From: Denys Vlasenko Date: Fri, 23 Nov 2018 17:31:26 +0000 (+0100) Subject: tls: simplify aesgcm_GHASH() X-Git-Tag: 1_30_0~387 X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=ecc9090cfcccf412288147f385808f8f9df97ebe;p=oweals%2Fbusybox.git tls: simplify aesgcm_GHASH() 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 --- diff --git a/networking/tls.c b/networking/tls.c index 23622d76e..3b4f1b7e2 100644 --- a/networking/tls.c +++ b/networking/tls.c @@ -270,7 +270,7 @@ struct record_hdr { enum { NEED_EC_KEY = 1 << 0, GOT_CERT_RSA_KEY_ALG = 1 << 1, - GOT_CERT_ECDSA_KEY_ALG = 1 << 2, + GOT_CERT_ECDSA_KEY_ALG = 1 << 2, GOT_EC_KEY = 1 << 3, ENCRYPTION_AESGCM = 1 << 4, }; @@ -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)); diff --git a/networking/tls_aesgcm.c b/networking/tls_aesgcm.c index eb32f4c05..1a7ddb2e2 100644 --- a/networking/tls_aesgcm.c +++ b/networking/tls_aesgcm.c @@ -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); - 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); +// 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); +// } +// } /* 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--) { diff --git a/networking/tls_aesgcm.h b/networking/tls_aesgcm.h index a71eced54..75694f3fa 100644 --- a/networking/tls_aesgcm.h +++ b/networking/tls_aesgcm.h @@ -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;