diff options
Diffstat (limited to 'cmac.c')
| -rw-r--r-- | cmac.c | 41 |
1 files changed, 21 insertions, 20 deletions
@@ -70,21 +70,24 @@ block_mulx(union nettle_block16 *dst, #endif /* !WORDS_BIGENDIAN */ void -cmac128_set_key(struct cmac128_ctx *ctx, const void *cipher, +cmac128_set_key(struct cmac128_key *key, const void *cipher, nettle_cipher_func *encrypt) { - static const uint8_t const_zero[] = { - 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, - 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 - }; - union nettle_block16 *L = &ctx->block; - memset(ctx, 0, sizeof(*ctx)); + static const union nettle_block16 zero_block; + union nettle_block16 L; /* step 1 - generate subkeys k1 and k2 */ - encrypt(cipher, 16, L->b, const_zero); + encrypt(cipher, 16, L.b, zero_block.b); - block_mulx(&ctx->key.K1, L); - block_mulx(&ctx->key.K2, &ctx->key.K1); + block_mulx(&key->K1, &L); + block_mulx(&key->K2, &key->K1); +} + +void +cmac128_init(struct cmac128_ctx *ctx) +{ + memset(&ctx->X, 0, sizeof(ctx->X)); + ctx->index = 0; } #define MIN(x,y) ((x)<(y)?(x):(y)) @@ -135,24 +138,23 @@ cmac128_update(struct cmac128_ctx *ctx, const void *cipher, } void -cmac128_digest(struct cmac128_ctx *ctx, const void *cipher, - nettle_cipher_func *encrypt, - unsigned length, - uint8_t *dst) +cmac128_digest(struct cmac128_ctx *ctx, const struct cmac128_key *key, + const void *cipher, nettle_cipher_func *encrypt, + unsigned length, uint8_t *dst) { union nettle_block16 Y; - memset(ctx->block.b+ctx->index, 0, sizeof(ctx->block.b)-ctx->index); - /* re-use ctx->block for memxor output */ if (ctx->index < 16) { ctx->block.b[ctx->index] = 0x80; - memxor(ctx->block.b, ctx->key.K2.b, 16); + memset(ctx->block.b + ctx->index + 1, 0, 16 - 1 - ctx->index); + + memxor(ctx->block.b, key->K2.b, 16); } else { - memxor(ctx->block.b, ctx->key.K1.b, 16); + memxor(ctx->block.b, key->K1.b, 16); } memxor3(Y.b, ctx->block.b, ctx->X.b, 16); @@ -169,6 +171,5 @@ cmac128_digest(struct cmac128_ctx *ctx, const void *cipher, } /* reset state for re-use */ - memset(&ctx->X, 0, sizeof(ctx->X)); - ctx->index = 0; + cmac128_init(ctx); } |