responseType = $method->invoke($server);
+
+        $this->assertInstanceOf(BearerTokenResponse::class, $responseType);
+        // generated instances should have keys setup
+        $this->assertSame($privateKey, $responseType->getPrivateKey()->getKeyPath());
+        $this->assertSame($encryptionKey, $responseType->getEncryptionKey());
+    }
+
+    public function testMultipleRequestsGetDifferentResponseTypeInstances()
+    {
+        $privateKey = 'file://' . __DIR__ . '/Stubs/private.key';
+        $encryptionKey = 'file://' . __DIR__ . '/Stubs/public.key';
+
+        $responseTypePrototype = new class extends BearerTokenResponse {
+            /* @return null|CryptKey */
+            public function getPrivateKey()
+            {
+                return $this->privateKey;
+            }
+
+            public function getEncryptionKey()
+            {
+                return $this->encryptionKey;
+            }
+        };
+
+        $clientRepository = $this->getMockBuilder(ClientRepositoryInterface::class)->getMock();
+
+        $server = new AuthorizationServer(
+            $clientRepository,
+            $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock(),
+            $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock(),
+            $privateKey,
+            $encryptionKey,
+            $responseTypePrototype
+        );
+
+        $abstractGrantReflection = new \ReflectionClass($server);
+        $method = $abstractGrantReflection->getMethod('getResponseType');
+        $method->setAccessible(true);
+
+        $responseTypeA = $method->invoke($server);
+        $responseTypeB = $method->invoke($server);
+
+        // prototype should not get changed
+        $this->assertNull($responseTypePrototype->getPrivateKey());
+        $this->assertNull($responseTypePrototype->getEncryptionKey());
+
+        // generated instances should have keys setup
+        $this->assertSame($privateKey, $responseTypeA->getPrivateKey()->getKeyPath());
+        $this->assertSame($encryptionKey, $responseTypeA->getEncryptionKey());
+
+        // all instances should be different but based on the same prototype
+        $this->assertSame(get_class($responseTypePrototype), get_class($responseTypeA));
+        $this->assertSame(get_class($responseTypePrototype), get_class($responseTypeB));
+        $this->assertNotSame($responseTypePrototype, $responseTypeA);
+        $this->assertNotSame($responseTypePrototype, $responseTypeB);
+        $this->assertNotSame($responseTypeA, $responseTypeB);
    }

    public function testCompleteAuthorizationRequest()
    {
-        $clientRepository = $this->getMock(ClientRepositoryInterface::class);
+        $clientRepository = $this->getMockBuilder(ClientRepositoryInterface::class)->getMock();

        $server = new AuthorizationServer(
            $clientRepository,
-            $this->getMock(AccessTokenRepositoryInterface::class),
-            $this->getMock(ScopeRepositoryInterface::class),
+            $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock(),
+            $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock(),
            'file://' . __DIR__ . '/Stubs/private.key',
            'file://' . __DIR__ . '/Stubs/public.key'
        );
@@ -112,13 +216,10 @@ class AuthorizationServerTest extends \PHPUnit_Framework_TestCase

        $grant = new AuthCodeGrant(
            $authCodeRepository,
-            $this->getMock(RefreshTokenRepositoryInterface::class),
+            $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock(),
            new \DateInterval('PT10M')
        );

-        $grant->setPrivateKey(new CryptKey('file://' . __DIR__ . '/Stubs/private.key'));
-        $grant->setPublicKey(new CryptKey('file://' . __DIR__ . '/Stubs/public.key'));
-
        $server->enableGrantType($grant);

        $authRequest = new AuthorizationRequest();
@@ -127,28 +228,75 @@ class AuthorizationServerTest extends \PHPUnit_Framework_TestCase
        $authRequest->setGrantTypeId('authorization_code');
        $authRequest->setUser(new UserEntity());

-        $this->assertTrue(
-            $server->completeAuthorizationRequest($authRequest, new Response) instanceof ResponseInterface
+        $this->assertInstanceOf(
+            ResponseInterface::class,
+            $server->completeAuthorizationRequest($authRequest, new Response)
        );
    }

    public function testValidateAuthorizationRequest()
    {
        $client = new ClientEntity();
+        $client->setRedirectUri('http://foo/bar');
        $clientRepositoryMock = $this->getMockBuilder(ClientRepositoryInterface::class)->getMock();
        $clientRepositoryMock->method('getClientEntity')->willReturn($client);

+        $scope = new ScopeEntity();
+        $scopeRepositoryMock = $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock();
+        $scopeRepositoryMock->method('getScopeEntityByIdentifier')->willReturn($scope);
+
        $grant = new AuthCodeGrant(
-            $this->getMock(AuthCodeRepositoryInterface::class),
-            $this->getMock(RefreshTokenRepositoryInterface::class),
+            $this->getMockBuilder(AuthCodeRepositoryInterface::class)->getMock(),
+            $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock(),
            new \DateInterval('PT10M')
        );
        $grant->setClientRepository($clientRepositoryMock);

        $server = new AuthorizationServer(
            $clientRepositoryMock,
-            $this->getMock(AccessTokenRepositoryInterface::class),
-            $this->getMock(ScopeRepositoryInterface::class),
+            $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock(),
+            $scopeRepositoryMock,
+            'file://' . __DIR__ . '/Stubs/private.key',
+            'file://' . __DIR__ . '/Stubs/public.key'
+        );
+
+        $server->setDefaultScope(self::DEFAULT_SCOPE);
+        $server->enableGrantType($grant);
+
+        $request = new ServerRequest(
+            [],
+            [],
+            null,
+            null,
+            'php://input',
+            $headers = [],
+            $cookies = [],
+            $queryParams = [
+                'response_type' => 'code',
+                'client_id'     => 'foo',
+            ]
+        );
+
+        $this->assertInstanceOf(AuthorizationRequest::class, $server->validateAuthorizationRequest($request));
+    }
+
+    public function testValidateAuthorizationRequestWithMissingRedirectUri()
+    {
+        $client = new ClientEntity();
+        $clientRepositoryMock = $this->getMockBuilder(ClientRepositoryInterface::class)->getMock();
+        $clientRepositoryMock->method('getClientEntity')->willReturn($client);
+
+        $grant = new AuthCodeGrant(
+            $this->getMockBuilder(AuthCodeRepositoryInterface::class)->getMock(),
+            $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock(),
+            new \DateInterval('PT10M')
+        );
+        $grant->setClientRepository($clientRepositoryMock);
+
+        $server = new AuthorizationServer(
+            $clientRepositoryMock,
+            $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock(),
+            $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock(),
            'file://' . __DIR__ . '/Stubs/private.key',
            'file://' . __DIR__ . '/Stubs/public.key'
        );
@@ -168,7 +316,12 @@ class AuthorizationServerTest extends \PHPUnit_Framework_TestCase
            ]
        );

-        $this->assertTrue($server->validateAuthorizationRequest($request) instanceof AuthorizationRequest);
+        try {
+            $server->validateAuthorizationRequest($request);
+        } catch (OAuthServerException $e) {
+            $this->assertEquals('invalid_client', $e->getErrorType());
+            $this->assertEquals(401, $e->getHttpStatusCode());
+        }
    }

    /**
@@ -178,9 +331,9 @@ class AuthorizationServerTest extends \PHPUnit_Framework_TestCase
    public function testValidateAuthorizationRequestUnregistered()
    {
        $server = new AuthorizationServer(
-            $this->getMock(ClientRepositoryInterface::class),
-            $this->getMock(AccessTokenRepositoryInterface::class),
-            $this->getMock(ScopeRepositoryInterface::class),
+            $this->getMockBuilder(ClientRepositoryInterface::class)->getMock(),
+            $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock(),
+            $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock(),
            'file://' . __DIR__ . '/Stubs/private.key',
            'file://' . __DIR__ . '/Stubs/public.key'
        );
--- a/tests/AuthorizationValidators/BearerTokenValidatorTest.php
+++ b/tests/AuthorizationValidators/BearerTokenValidatorTest.php
@@ -0,0 +1,40 @@
+<?php
+
+namespace LeagueTests\AuthorizationValidators;
+
+use Lcobucci\JWT\Builder;
+use League\OAuth2\Server\AuthorizationValidators\BearerTokenValidator;
+use League\OAuth2\Server\CryptKey;
+use League\OAuth2\Server\Repositories\AccessTokenRepositoryInterface;
+use PHPUnit\Framework\TestCase;
+use Zend\Diactoros\ServerRequest;
+
+class BearerTokenValidatorTest extends TestCase
+{
+    /**
+     * @expectedException League\OAuth2\Server\Exception\OAuthServerException
+     * @expectedExceptionCode 9
+     */
+    public function testThrowExceptionWhenAccessTokenIsNotSigned()
+    {
+        $accessTokenRepositoryMock = $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock();
+
+        $bearerTokenValidator = new BearerTokenValidator($accessTokenRepositoryMock);
+        $bearerTokenValidator->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));
+
+        $unsignedJwt = (new Builder())
+            ->setAudience('client-id')
+            ->setId('token-id', true)
+            ->setIssuedAt(time())
+            ->setNotBefore(time())
+            ->setExpiration(time())
+            ->setSubject('user-id')
+            ->set('scopes', 'scope1 scope2 scope3 scope4')
+            ->getToken();
+
+        $request = new ServerRequest();
+        $request = $request->withHeader('authorization', sprintf('Bearer %s', $unsignedJwt));
+
+        $bearerTokenValidator->validateAuthorization($request);
+    }
+}
--- a/tests/CryptTraitTest.php
+++ b/tests/CryptTraitTest.php
@@ -1,55 +0,0 @@
-<?php
-
-namespace LeagueTests\Utils;
-
-use League\OAuth2\Server\CryptKey;
-use LeagueTests\Stubs\CryptTraitStub;
-
-class CryptTraitTest extends \PHPUnit_Framework_TestCase
-{
-    /**
-     * CryptTrait stub
-     */
-    protected $cryptStub;
-
-    public function setUp()
-    {
-        $this->cryptStub = new CryptTraitStub;
-    }
-
-    public function testEncryptDecrypt()
-    {
-        $payload = 'alex loves whisky';
-        $encrypted = $this->cryptStub->doEncrypt($payload);
-        $plainText = $this->cryptStub->doDecrypt($encrypted);
-
-        $this->assertNotEquals($payload, $encrypted);
-        $this->assertEquals($payload, $plainText);
-    }
-
-    /**
-     * @expectedException \LogicException
-     */
-    public function testBadPrivateKey()
-    {
-        $this->cryptStub->setPrivateKey(new CryptKey(__DIR__ . '/Stubs/public.key'));
-        $this->cryptStub->doEncrypt('');
-    }
-
-    /**
-     * @expectedException \LogicException
-     */
-    public function testBadPublicKey()
-    {
-        $this->cryptStub->setPublicKey(new CryptKey(__DIR__ . '/Stubs/private.key'));
-        $this->cryptStub->doDecrypt('');
-    }
-
-    /**
-     * @expectedException \LogicException
-     */
-    public function testNonExistentKey()
-    {
-        new CryptKey('foo/bar');
-    }
-}
--- a/tests/Exception/OAuthServerExceptionTest.php
+++ b/tests/Exception/OAuthServerExceptionTest.php
@@ -0,0 +1,39 @@
+<?php
+
+namespace LeagueTests\Exception;
+
+use Exception;
+use League\OAuth2\Server\Exception\OAuthServerException;
+use PHPUnit\Framework\TestCase;
+
+class OAuthServerExceptionTest extends TestCase
+{
+    public function testHasRedirect()
+    {
+        $exceptionWithRedirect = OAuthServerException::accessDenied('some hint', 'https://example.com/error');
+
+        $this->assertTrue($exceptionWithRedirect->hasRedirect());
+    }
+
+    public function testDoesNotHaveRedirect()
+    {
+        $exceptionWithoutRedirect = OAuthServerException::accessDenied('Some hint');
+
+        $this->assertFalse($exceptionWithoutRedirect->hasRedirect());
+    }
+
+    public function testHasPrevious()
+    {
+        $previous = new Exception('This is the previous');
+        $exceptionWithPrevious = OAuthServerException::accessDenied(null, null, $previous);
+
+        $this->assertSame('This is the previous', $exceptionWithPrevious->getPrevious()->getMessage());
+    }
+
+    public function testDoesNotHavePrevious()
+    {
+        $exceptionWithoutPrevious = OAuthServerException::accessDenied();
+
+        $this->assertNull($exceptionWithoutPrevious->getPrevious());
+    }
+}
--- a/tests/Grant/AbstractGrantTest.php
+++ b/tests/Grant/AbstractGrantTest.php
@@ -3,7 +3,6 @@
 namespace LeagueTests\Grant;

 use League\Event\Emitter;
-use League\OAuth2\Server\CryptKey;
 use League\OAuth2\Server\Entities\AccessTokenEntityInterface;
 use League\OAuth2\Server\Entities\AuthCodeEntityInterface;
 use League\OAuth2\Server\Entities\RefreshTokenEntityInterface;
@@ -19,16 +18,15 @@ use LeagueTests\Stubs\AuthCodeEntity;
 use LeagueTests\Stubs\ClientEntity;
 use LeagueTests\Stubs\RefreshTokenEntity;
 use LeagueTests\Stubs\ScopeEntity;
+use PHPUnit\Framework\TestCase;
 use Zend\Diactoros\ServerRequest;

-class AbstractGrantTest extends \PHPUnit_Framework_TestCase
+class AbstractGrantTest extends TestCase
 {
    public function testGetSet()
    {
        /** @var AbstractGrant $grantMock */
        $grantMock = $this->getMockForAbstractClass(AbstractGrant::class);
-        $grantMock->setPrivateKey(new CryptKey(__DIR__ . '/../Stubs/private.key'));
-        $grantMock->setPublicKey(new CryptKey(__DIR__ . '/../Stubs/public.key'));
        $grantMock->setEmitter(new Emitter());
    }

@@ -326,7 +324,7 @@ class AbstractGrantTest extends \PHPUnit_Framework_TestCase

    public function testIssueRefreshToken()
    {
-        $refreshTokenRepoMock = $this->getMock(RefreshTokenRepositoryInterface::class);
+        $refreshTokenRepoMock = $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock();
        $refreshTokenRepoMock
            ->expects($this->once())
            ->method('getNewRefreshToken')
@@ -344,13 +342,13 @@ class AbstractGrantTest extends \PHPUnit_Framework_TestCase
        $accessToken = new AccessTokenEntity();
        /** @var RefreshTokenEntityInterface $refreshToken */
        $refreshToken = $issueRefreshTokenMethod->invoke($grantMock, $accessToken);
-        $this->assertTrue($refreshToken instanceof RefreshTokenEntityInterface);
+        $this->assertInstanceOf(RefreshTokenEntityInterface::class, $refreshToken);
        $this->assertEquals($accessToken, $refreshToken->getAccessToken());
    }

    public function testIssueAccessToken()
    {
-        $accessTokenRepoMock = $this->getMock(AccessTokenRepositoryInterface::class);
+        $accessTokenRepoMock = $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock();
        $accessTokenRepoMock->method('getNewToken')->willReturn(new AccessTokenEntity());

        /** @var AbstractGrant $grantMock */
@@ -369,12 +367,12 @@ class AbstractGrantTest extends \PHPUnit_Framework_TestCase
            123,
            [new ScopeEntity()]
        );
-        $this->assertTrue($accessToken instanceof AccessTokenEntityInterface);
+        $this->assertInstanceOf(AccessTokenEntityInterface::class, $accessToken);
    }

    public function testIssueAuthCode()
    {
-        $authCodeRepoMock = $this->getMock(AuthCodeRepositoryInterface::class);
+        $authCodeRepoMock = $this->getMockBuilder(AuthCodeRepositoryInterface::class)->getMock();
        $authCodeRepoMock->expects($this->once())->method('getNewAuthCode')->willReturn(new AuthCodeEntity());

        /** @var AbstractGrant $grantMock */
@@ -385,7 +383,8 @@ class AbstractGrantTest extends \PHPUnit_Framework_TestCase
        $issueAuthCodeMethod = $abstractGrantReflection->getMethod('issueAuthCode');
        $issueAuthCodeMethod->setAccessible(true);

-        $this->assertTrue(
+        $this->assertInstanceOf(
+            AuthCodeEntityInterface::class,
            $issueAuthCodeMethod->invoke(
                $grantMock,
                new \DateInterval('PT1H'),
@@ -393,7 +392,7 @@ class AbstractGrantTest extends \PHPUnit_Framework_TestCase
                123,
                'http://foo/bar',
                [new ScopeEntity()]
-            ) instanceof AuthCodeEntityInterface
+            )
        );
    }

@@ -469,7 +468,7 @@ class AbstractGrantTest extends \PHPUnit_Framework_TestCase
        $method = $abstractGrantReflection->getMethod('generateUniqueIdentifier');
        $method->setAccessible(true);

-        $this->assertTrue(is_string($method->invoke($grantMock)));
+        $this->assertInternalType('string', $method->invoke($grantMock));
    }

    public function testCanRespondToAuthorizationRequest()
--- a/tests/Grant/AuthCodeGrantTest.php
+++ b/tests/Grant/AuthCodeGrantTest.php
--- a/tests/Grant/ClientCredentialsGrantTest.php
+++ b/tests/Grant/ClientCredentialsGrantTest.php
@@ -9,11 +9,15 @@ use League\OAuth2\Server\Repositories\ClientRepositoryInterface;
 use League\OAuth2\Server\Repositories\ScopeRepositoryInterface;
 use LeagueTests\Stubs\AccessTokenEntity;
 use LeagueTests\Stubs\ClientEntity;
+use LeagueTests\Stubs\ScopeEntity;
 use LeagueTests\Stubs\StubResponseType;
+use PHPUnit\Framework\TestCase;
 use Zend\Diactoros\ServerRequest;

-class ClientCredentialsGrantTest extends \PHPUnit_Framework_TestCase
+class ClientCredentialsGrantTest extends TestCase
 {
+    const DEFAULT_SCOPE = 'basic';
+
    public function testGetIdentifier()
    {
        $grant = new ClientCredentialsGrant();
@@ -30,13 +34,16 @@ class ClientCredentialsGrantTest extends \PHPUnit_Framework_TestCase
        $accessTokenRepositoryMock->method('getNewToken')->willReturn(new AccessTokenEntity());
        $accessTokenRepositoryMock->method('persistNewAccessToken')->willReturnSelf();

+        $scope = new ScopeEntity();
        $scopeRepositoryMock = $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock();
+        $scopeRepositoryMock->method('getScopeEntityByIdentifier')->willReturn($scope);
        $scopeRepositoryMock->method('finalizeScopes')->willReturnArgument(0);

        $grant = new ClientCredentialsGrant();
        $grant->setClientRepository($clientRepositoryMock);
        $grant->setAccessTokenRepository($accessTokenRepositoryMock);
        $grant->setScopeRepository($scopeRepositoryMock);
+        $grant->setDefaultScope(self::DEFAULT_SCOPE);

        $serverRequest = new ServerRequest();
        $serverRequest = $serverRequest->withParsedBody(
@@ -49,6 +56,6 @@ class ClientCredentialsGrantTest extends \PHPUnit_Framework_TestCase
        $responseType = new StubResponseType();
        $grant->respondToAccessTokenRequest($serverRequest, $responseType, new \DateInterval('PT5M'));

-        $this->assertTrue($responseType->getAccessToken() instanceof AccessTokenEntityInterface);
+        $this->assertInstanceOf(AccessTokenEntityInterface::class, $responseType->getAccessToken());
    }
 }
--- a/tests/Grant/ImplicitGrantTest.php
+++ b/tests/Grant/ImplicitGrantTest.php
@@ -8,17 +8,23 @@ use League\OAuth2\Server\Exception\UniqueTokenIdentifierConstraintViolationExcep
 use League\OAuth2\Server\Grant\ImplicitGrant;
 use League\OAuth2\Server\Repositories\AccessTokenRepositoryInterface;
 use League\OAuth2\Server\Repositories\ClientRepositoryInterface;
+use League\OAuth2\Server\Repositories\RefreshTokenRepositoryInterface;
+use League\OAuth2\Server\Repositories\ScopeRepositoryInterface;
 use League\OAuth2\Server\RequestTypes\AuthorizationRequest;
 use League\OAuth2\Server\ResponseTypes\RedirectResponse;
 use LeagueTests\Stubs\AccessTokenEntity;
 use LeagueTests\Stubs\ClientEntity;
 use LeagueTests\Stubs\CryptTraitStub;
+use LeagueTests\Stubs\ScopeEntity;
 use LeagueTests\Stubs\StubResponseType;
 use LeagueTests\Stubs\UserEntity;
+use PHPUnit\Framework\TestCase;
 use Zend\Diactoros\ServerRequest;

-class ImplicitGrantTest extends \PHPUnit_Framework_TestCase
+class ImplicitGrantTest extends TestCase
 {
+    const DEFAULT_SCOPE = 'basic';
+
    /**
     * CryptTrait stub
     */
@@ -85,8 +91,14 @@ class ImplicitGrantTest extends \PHPUnit_Framework_TestCase
        $clientRepositoryMock = $this->getMockBuilder(ClientRepositoryInterface::class)->getMock();
        $clientRepositoryMock->method('getClientEntity')->willReturn($client);

+        $scopeRepositoryMock = $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock();
+        $scopeEntity = new ScopeEntity();
+        $scopeRepositoryMock->method('getScopeEntityByIdentifier')->willReturn($scopeEntity);
+
        $grant = new ImplicitGrant(new \DateInterval('PT10M'));
        $grant->setClientRepository($clientRepositoryMock);
+        $grant->setScopeRepository($scopeRepositoryMock);
+        $grant->setDefaultScope(self::DEFAULT_SCOPE);

        $request = new ServerRequest(
            [],
@@ -103,7 +115,7 @@ class ImplicitGrantTest extends \PHPUnit_Framework_TestCase
            ]
        );

-        $this->assertTrue($grant->validateAuthorizationRequest($request) instanceof AuthorizationRequest);
+        $this->assertInstanceOf(AuthorizationRequest::class, $grant->validateAuthorizationRequest($request));
    }

    public function testValidateAuthorizationRequestRedirectUriArray()
@@ -113,8 +125,14 @@ class ImplicitGrantTest extends \PHPUnit_Framework_TestCase
        $clientRepositoryMock = $this->getMockBuilder(ClientRepositoryInterface::class)->getMock();
        $clientRepositoryMock->method('getClientEntity')->willReturn($client);

+        $scopeRepositoryMock = $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock();
+        $scopeEntity = new ScopeEntity();
+        $scopeRepositoryMock->method('getScopeEntityByIdentifier')->willReturn($scopeEntity);
+
        $grant = new ImplicitGrant(new \DateInterval('PT10M'));
        $grant->setClientRepository($clientRepositoryMock);
+        $grant->setScopeRepository($scopeRepositoryMock);
+        $grant->setDefaultScope(self::DEFAULT_SCOPE);

        $request = new ServerRequest(
            [],
@@ -131,7 +149,7 @@ class ImplicitGrantTest extends \PHPUnit_Framework_TestCase
            ]
        );

-        $this->assertTrue($grant->validateAuthorizationRequest($request) instanceof AuthorizationRequest);
+        $this->assertInstanceOf(AuthorizationRequest::class, $grant->validateAuthorizationRequest($request));
    }

    /**
@@ -266,12 +284,15 @@ class ImplicitGrantTest extends \PHPUnit_Framework_TestCase
        $accessTokenRepositoryMock->method('getNewToken')->willReturn(new AccessTokenEntity());
        $accessTokenRepositoryMock->method('persistNewAccessToken')->willReturnSelf();

+        $scopeRepositoryMock = $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock();
+        $scopeRepositoryMock->method('finalizeScopes')->willReturnArgument(0);
+
        $grant = new ImplicitGrant(new \DateInterval('PT10M'));
        $grant->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));
-        $grant->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));
        $grant->setAccessTokenRepository($accessTokenRepositoryMock);
+        $grant->setScopeRepository($scopeRepositoryMock);

-        $this->assertTrue($grant->completeAuthorizationRequest($authRequest) instanceof RedirectResponse);
+        $this->assertInstanceOf(RedirectResponse::class, $grant->completeAuthorizationRequest($authRequest));
    }

    /**
@@ -290,10 +311,13 @@ class ImplicitGrantTest extends \PHPUnit_Framework_TestCase
        $accessTokenRepositoryMock->method('getNewToken')->willReturn(new AccessTokenEntity());
        $accessTokenRepositoryMock->method('persistNewAccessToken')->willReturnSelf();

+        $scopeRepositoryMock = $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock();
+        $scopeRepositoryMock->method('finalizeScopes')->willReturnArgument(0);
+
        $grant = new ImplicitGrant(new \DateInterval('PT10M'));
        $grant->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));
-        $grant->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));
        $grant->setAccessTokenRepository($accessTokenRepositoryMock);
+        $grant->setScopeRepository($scopeRepositoryMock);

        $grant->completeAuthorizationRequest($authRequest);
    }
@@ -312,12 +336,15 @@ class ImplicitGrantTest extends \PHPUnit_Framework_TestCase
        $accessTokenRepositoryMock->expects($this->at(0))->method('persistNewAccessToken')->willThrowException(UniqueTokenIdentifierConstraintViolationException::create());
        $accessTokenRepositoryMock->expects($this->at(1))->method('persistNewAccessToken')->willReturnSelf();

+        $scopeRepositoryMock = $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock();
+        $scopeRepositoryMock->method('finalizeScopes')->willReturnArgument(0);
+
        $grant = new ImplicitGrant(new \DateInterval('PT10M'));
        $grant->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));
-        $grant->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));
        $grant->setAccessTokenRepository($accessTokenRepositoryMock);
+        $grant->setScopeRepository($scopeRepositoryMock);

-        $this->assertTrue($grant->completeAuthorizationRequest($authRequest) instanceof RedirectResponse);
+        $this->assertInstanceOf(RedirectResponse::class, $grant->completeAuthorizationRequest($authRequest));
    }

    /**
@@ -337,10 +364,13 @@ class ImplicitGrantTest extends \PHPUnit_Framework_TestCase
        $accessTokenRepositoryMock->method('getNewToken')->willReturn(new AccessTokenEntity());
        $accessTokenRepositoryMock->method('persistNewAccessToken')->willThrowException(OAuthServerException::serverError('something bad happened'));

+        $scopeRepositoryMock = $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock();
+        $scopeRepositoryMock->method('finalizeScopes')->willReturnArgument(0);
+
        $grant = new ImplicitGrant(new \DateInterval('PT10M'));
        $grant->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));
-        $grant->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));
        $grant->setAccessTokenRepository($accessTokenRepositoryMock);
+        $grant->setScopeRepository($scopeRepositoryMock);

        $grant->completeAuthorizationRequest($authRequest);
    }
@@ -362,11 +392,42 @@ class ImplicitGrantTest extends \PHPUnit_Framework_TestCase
        $accessTokenRepositoryMock->method('getNewToken')->willReturn(new AccessTokenEntity());
        $accessTokenRepositoryMock->method('persistNewAccessToken')->willThrowException(UniqueTokenIdentifierConstraintViolationException::create());

+        $scopeRepositoryMock = $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock();
+        $scopeRepositoryMock->method('finalizeScopes')->willReturnArgument(0);
+
        $grant = new ImplicitGrant(new \DateInterval('PT10M'));
        $grant->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));
-        $grant->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));
        $grant->setAccessTokenRepository($accessTokenRepositoryMock);
+        $grant->setScopeRepository($scopeRepositoryMock);

        $grant->completeAuthorizationRequest($authRequest);
    }
+
+    /**
+     * @expectedException \LogicException
+     */
+    public function testSetRefreshTokenTTL()
+    {
+        $grant = new ImplicitGrant(new \DateInterval('PT10M'));
+        $grant->setRefreshTokenTTL(new \DateInterval('PT10M'));
+    }
+
+    /**
+     * @expectedException \LogicException
+     */
+    public function testSetRefreshTokenRepository()
+    {
+        $grant = new ImplicitGrant(new \DateInterval('PT10M'));
+        $refreshTokenRepositoryMock = $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock();
+        $grant->setRefreshTokenRepository($refreshTokenRepositoryMock);
+    }
+
+    /**
+     * @expectedException \LogicException
+     */
+    public function testCompleteAuthorizationRequestNoUser()
+    {
+        $grant = new ImplicitGrant(new \DateInterval('PT10M'));
+        $grant->completeAuthorizationRequest(new AuthorizationRequest());
+    }
 }
--- a/tests/Grant/PasswordGrantTest.php
+++ b/tests/Grant/PasswordGrantTest.php
@@ -13,16 +13,20 @@ use League\OAuth2\Server\Repositories\UserRepositoryInterface;
 use LeagueTests\Stubs\AccessTokenEntity;
 use LeagueTests\Stubs\ClientEntity;
 use LeagueTests\Stubs\RefreshTokenEntity;
+use LeagueTests\Stubs\ScopeEntity;
 use LeagueTests\Stubs\StubResponseType;
 use LeagueTests\Stubs\UserEntity;
+use PHPUnit\Framework\TestCase;
 use Zend\Diactoros\ServerRequest;

-class PasswordGrantTest extends \PHPUnit_Framework_TestCase
+class PasswordGrantTest extends TestCase
 {
+    const DEFAULT_SCOPE = 'basic';
+
    public function testGetIdentifier()
    {
-        $userRepositoryMock = $this->getMock(UserRepositoryInterface::class);
-        $refreshTokenRepositoryMock = $this->getMock(RefreshTokenRepositoryInterface::class);
+        $userRepositoryMock = $this->getMockBuilder(UserRepositoryInterface::class)->getMock();
+        $refreshTokenRepositoryMock = $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock();

        $grant = new PasswordGrant($userRepositoryMock, $refreshTokenRepositoryMock);
        $this->assertEquals('password', $grant->getIdentifier());
@@ -46,13 +50,16 @@ class PasswordGrantTest extends \PHPUnit_Framework_TestCase
        $refreshTokenRepositoryMock->method('persistNewRefreshToken')->willReturnSelf();
        $refreshTokenRepositoryMock->method('getNewRefreshToken')->willReturn(new RefreshTokenEntity());

+        $scope = new ScopeEntity();
        $scopeRepositoryMock = $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock();
+        $scopeRepositoryMock->method('getScopeEntityByIdentifier')->willReturn($scope);
        $scopeRepositoryMock->method('finalizeScopes')->willReturnArgument(0);

        $grant = new PasswordGrant($userRepositoryMock, $refreshTokenRepositoryMock);
        $grant->setClientRepository($clientRepositoryMock);
        $grant->setAccessTokenRepository($accessTokenRepositoryMock);
        $grant->setScopeRepository($scopeRepositoryMock);
+        $grant->setDefaultScope(self::DEFAULT_SCOPE);

        $serverRequest = new ServerRequest();
        $serverRequest = $serverRequest->withParsedBody(
@@ -67,8 +74,8 @@ class PasswordGrantTest extends \PHPUnit_Framework_TestCase
        $responseType = new StubResponseType();
        $grant->respondToAccessTokenRequest($serverRequest, $responseType, new \DateInterval('PT5M'));

-        $this->assertTrue($responseType->getAccessToken() instanceof AccessTokenEntityInterface);
-        $this->assertTrue($responseType->getRefreshToken() instanceof RefreshTokenEntityInterface);
+        $this->assertInstanceOf(AccessTokenEntityInterface::class, $responseType->getAccessToken());
+        $this->assertInstanceOf(RefreshTokenEntityInterface::class, $responseType->getRefreshToken());
    }

    /**
--- a/tests/Grant/RefreshTokenGrantTest.php
+++ b/tests/Grant/RefreshTokenGrantTest.php
@@ -16,12 +16,13 @@ use LeagueTests\Stubs\CryptTraitStub;
 use LeagueTests\Stubs\RefreshTokenEntity;
 use LeagueTests\Stubs\ScopeEntity;
 use LeagueTests\Stubs\StubResponseType;
+use PHPUnit\Framework\TestCase;
 use Zend\Diactoros\ServerRequest;

-class RefreshTokenGrantTest extends \PHPUnit_Framework_TestCase
+class RefreshTokenGrantTest extends TestCase
 {
    /**
-     * CryptTrait stub
+     * @var CryptTraitStub
     */
    protected $cryptStub;

@@ -32,7 +33,7 @@ class RefreshTokenGrantTest extends \PHPUnit_Framework_TestCase

    public function testGetIdentifier()
    {
-        $refreshTokenRepositoryMock = $this->getMock(RefreshTokenRepositoryInterface::class);
+        $refreshTokenRepositoryMock = $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock();

        $grant = new RefreshTokenGrant($refreshTokenRepositoryMock);
        $this->assertEquals('refresh_token', $grant->getIdentifier());
@@ -45,27 +46,24 @@ class RefreshTokenGrantTest extends \PHPUnit_Framework_TestCase
        $clientRepositoryMock = $this->getMockBuilder(ClientRepositoryInterface::class)->getMock();
        $clientRepositoryMock->method('getClientEntity')->willReturn($client);

-        $scopeRepositoryMock = $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock();
        $scopeEntity = new ScopeEntity();
+        $scopeEntity->setIdentifier('foo');
+        $scopeRepositoryMock = $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock();
        $scopeRepositoryMock->method('getScopeEntityByIdentifier')->willReturn($scopeEntity);

        $accessTokenRepositoryMock = $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock();
        $accessTokenRepositoryMock->method('getNewToken')->willReturn(new AccessTokenEntity());
-        $accessTokenRepositoryMock
-            ->expects($this->once())
-            ->method('persistNewAccessToken')->willReturnSelf();
+        $accessTokenRepositoryMock->expects($this->once())->method('persistNewAccessToken')->willReturnSelf();

        $refreshTokenRepositoryMock = $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock();
        $refreshTokenRepositoryMock->method('getNewRefreshToken')->willReturn(new RefreshTokenEntity());
-        $refreshTokenRepositoryMock
-            ->expects($this->once())
-            ->method('persistNewRefreshToken')->willReturnSelf();
+        $refreshTokenRepositoryMock->expects($this->once())->method('persistNewRefreshToken')->willReturnSelf();

        $grant = new RefreshTokenGrant($refreshTokenRepositoryMock);
        $grant->setClientRepository($clientRepositoryMock);
        $grant->setScopeRepository($scopeRepositoryMock);
        $grant->setAccessTokenRepository($accessTokenRepositoryMock);
-        $grant->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));
+        $grant->setEncryptionKey($this->cryptStub->getKey());
        $grant->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));

        $oldRefreshToken = $this->cryptStub->doEncrypt(
@@ -82,19 +80,18 @@ class RefreshTokenGrantTest extends \PHPUnit_Framework_TestCase
        );

        $serverRequest = new ServerRequest();
-        $serverRequest = $serverRequest->withParsedBody(
-            [
-                'client_id'     => 'foo',
-                'client_secret' => 'bar',
-                'refresh_token' => $oldRefreshToken,
-            ]
-        );
+        $serverRequest = $serverRequest->withParsedBody([
+            'client_id'     => 'foo',
+            'client_secret' => 'bar',
+            'refresh_token' => $oldRefreshToken,
+            'scopes'        => ['foo'],
+        ]);

        $responseType = new StubResponseType();
        $grant->respondToAccessTokenRequest($serverRequest, $responseType, new \DateInterval('PT5M'));

-        $this->assertTrue($responseType->getAccessToken() instanceof AccessTokenEntityInterface);
-        $this->assertTrue($responseType->getRefreshToken() instanceof RefreshTokenEntityInterface);
+        $this->assertInstanceOf(AccessTokenEntityInterface::class, $responseType->getAccessToken());
+        $this->assertInstanceOf(RefreshTokenEntityInterface::class, $responseType->getRefreshToken());
    }

    public function testRespondToReducedScopes()
@@ -121,7 +118,7 @@ class RefreshTokenGrantTest extends \PHPUnit_Framework_TestCase
        $grant->setClientRepository($clientRepositoryMock);
        $grant->setAccessTokenRepository($accessTokenRepositoryMock);
        $grant->setScopeRepository($scopeRepositoryMock);
-        $grant->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));
+        $grant->setEncryptionKey($this->cryptStub->getKey());
        $grant->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));

        $oldRefreshToken = $this->cryptStub->doEncrypt(
@@ -150,8 +147,8 @@ class RefreshTokenGrantTest extends \PHPUnit_Framework_TestCase
        $responseType = new StubResponseType();
        $grant->respondToAccessTokenRequest($serverRequest, $responseType, new \DateInterval('PT5M'));

-        $this->assertTrue($responseType->getAccessToken() instanceof AccessTokenEntityInterface);
-        $this->assertTrue($responseType->getRefreshToken() instanceof RefreshTokenEntityInterface);
+        $this->assertInstanceOf(AccessTokenEntityInterface::class, $responseType->getAccessToken());
+        $this->assertInstanceOf(RefreshTokenEntityInterface::class, $responseType->getRefreshToken());
    }

    /**
@@ -180,7 +177,7 @@ class RefreshTokenGrantTest extends \PHPUnit_Framework_TestCase
        $grant->setClientRepository($clientRepositoryMock);
        $grant->setAccessTokenRepository($accessTokenRepositoryMock);
        $grant->setScopeRepository($scopeRepositoryMock);
-        $grant->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));
+        $grant->setEncryptionKey($this->cryptStub->getKey());
        $grant->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));

        $oldRefreshToken = $this->cryptStub->doEncrypt(
@@ -227,7 +224,7 @@ class RefreshTokenGrantTest extends \PHPUnit_Framework_TestCase
        $grant = new RefreshTokenGrant($refreshTokenRepositoryMock);
        $grant->setClientRepository($clientRepositoryMock);
        $grant->setAccessTokenRepository($accessTokenRepositoryMock);
-        $grant->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));
+        $grant->setEncryptionKey($this->cryptStub->getKey());
        $grant->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));

        $serverRequest = new ServerRequest();
@@ -259,7 +256,7 @@ class RefreshTokenGrantTest extends \PHPUnit_Framework_TestCase
        $grant = new RefreshTokenGrant($refreshTokenRepositoryMock);
        $grant->setClientRepository($clientRepositoryMock);
        $grant->setAccessTokenRepository($accessTokenRepositoryMock);
-        $grant->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));
+        $grant->setEncryptionKey($this->cryptStub->getKey());
        $grant->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));

        $oldRefreshToken = 'foobar';
@@ -291,14 +288,13 @@ class RefreshTokenGrantTest extends \PHPUnit_Framework_TestCase
        $accessTokenRepositoryMock = $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock();
        $accessTokenRepositoryMock->method('persistNewAccessToken')->willReturnSelf();

-
        $refreshTokenRepositoryMock = $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock();
        $refreshTokenRepositoryMock->method('persistNewRefreshToken')->willReturnSelf();

        $grant = new RefreshTokenGrant($refreshTokenRepositoryMock);
        $grant->setClientRepository($clientRepositoryMock);
        $grant->setAccessTokenRepository($accessTokenRepositoryMock);
-        $grant->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));
+        $grant->setEncryptionKey($this->cryptStub->getKey());
        $grant->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));

        $oldRefreshToken = $this->cryptStub->doEncrypt(
@@ -344,7 +340,7 @@ class RefreshTokenGrantTest extends \PHPUnit_Framework_TestCase
        $grant = new RefreshTokenGrant($refreshTokenRepositoryMock);
        $grant->setClientRepository($clientRepositoryMock);
        $grant->setAccessTokenRepository($accessTokenRepositoryMock);
-        $grant->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));
+        $grant->setEncryptionKey($this->cryptStub->getKey());
        $grant->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));

        $oldRefreshToken = $this->cryptStub->doEncrypt(
@@ -391,7 +387,7 @@ class RefreshTokenGrantTest extends \PHPUnit_Framework_TestCase
        $grant = new RefreshTokenGrant($refreshTokenRepositoryMock);
        $grant->setClientRepository($clientRepositoryMock);
        $grant->setAccessTokenRepository($accessTokenRepositoryMock);
-        $grant->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));
+        $grant->setEncryptionKey($this->cryptStub->getKey());
        $grant->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));

        $oldRefreshToken = $this->cryptStub->doEncrypt(
--- a/tests/Middleware/AuthorizationServerMiddlewareTest.php
+++ b/tests/Middleware/AuthorizationServerMiddlewareTest.php
@@ -11,21 +11,27 @@ use League\OAuth2\Server\Repositories\ClientRepositoryInterface;
 use League\OAuth2\Server\Repositories\ScopeRepositoryInterface;
 use LeagueTests\Stubs\AccessTokenEntity;
 use LeagueTests\Stubs\ClientEntity;
+use LeagueTests\Stubs\ScopeEntity;
 use LeagueTests\Stubs\StubResponseType;
+use PHPUnit\Framework\TestCase;
 use Zend\Diactoros\Response;
 use Zend\Diactoros\ServerRequestFactory;

-class AuthorizationServerMiddlewareTest extends \PHPUnit_Framework_TestCase
+class AuthorizationServerMiddlewareTest extends TestCase
 {
+    const DEFAULT_SCOPE = 'basic';
+
    public function testValidResponse()
    {
-        $clientRepository = $this->getMock(ClientRepositoryInterface::class);
+        $clientRepository = $this->getMockBuilder(ClientRepositoryInterface::class)->getMock();
        $clientRepository->method('getClientEntity')->willReturn(new ClientEntity());

+        $scopeEntity = new ScopeEntity;
        $scopeRepositoryMock = $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock();
+        $scopeRepositoryMock->method('getScopeEntityByIdentifier')->willReturn($scopeEntity);
        $scopeRepositoryMock->method('finalizeScopes')->willReturnArgument(0);

-        $accessRepositoryMock = $this->getMock(AccessTokenRepositoryInterface::class);
+        $accessRepositoryMock = $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock();
        $accessRepositoryMock->method('getNewToken')->willReturn(new AccessTokenEntity());

        $server = new AuthorizationServer(
@@ -33,10 +39,11 @@ class AuthorizationServerMiddlewareTest extends \PHPUnit_Framework_TestCase
            $accessRepositoryMock,
            $scopeRepositoryMock,
            'file://' . __DIR__ . '/../Stubs/private.key',
-            'file://' . __DIR__ . '/../Stubs/public.key',
+            base64_encode(random_bytes(36)),
            new StubResponseType()
        );

+        $server->setDefaultScope(self::DEFAULT_SCOPE);
        $server->enableGrantType(new ClientCredentialsGrant());

        $_POST['grant_type'] = 'client_credentials';
@@ -58,15 +65,15 @@ class AuthorizationServerMiddlewareTest extends \PHPUnit_Framework_TestCase

    public function testOAuthErrorResponse()
    {
-        $clientRepository = $this->getMock(ClientRepositoryInterface::class);
+        $clientRepository = $this->getMockBuilder(ClientRepositoryInterface::class)->getMock();
        $clientRepository->method('getClientEntity')->willReturn(null);

        $server = new AuthorizationServer(
            $clientRepository,
-            $this->getMock(AccessTokenRepositoryInterface::class),
-            $this->getMock(ScopeRepositoryInterface::class),
+            $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock(),
+            $this->getMockBuilder(ScopeRepositoryInterface::class)->getMock(),
            'file://' . __DIR__ . '/../Stubs/private.key',
-            'file://' . __DIR__ . '/../Stubs/public.key',
+            base64_encode(random_bytes(36)),
            new StubResponseType()
        );

@@ -97,7 +104,8 @@ class AuthorizationServerMiddlewareTest extends \PHPUnit_Framework_TestCase
        $response = $exception->generateHttpResponse(new Response());

        $this->assertEquals(302, $response->getStatusCode());
-        $this->assertEquals('http://foo/bar?error=invalid_scope&message=The+requested+scope+is+invalid%2C+unknown%2C+or+malformed&hint=Check+the+%60test%60+scope', $response->getHeader('location')[0]);
+        $this->assertEquals('http://foo/bar?error=invalid_scope&error_description=The+requested+scope+is+invalid%2C+unknown%2C+or+malformed&hint=Check+the+%60test%60+scope&message=The+requested+scope+is+invalid%2C+unknown%2C+or+malformed',
+            $response->getHeader('location')[0]);
    }

    public function testOAuthErrorResponseRedirectUriFragment()
@@ -106,6 +114,7 @@ class AuthorizationServerMiddlewareTest extends \PHPUnit_Framework_TestCase
        $response = $exception->generateHttpResponse(new Response(), true);

        $this->assertEquals(302, $response->getStatusCode());
-        $this->assertEquals('http://foo/bar#error=invalid_scope&message=The+requested+scope+is+invalid%2C+unknown%2C+or+malformed&hint=Check+the+%60test%60+scope', $response->getHeader('location')[0]);
+        $this->assertEquals('http://foo/bar#error=invalid_scope&error_description=The+requested+scope+is+invalid%2C+unknown%2C+or+malformed&hint=Check+the+%60test%60+scope&message=The+requested+scope+is+invalid%2C+unknown%2C+or+malformed',
+            $response->getHeader('location')[0]);
    }
 }
--- a/tests/Middleware/ResourceServerMiddlewareTest.php
+++ b/tests/Middleware/ResourceServerMiddlewareTest.php
@@ -8,15 +8,16 @@ use League\OAuth2\Server\Repositories\AccessTokenRepositoryInterface;
 use League\OAuth2\Server\ResourceServer;
 use LeagueTests\Stubs\AccessTokenEntity;
 use LeagueTests\Stubs\ClientEntity;
+use PHPUnit\Framework\TestCase;
 use Zend\Diactoros\Response;
 use Zend\Diactoros\ServerRequest;

-class ResourceServerMiddlewareTest extends \PHPUnit_Framework_TestCase
+class ResourceServerMiddlewareTest extends TestCase
 {
    public function testValidResponse()
    {
        $server = new ResourceServer(
-            $this->getMock(AccessTokenRepositoryInterface::class),
+            $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock(),
            'file://' . __DIR__ . '/../Stubs/public.key'
        );

@@ -51,7 +52,7 @@ class ResourceServerMiddlewareTest extends \PHPUnit_Framework_TestCase
    public function testValidResponseExpiredToken()
    {
        $server = new ResourceServer(
-            $this->getMock(AccessTokenRepositoryInterface::class),
+            $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock(),
            'file://' . __DIR__ . '/../Stubs/public.key'
        );

@@ -86,7 +87,7 @@ class ResourceServerMiddlewareTest extends \PHPUnit_Framework_TestCase
    public function testErrorResponse()
    {
        $server = new ResourceServer(
-            $this->getMock(AccessTokenRepositoryInterface::class),
+            $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock(),
            'file://' . __DIR__ . '/../Stubs/public.key'
        );

--- a/tests/PHPStan/AbstractGrantExtension.php
+++ b/tests/PHPStan/AbstractGrantExtension.php
@@ -0,0 +1,39 @@
+<?php
+declare(strict_types = 1);
+
+namespace LeagueTests\PHPStan;
+
+use League\OAuth2\Server\Grant\AbstractGrant;
+use PhpParser\Node\Expr\MethodCall;
+use PHPStan\Analyser\Scope;
+use PHPStan\Reflection\MethodReflection;
+use PHPStan\Type\DynamicMethodReturnTypeExtension;
+use PHPStan\Type\NullType;
+use PHPStan\Type\StringType;
+use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
+
+final class AbstractGrantExtension implements DynamicMethodReturnTypeExtension
+{
+    public function getClass(): string
+    {
+        return AbstractGrant::class;
+    }
+
+    public function isMethodSupported(MethodReflection $methodReflection): bool
+    {
+        return in_array($methodReflection->getName(), [
+            'getRequestParameter',
+            'getQueryStringParameter',
+            'getCookieParameter',
+        ], true);
+    }
+
+    public function getTypeFromMethodCall(MethodReflection $methodReflection, MethodCall $methodCall, Scope $scope): Type
+    {
+        return TypeCombinator::union(...[
+            new StringType(),
+            isset($methodCall->args[2]) ? $scope->getType($methodCall->args[2]->value) : new NullType(),
+        ]);
+    }
+}
--- a/tests/ResourceServerTest.php
+++ b/tests/ResourceServerTest.php
@@ -6,14 +6,15 @@ namespace LeagueTests;
 use League\OAuth2\Server\Exception\OAuthServerException;
 use League\OAuth2\Server\Repositories\AccessTokenRepositoryInterface;
 use League\OAuth2\Server\ResourceServer;
+use PHPUnit\Framework\TestCase;
 use Zend\Diactoros\ServerRequestFactory;

-class ResourceServerTest extends \PHPUnit_Framework_TestCase
+class ResourceServerTest extends TestCase
 {
    public function testValidateAuthenticatedRequest()
    {
        $server = new ResourceServer(
-            $this->getMock(AccessTokenRepositoryInterface::class),
+            $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock(),
            'file://' . __DIR__ . '/Stubs/public.key'
        );

--- a/tests/ResponseTypes/BearerResponseTypeTest.php
+++ b/tests/ResponseTypes/BearerResponseTypeTest.php
@@ -11,19 +11,18 @@ use LeagueTests\Stubs\AccessTokenEntity;
 use LeagueTests\Stubs\ClientEntity;
 use LeagueTests\Stubs\RefreshTokenEntity;
 use LeagueTests\Stubs\ScopeEntity;
+use PHPUnit\Framework\TestCase;
 use Psr\Http\Message\ResponseInterface;
 use Zend\Diactoros\Response;
 use Zend\Diactoros\ServerRequest;

-class BearerResponseTypeTest extends \PHPUnit_Framework_TestCase
+class BearerResponseTypeTest extends TestCase
 {
    public function testGenerateHttpResponse()
    {
-        $accessTokenRepositoryMock = $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock();
-
-        $responseType = new BearerTokenResponse($accessTokenRepositoryMock);
+        $responseType = new BearerTokenResponse();
        $responseType->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));
-        $responseType->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));
+        $responseType->setEncryptionKey(base64_encode(random_bytes(36)));

        $client = new ClientEntity();
        $client->setIdentifier('clientName');
@@ -47,7 +46,7 @@ class BearerResponseTypeTest extends \PHPUnit_Framework_TestCase

        $response = $responseType->generateHttpResponse(new Response());

-        $this->assertTrue($response instanceof ResponseInterface);
+        $this->assertInstanceOf(ResponseInterface::class, $response);
        $this->assertEquals(200, $response->getStatusCode());
        $this->assertEquals('no-cache', $response->getHeader('pragma')[0]);
        $this->assertEquals('no-store', $response->getHeader('cache-control')[0]);
@@ -55,20 +54,62 @@ class BearerResponseTypeTest extends \PHPUnit_Framework_TestCase

        $response->getBody()->rewind();
        $json = json_decode($response->getBody()->getContents());
-        $this->assertEquals('Bearer', $json->token_type);
-        $this->assertTrue(isset($json->expires_in));
-        $this->assertTrue(isset($json->access_token));
-        $this->assertTrue(isset($json->refresh_token));
+        $this->assertAttributeEquals('Bearer', 'token_type', $json);
+        $this->assertObjectHasAttribute('expires_in', $json);
+        $this->assertObjectHasAttribute('access_token', $json);
+        $this->assertObjectHasAttribute('refresh_token', $json);
+    }
+
+    public function testGenerateHttpResponseWithExtraParams()
+    {
+        $responseType = new BearerTokenResponseWithParams();
+        $responseType->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));
+        $responseType->setEncryptionKey(base64_encode(random_bytes(36)));
+
+        $client = new ClientEntity();
+        $client->setIdentifier('clientName');
+
+        $scope = new ScopeEntity();
+        $scope->setIdentifier('basic');
+
+        $accessToken = new AccessTokenEntity();
+        $accessToken->setIdentifier('abcdef');
+        $accessToken->setExpiryDateTime((new \DateTime())->add(new \DateInterval('PT1H')));
+        $accessToken->setClient($client);
+        $accessToken->addScope($scope);
+
+        $refreshToken = new RefreshTokenEntity();
+        $refreshToken->setIdentifier('abcdef');
+        $refreshToken->setAccessToken($accessToken);
+        $refreshToken->setExpiryDateTime((new \DateTime())->add(new \DateInterval('PT1H')));
+
+        $responseType->setAccessToken($accessToken);
+        $responseType->setRefreshToken($refreshToken);
+
+        $response = $responseType->generateHttpResponse(new Response());
+
+        $this->assertInstanceOf(ResponseInterface::class, $response);
+        $this->assertEquals(200, $response->getStatusCode());
+        $this->assertEquals('no-cache', $response->getHeader('pragma')[0]);
+        $this->assertEquals('no-store', $response->getHeader('cache-control')[0]);
+        $this->assertEquals('application/json; charset=UTF-8', $response->getHeader('content-type')[0]);
+
+        $response->getBody()->rewind();
+        $json = json_decode($response->getBody()->getContents());
+        $this->assertAttributeEquals('Bearer', 'token_type', $json);
+        $this->assertObjectHasAttribute('expires_in', $json);
+        $this->assertObjectHasAttribute('access_token', $json);
+        $this->assertObjectHasAttribute('refresh_token', $json);
+
+        $this->assertObjectHasAttribute('foo', $json);
+        $this->assertAttributeEquals('bar', 'foo', $json);
    }

    public function testDetermineAccessTokenInHeaderValidToken()
    {
-        $accessTokenRepositoryMock = $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock();
-        $accessTokenRepositoryMock->method('isAccessTokenRevoked')->willReturn(false);
-
-        $responseType = new BearerTokenResponse($accessTokenRepositoryMock);
+        $responseType = new BearerTokenResponse();
        $responseType->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));
-        $responseType->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));
+        $responseType->setEncryptionKey(base64_encode(random_bytes(36)));

        $client = new ClientEntity();
        $client->setIdentifier('clientName');
@@ -94,7 +135,6 @@ class BearerResponseTypeTest extends \PHPUnit_Framework_TestCase
        $accessTokenRepositoryMock->method('isAccessTokenRevoked')->willReturn(false);

        $authorizationValidator = new BearerTokenValidator($accessTokenRepositoryMock);
-        $authorizationValidator->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));
        $authorizationValidator->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));

        $request = new ServerRequest();
@@ -111,11 +151,10 @@ class BearerResponseTypeTest extends \PHPUnit_Framework_TestCase
    public function testDetermineAccessTokenInHeaderInvalidJWT()
    {
        $accessTokenRepositoryMock = $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock();
-        $accessTokenRepositoryMock->method('isAccessTokenRevoked')->willReturn(false);

-        $responseType = new BearerTokenResponse($accessTokenRepositoryMock);
+        $responseType = new BearerTokenResponse();
        $responseType->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));
-        $responseType->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));
+        $responseType->setEncryptionKey(base64_encode(random_bytes(36)));

        $client = new ClientEntity();
        $client->setIdentifier('clientName');
@@ -138,7 +177,6 @@ class BearerResponseTypeTest extends \PHPUnit_Framework_TestCase
        $json = json_decode((string) $response->getBody());

        $authorizationValidator = new BearerTokenValidator($accessTokenRepositoryMock);
-        $authorizationValidator->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));
        $authorizationValidator->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));

        $request = new ServerRequest();
@@ -158,7 +196,7 @@ class BearerResponseTypeTest extends \PHPUnit_Framework_TestCase
    {
        $responseType = new BearerTokenResponse();
        $responseType->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));
-        $responseType->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));
+        $responseType->setEncryptionKey(base64_encode(random_bytes(36)));

        $client = new ClientEntity();
        $client->setIdentifier('clientName');
@@ -184,7 +222,6 @@ class BearerResponseTypeTest extends \PHPUnit_Framework_TestCase
        $accessTokenRepositoryMock->method('isAccessTokenRevoked')->willReturn(true);

        $authorizationValidator = new BearerTokenValidator($accessTokenRepositoryMock);
-        $authorizationValidator->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));
        $authorizationValidator->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));

        $request = new ServerRequest();
@@ -202,16 +239,13 @@ class BearerResponseTypeTest extends \PHPUnit_Framework_TestCase

    public function testDetermineAccessTokenInHeaderInvalidToken()
    {
-        $accessTokenRepositoryMock = $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock();
-
-        $responseType = new BearerTokenResponse($accessTokenRepositoryMock);
+        $responseType = new BearerTokenResponse();
        $responseType->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));
-        $responseType->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));
+        $responseType->setEncryptionKey(base64_encode(random_bytes(36)));

        $accessTokenRepositoryMock = $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock();

        $authorizationValidator = new BearerTokenValidator($accessTokenRepositoryMock);
-        $authorizationValidator->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));
        $authorizationValidator->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));

        $request = new ServerRequest();
@@ -226,19 +260,16 @@ class BearerResponseTypeTest extends \PHPUnit_Framework_TestCase
            );
        }
    }
-    
+
    public function testDetermineMissingBearerInHeader()
    {
-        $accessTokenRepositoryMock = $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock();
-
-        $responseType = new BearerTokenResponse($accessTokenRepositoryMock);
+        $responseType = new BearerTokenResponse();
        $responseType->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));
-        $responseType->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));
+        $responseType->setEncryptionKey(base64_encode(random_bytes(36)));

        $accessTokenRepositoryMock = $this->getMockBuilder(AccessTokenRepositoryInterface::class)->getMock();

        $authorizationValidator = new BearerTokenValidator($accessTokenRepositoryMock);
-        $authorizationValidator->setPrivateKey(new CryptKey('file://' . __DIR__ . '/../Stubs/private.key'));
        $authorizationValidator->setPublicKey(new CryptKey('file://' . __DIR__ . '/../Stubs/public.key'));

        $request = new ServerRequest();
--- a/tests/ResponseTypes/BearerTokenResponseWithParams.php
+++ b/tests/ResponseTypes/BearerTokenResponseWithParams.php
@@ -0,0 +1,14 @@
+<?php
+
+namespace LeagueTests\ResponseTypes;
+
+use League\OAuth2\Server\Entities\AccessTokenEntityInterface;
+use League\OAuth2\Server\ResponseTypes\BearerTokenResponse;
+
+class BearerTokenResponseWithParams extends BearerTokenResponse
+{
+    protected function getExtraParams(AccessTokenEntityInterface $accessToken)
+    {
+        return ['foo' => 'bar', 'token_type' => 'Should not overwrite'];
+    }
+}
--- a/tests/Stubs/.gitattributes
+++ b/tests/Stubs/.gitattributes
@@ -0,0 +1 @@
+private.key.crlf text eol=crlf
--- a/tests/Stubs/CryptTraitStub.php
+++ b/tests/Stubs/CryptTraitStub.php
@@ -2,7 +2,6 @@

 namespace LeagueTests\Stubs;

-use League\OAuth2\Server\CryptKey;
 use League\OAuth2\Server\CryptTrait;

 class CryptTraitStub
@@ -11,8 +10,12 @@ class CryptTraitStub

    public function __construct()
    {
-        $this->setPrivateKey(new CryptKey('file://' . __DIR__ . '/private.key'));
-        $this->setPublicKey(new CryptKey('file://' . __DIR__ . '/public.key'));
+        $this->setEncryptionKey(base64_encode(random_bytes(36)));
+    }
+
+    public function getKey()
+    {
+        return $this->encryptionKey;
    }

    public function doEncrypt($unencryptedData)
--- a/tests/Stubs/private.key.crlf
+++ b/tests/Stubs/private.key.crlf
@@ -0,0 +1,27 @@
+-----BEGIN RSA PRIVATE KEY-----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+-----END RSA PRIVATE KEY-----
--- a/tests/Utils/CryptKeyTest.php
+++ b/tests/Utils/CryptKeyTest.php
@@ -0,0 +1,45 @@
+<?php
+
+namespace LeagueTests\Utils;
+
+use League\OAuth2\Server\CryptKey;
+use PHPUnit\Framework\TestCase;
+
+class CryptKeyTest extends TestCase
+{
+    /**
+     * @expectedException \LogicException
+     */
+    public function testNoFile()
+    {
+        new CryptKey('undefined file');
+    }
+
+    public function testKeyCreation()
+    {
+        $keyFile = __DIR__ . '/../Stubs/public.key';
+        $key = new CryptKey($keyFile, 'secret');
+
+        $this->assertEquals('file://' . $keyFile, $key->getKeyPath());
+        $this->assertEquals('secret', $key->getPassPhrase());
+    }
+
+    public function testKeyFileCreation()
+    {
+        $keyContent = file_get_contents(__DIR__ . '/../Stubs/public.key');
+        $key = new CryptKey($keyContent);
+
+        $this->assertEquals(
+            'file://' . sys_get_temp_dir() . '/' . sha1($keyContent) . '.key',
+            $key->getKeyPath()
+        );
+
+        $keyContent = file_get_contents(__DIR__ . '/../Stubs/private.key.crlf');
+        $key = new CryptKey($keyContent);
+
+        $this->assertEquals(
+            'file://' . sys_get_temp_dir() . '/' . sha1($keyContent) . '.key',
+            $key->getKeyPath()
+        );
+    }
+}
--- a/tests/Utils/CryptTraitTest.php
+++ b/tests/Utils/CryptTraitTest.php
@@ -0,0 +1,41 @@
+<?php
+
+namespace LeagueTests\Utils;
+
+use Defuse\Crypto\Key;
+use LeagueTests\Stubs\CryptTraitStub;
+use PHPUnit\Framework\TestCase;
+
+class CryptTraitTest extends TestCase
+{
+    protected $cryptStub;
+
+    protected function setUp()
+    {
+        $this->cryptStub = new CryptTraitStub();
+    }
+
+    public function testEncryptDecryptWithPassword()
+    {
+        $this->cryptStub->setEncryptionKey(base64_encode(random_bytes(36)));
+
+        $this->encryptDecrypt();
+    }
+
+    public function testEncryptDecryptWithKey()
+    {
+        $this->cryptStub->setEncryptionKey(Key::createNewRandomKey());
+
+        $this->encryptDecrypt();
+    }
+
+    private function encryptDecrypt()
+    {
+        $payload = 'alex loves whisky';
+        $encrypted = $this->cryptStub->doEncrypt($payload);
+        $plainText = $this->cryptStub->doDecrypt($encrypted);
+
+        $this->assertNotEquals($payload, $encrypted);
+        $this->assertEquals($payload, $plainText);
+    }
+}