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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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
networking/tls.c
View File

@ -756,7 +756,6 @@ static void xwrite_encrypted_and_hmac_signed(tls_state_t *tls, unsigned size, un
} while ((size & (AES_BLOCK_SIZE - 1)) != 0);
/* Encrypt content+MAC+padding in place */
//optimize key setup
aes_cbc_encrypt(
&tls->aes_decrypt, /* selects 128/256 */
buf - AES_BLOCK_SIZE, /* IV */
@ -787,8 +786,9 @@ static void xwrite_encrypted_and_hmac_signed(tls_state_t *tls, unsigned size, un
*/
static void xwrite_encrypted_aesgcm(tls_state_t *tls, unsigned size, unsigned type)
{
//go for [16]
uint8_t aad[13];
#define COUNTER(v) (*(uint32_t*)(v + 12))
uint8_t aad[13 + 3]; /* +3 creates [16] buffer, simplifying GHASH() */
uint8_t nonce[12 + 4]; /* +4 creates space for AES block counter */
uint8_t scratch[AES_BLOCK_SIZE]; //[16]
uint8_t authtag[AES_BLOCK_SIZE]; //[16]
@ -807,7 +807,8 @@ static void xwrite_encrypted_aesgcm(tls_state_t *tls, unsigned size, unsigned ty
aad[9] = TLS_MAJ;
aad[10] = TLS_MIN;
aad[11] = size >> 8;
aad[12] = size & 0xff;
/* set aad[12], and clear aad[13..15] */
COUNTER(aad) = SWAP_LE32(size & 0xff);
memcpy(nonce, tls->client_write_IV, 4);
memcpy(nonce + 4, &tls->write_seq64_be, 8);
@ -817,8 +818,6 @@ static void xwrite_encrypted_aesgcm(tls_state_t *tls, unsigned size, unsigned ty
/* seq64 is not used later in this func, can increment here */
tls->write_seq64_be = SWAP_BE64(1 + SWAP_BE64(tls->write_seq64_be));
#define COUNTER(v) (*(uint32_t*)(v + 12))
cnt = 1;
remaining = size;
while (remaining != 0) {
@ -833,8 +832,7 @@ static void xwrite_encrypted_aesgcm(tls_state_t *tls, unsigned size, unsigned ty
remaining -= n;
}
//optimize fixed sizes
aesgcm_GHASH(tls->H, aad, sizeof(aad), tls->outbuf + OUTBUF_PFX, size, authtag, sizeof(authtag));
aesgcm_GHASH(tls->H, aad, /*sizeof(aad),*/ tls->outbuf + OUTBUF_PFX, size, authtag /*, sizeof(authtag)*/);
COUNTER(nonce) = htonl(1);
aes_encrypt_one_block(&tls->aes_encrypt, nonce, scratch);
xorbuf(authtag, scratch, sizeof(authtag));
@ -923,8 +921,9 @@ static const char *alert_text(int code)
static void tls_aesgcm_decrypt(tls_state_t *tls, uint8_t *buf, int size)
{
//go for [16]
//uint8_t aad[13];
#define COUNTER(v) (*(uint32_t*)(v + 12))
//uint8_t aad[13 + 3]; /* +3 creates [16] buffer, simplifying GHASH() */
uint8_t nonce[12 + 4]; /* +4 creates space for AES block counter */
uint8_t scratch[AES_BLOCK_SIZE]; //[16]
//uint8_t authtag[AES_BLOCK_SIZE]; //[16]
@ -935,14 +934,14 @@ static void tls_aesgcm_decrypt(tls_state_t *tls, uint8_t *buf, int size)
//aad[9] = TLS_MAJ;
//aad[10] = TLS_MIN;
//aad[11] = size >> 8;
//aad[12] = size & 0xff;
///* set aad[12], and clear aad[13..15] */
//COUNTER(aad) = SWAP_LE32(size & 0xff);
//memcpy(aad, &tls->write_seq64_be, 8);
memcpy(nonce, tls->server_write_IV, 4);
memcpy(nonce + 4, buf, 8);
buf += 8;
#define COUNTER(v) (*(uint32_t*)(v + 12))
cnt = 1;
remaining = size;
while (remaining != 0) {
@ -957,8 +956,7 @@ static void tls_aesgcm_decrypt(tls_state_t *tls, uint8_t *buf, int size)
remaining -= n;
}
////optimize fixed sizes
//aesgcm_GHASH(tls->H, aad, sizeof(aad), tls->outbuf + OUTBUF_PFX, size, authtag, sizeof(authtag));
//aesgcm_GHASH(tls->H, aad, tls->outbuf + OUTBUF_PFX, size, authtag);
//COUNTER(nonce) = htonl(1);
//aes_encrypt_one_block(&tls->aes_encrypt, nonce, scratch);
//xorbuf(authtag, scratch, sizeof(authtag));

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--) {

4
networking/tls_aesgcm.h
View File

@ -7,7 +7,7 @@
void xorbuf(void* buf, const void* mask, unsigned count) FAST_FUNC;
void aesgcm_GHASH(uint8_t* h,
const uint8_t* a, unsigned aSz,
const uint8_t* a, //unsigned aSz,
const uint8_t* c, unsigned cSz,
uint8_t* s, unsigned sSz
uint8_t* s //, unsigned sSz
) FAST_FUNC;