From c41e659383141da2adbadcf8d92f1dbee83ae269 Mon Sep 17 00:00:00 2001 From: Daniel Micay Date: Sat, 25 Aug 2018 23:00:00 -0400 Subject: [PATCH] use ChaCha8-based CSPRNG --- Makefile | 5 +- chacha.c | 188 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ chacha.h | 18 ++++++ random.c | 24 +++++-- random.h | 7 ++- 5 files changed, 235 insertions(+), 7 deletions(-) create mode 100644 chacha.c create mode 100644 chacha.h diff --git a/Makefile b/Makefile index 8405f16..b4cd66a 100644 --- a/Makefile +++ b/Makefile @@ -2,14 +2,15 @@ CPPFLAGS := -D_GNU_SOURCE CFLAGS := -std=c11 -Wall -Wextra -O2 -flto -fPIC -fvisibility=hidden -pedantic LDFLAGS := -Wl,--as-needed LDLIBS := -lpthread -OBJECTS := malloc.o random.o util.o +OBJECTS := chacha.o malloc.o random.o util.o hardened_malloc.so: $(OBJECTS) $(CC) $(CFLAGS) $(LDFLAGS) -shared $^ $(LDLIBS) -o $@ malloc.o: malloc.c malloc.h random.h util.h -random.o: random.c random.h util.h +random.o: random.c random.h chacha.h util.h util.o: util.c util.h +chacha.o: chacha.c chacha.h clean: rm -f hardened_malloc.so $(OBJECTS) diff --git a/chacha.c b/chacha.c new file mode 100644 index 0000000..482b018 --- /dev/null +++ b/chacha.c @@ -0,0 +1,188 @@ +/* +Based on chacha-merged.c version 20080118 +D. J. Bernstein +Public domain. +*/ + +#include "chacha.h" + +#define U8C(v) (v##U) +#define U32C(v) (v##U) + +#define U8V(v) ((u8)(v) & U8C(0xFF)) +#define U32V(v) ((u32)(v) & U32C(0xFFFFFFFF)) + +#define ROTL32(v, n) \ + (U32V((v) << (n)) | ((v) >> (32 - (n)))) + +#define U8TO32_LITTLE(p) \ + (((u32)((p)[0]) ) | \ + ((u32)((p)[1]) << 8) | \ + ((u32)((p)[2]) << 16) | \ + ((u32)((p)[3]) << 24)) + +#define U32TO8_LITTLE(p, v) \ + do { \ + (p)[0] = U8V((v) ); \ + (p)[1] = U8V((v) >> 8); \ + (p)[2] = U8V((v) >> 16); \ + (p)[3] = U8V((v) >> 24); \ + } while (0) + +#define ROTATE(v,c) (ROTL32(v,c)) +#define XOR(v,w) ((v) ^ (w)) +#define PLUS(v,w) (U32V((v) + (w))) +#define PLUSONE(v) (PLUS((v),1)) + +#define QUARTERROUND(a,b,c,d) \ + a = PLUS(a,b); d = ROTATE(XOR(d,a),16); \ + c = PLUS(c,d); b = ROTATE(XOR(b,c),12); \ + a = PLUS(a,b); d = ROTATE(XOR(d,a), 8); \ + c = PLUS(c,d); b = ROTATE(XOR(b,c), 7); + +static const char sigma[16] = "expand 32-byte k"; +static const char tau[16] = "expand 16-byte k"; + +void chacha_keysetup(chacha_ctx *x,const u8 *k,u32 kbits) +{ + const char *constants; + + x->input[4] = U8TO32_LITTLE(k + 0); + x->input[5] = U8TO32_LITTLE(k + 4); + x->input[6] = U8TO32_LITTLE(k + 8); + x->input[7] = U8TO32_LITTLE(k + 12); + if (kbits == 256) { /* recommended */ + k += 16; + constants = sigma; + } else { /* kbits == 128 */ + constants = tau; + } + x->input[8] = U8TO32_LITTLE(k + 0); + x->input[9] = U8TO32_LITTLE(k + 4); + x->input[10] = U8TO32_LITTLE(k + 8); + x->input[11] = U8TO32_LITTLE(k + 12); + x->input[0] = U8TO32_LITTLE(constants + 0); + x->input[1] = U8TO32_LITTLE(constants + 4); + x->input[2] = U8TO32_LITTLE(constants + 8); + x->input[3] = U8TO32_LITTLE(constants + 12); +} + +void chacha_ivsetup(chacha_ctx *x,const u8 *iv) +{ + x->input[12] = 0; + x->input[13] = 0; + x->input[14] = U8TO32_LITTLE(iv + 0); + x->input[15] = U8TO32_LITTLE(iv + 4); +} + +void +chacha_keystream_bytes(chacha_ctx *x,u8 *c,u32 bytes) +{ + u32 x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15; + u32 j0, j1, j2, j3, j4, j5, j6, j7, j8, j9, j10, j11, j12, j13, j14, j15; + u8 *ctarget; + u8 tmp[64]; + unsigned i; + + if (!bytes) return; + + j0 = x->input[0]; + j1 = x->input[1]; + j2 = x->input[2]; + j3 = x->input[3]; + j4 = x->input[4]; + j5 = x->input[5]; + j6 = x->input[6]; + j7 = x->input[7]; + j8 = x->input[8]; + j9 = x->input[9]; + j10 = x->input[10]; + j11 = x->input[11]; + j12 = x->input[12]; + j13 = x->input[13]; + j14 = x->input[14]; + j15 = x->input[15]; + + for (;;) { + if (bytes < 64) { + ctarget = c; + c = tmp; + } + x0 = j0; + x1 = j1; + x2 = j2; + x3 = j3; + x4 = j4; + x5 = j5; + x6 = j6; + x7 = j7; + x8 = j8; + x9 = j9; + x10 = j10; + x11 = j11; + x12 = j12; + x13 = j13; + x14 = j14; + x15 = j15; + for (i = 8;i > 0;i -= 2) { + QUARTERROUND( x0, x4, x8,x12) + QUARTERROUND( x1, x5, x9,x13) + QUARTERROUND( x2, x6,x10,x14) + QUARTERROUND( x3, x7,x11,x15) + QUARTERROUND( x0, x5,x10,x15) + QUARTERROUND( x1, x6,x11,x12) + QUARTERROUND( x2, x7, x8,x13) + QUARTERROUND( x3, x4, x9,x14) + } + x0 = PLUS(x0,j0); + x1 = PLUS(x1,j1); + x2 = PLUS(x2,j2); + x3 = PLUS(x3,j3); + x4 = PLUS(x4,j4); + x5 = PLUS(x5,j5); + x6 = PLUS(x6,j6); + x7 = PLUS(x7,j7); + x8 = PLUS(x8,j8); + x9 = PLUS(x9,j9); + x10 = PLUS(x10,j10); + x11 = PLUS(x11,j11); + x12 = PLUS(x12,j12); + x13 = PLUS(x13,j13); + x14 = PLUS(x14,j14); + x15 = PLUS(x15,j15); + + j12 = PLUSONE(j12); + if (!j12) { + j13 = PLUSONE(j13); + /* stopping at 2^70 bytes per nonce is user's responsibility */ + } + + U32TO8_LITTLE(c + 0,x0); + U32TO8_LITTLE(c + 4,x1); + U32TO8_LITTLE(c + 8,x2); + U32TO8_LITTLE(c + 12,x3); + U32TO8_LITTLE(c + 16,x4); + U32TO8_LITTLE(c + 20,x5); + U32TO8_LITTLE(c + 24,x6); + U32TO8_LITTLE(c + 28,x7); + U32TO8_LITTLE(c + 32,x8); + U32TO8_LITTLE(c + 36,x9); + U32TO8_LITTLE(c + 40,x10); + U32TO8_LITTLE(c + 44,x11); + U32TO8_LITTLE(c + 48,x12); + U32TO8_LITTLE(c + 52,x13); + U32TO8_LITTLE(c + 56,x14); + U32TO8_LITTLE(c + 60,x15); + + if (bytes <= 64) { + if (bytes < 64) { + for (i = 0;i < bytes;++i) ctarget[i] = c[i]; + } + x->input[12] = j12; + x->input[13] = j13; + return; + } + bytes -= 64; + c += 64; + } +} diff --git a/chacha.h b/chacha.h new file mode 100644 index 0000000..1f0b551 --- /dev/null +++ b/chacha.h @@ -0,0 +1,18 @@ +#ifndef CHACHA_H +#define CHACHA_H + +#include + +typedef uint8_t u8; +typedef uint32_t u32; + +typedef struct +{ + u32 input[16]; +} chacha_ctx; + +void chacha_keysetup(chacha_ctx *x,const u8 *k,u32 kbits); +void chacha_ivsetup(chacha_ctx *x,const u8 *iv); +void chacha_keystream_bytes(chacha_ctx *x,u8 *c,u32 bytes); + +#endif diff --git a/random.c b/random.c index 9cee055..f04aef0 100644 --- a/random.c +++ b/random.c @@ -16,6 +16,8 @@ static ssize_t getrandom(void *buf, size_t buflen, unsigned int flags) { } #endif +#include "chacha.h" + static void get_random_seed(void *buf, size_t size) { while (size > 0) { ssize_t r; @@ -33,20 +35,34 @@ static void get_random_seed(void *buf, size_t size) { } } +#define KEY_SIZE 32 +#define IV_SIZE 8 + void random_state_init(struct random_state *state) { - state->index = RANDOM_CACHE_SIZE; + uint8_t rnd[KEY_SIZE + IV_SIZE]; + get_random_seed(rnd, sizeof(rnd)); + chacha_keysetup(&state->ctx, rnd, KEY_SIZE * 8); + chacha_ivsetup(&state->ctx, rnd + KEY_SIZE); + chacha_keystream_bytes(&state->ctx, state->cache, RANDOM_CACHE_SIZE); + state->index = 0; + state->reseed = 0; } void get_random_bytes(struct random_state *state, void *buf, size_t size) { if (size > RANDOM_CACHE_SIZE / 2) { - get_random_seed(buf, size); + chacha_keystream_bytes(&state->ctx, state->cache, RANDOM_CACHE_SIZE); return; } while (size) { if (state->index == RANDOM_CACHE_SIZE) { - state->index = 0; - get_random_seed(state->cache, RANDOM_CACHE_SIZE); + if (state->reseed >= RANDOM_RESEED_SIZE) { + random_state_init(state); + } else { + chacha_keystream_bytes(&state->ctx, state->cache, RANDOM_CACHE_SIZE); + state->index = 0; + state->reseed += RANDOM_CACHE_SIZE; + } } size_t remaining = RANDOM_CACHE_SIZE - state->index; size_t copy_size = size < remaining ? size : remaining; diff --git a/random.h b/random.h index 4568401..2174758 100644 --- a/random.h +++ b/random.h @@ -3,10 +3,15 @@ #include -#define RANDOM_CACHE_SIZE 4096 +#include "chacha.h" + +#define RANDOM_CACHE_SIZE 256ULL +#define RANDOM_RESEED_SIZE 256ULL * 1024 struct random_state { size_t index; + size_t reseed; + chacha_ctx ctx; uint8_t cache[RANDOM_CACHE_SIZE]; };