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tls: simplify aesgcm_GHASH()

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function                                             old     new   delta
xwrite_encrypted                                     604     599      -5
FlattenSzInBits                                       52       -     -52
aesgcm_GHASH                                         395     262    -133
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 0/2 up/down: 0/-190)           Total: -190 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
2018-11-23 18:31:26 +01:00
parent 5e4236d226
commit ecc9090cfc
3 changed files with 60 additions and 47 deletions
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73
networking/tls_aesgcm.c
View File

@@ -25,23 +25,26 @@ void FAST_FUNC xorbuf(void* buf, const void* mask, unsigned count)
b[i] ^= m[i];
}
/* wolfssl-3.15.3/wolfcrypt/src/aes.c */
/* from wolfssl-3.15.3/wolfcrypt/src/aes.c */
static void FlattenSzInBits(byte* buf, word32 sz)
static ALWAYS_INLINE void FlattenSzInBits(byte* buf, word32 sz)
{
/* Multiply the sz by 8 */
word32 szHi = (sz >> (8*sizeof(sz) - 3));
//bbox: these sizes are never even close to 2^32/8
// word32 szHi = (sz >> (8*sizeof(sz) - 3));
sz <<= 3;
/* copy over the words of the sz into the destination buffer */
buf[0] = (szHi >> 24) & 0xff;
buf[1] = (szHi >> 16) & 0xff;
buf[2] = (szHi >> 8) & 0xff;
buf[3] = szHi & 0xff;
buf[4] = (sz >> 24) & 0xff;
buf[5] = (sz >> 16) & 0xff;
buf[6] = (sz >> 8) & 0xff;
buf[7] = sz & 0xff;
// buf[0] = (szHi >> 24) & 0xff;
// buf[1] = (szHi >> 16) & 0xff;
// buf[2] = (szHi >> 8) & 0xff;
// buf[3] = szHi & 0xff;
move_to_unaligned32(buf, 0);
// buf[4] = (sz >> 24) & 0xff;
// buf[5] = (sz >> 16) & 0xff;
// buf[6] = (sz >> 8) & 0xff;
// buf[7] = sz & 0xff;
move_to_unaligned32(buf + 4, SWAP_BE32(sz));
}
static void RIGHTSHIFTX(byte* x)
@@ -83,35 +86,47 @@ static void GMULT(byte* X, byte* Y)
XMEMCPY(X, Z, AES_BLOCK_SIZE);
}
void FAST_FUNC aesgcm_GHASH(byte* h, const byte* a, unsigned aSz, const byte* c,
unsigned cSz, byte* s, unsigned sSz)
//bbox:
// for TLS AES-GCM, a (which as AAD) is always 13 bytes long, and bbox code provides
// extra 3 zeroed bytes, making it a[16], or a[AES_BLOCK_SIZE].
// Resulting auth tag in s is also always AES_BLOCK_SIZE bytes.
//
// This allows some simplifications.
#define aSz AES_BLOCK_SIZE
#define sSz AES_BLOCK_SIZE
void FAST_FUNC aesgcm_GHASH(byte* h,
const byte* a, //unsigned aSz,
const byte* c, unsigned cSz,
byte* s //, unsigned sSz
)
{
byte x[AES_BLOCK_SIZE];
byte scratch[AES_BLOCK_SIZE];
word32 blocks, partial;
//was: byte* h = aes->H;
XMEMSET(x, 0, AES_BLOCK_SIZE);
//XMEMSET(x, 0, AES_BLOCK_SIZE);
/* Hash in A, the Additional Authentication Data */
if (aSz != 0 && a != NULL) {
blocks = aSz / AES_BLOCK_SIZE;
partial = aSz % AES_BLOCK_SIZE;
while (blocks--) {
xorbuf(x, a, AES_BLOCK_SIZE);
// if (aSz != 0 && a != NULL) {
// blocks = aSz / AES_BLOCK_SIZE;
// partial = aSz % AES_BLOCK_SIZE;
// while (blocks--) {
//xorbuf(x, a, AES_BLOCK_SIZE);
XMEMCPY(x, a, AES_BLOCK_SIZE);// memcpy(x,a) = memset(x,0)+xorbuf(x,a)
GMULT(x, h);
a += AES_BLOCK_SIZE;
}
if (partial != 0) {
XMEMSET(scratch, 0, AES_BLOCK_SIZE);
XMEMCPY(scratch, a, partial);
xorbuf(x, scratch, AES_BLOCK_SIZE);
GMULT(x, h);
}
}
// a += AES_BLOCK_SIZE;
// }
// if (partial != 0) {
// XMEMSET(scratch, 0, AES_BLOCK_SIZE);
// XMEMCPY(scratch, a, partial);
// xorbuf(x, scratch, AES_BLOCK_SIZE);
// GMULT(x, h);
// }
// }
/* Hash in C, the Ciphertext */
if (cSz != 0 && c != NULL) {
if (cSz != 0 /*&& c != NULL*/) {
blocks = cSz / AES_BLOCK_SIZE;
partial = cSz % AES_BLOCK_SIZE;
while (blocks--) {