3 This file is part of the AVR-Crypto-Lib.
4 Copyright (C) 2008 Daniel Otte (daniel.otte@rub.de)
6 This program is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
21 * implementation of HMAC as described in RFC2104
23 * email: daniel.otte@rub.de
24 * License: GPLv3 or later
28 * hmac = hash ( k^opad , hash( k^ipad , msg))
34 #include "sha256/sha256.h"
35 #include "hmac-sha256.h"
40 #ifndef HMAC_SHA256_SHORTONLY
42 void hmac_sha256_init(hmac_sha256_ctx_t *s, const void* key, uint16_t keylength_b){
43 uint8_t buffer[HMAC_SHA256_BLOCK_BYTES];
46 memset(buffer, 0, HMAC_SHA256_BLOCK_BYTES);
47 if (keylength_b > HMAC_SHA256_BLOCK_BITS){
48 sha256((void*)buffer, key, keylength_b);
50 memcpy(buffer, key, (keylength_b+7)/8);
53 for (i=0; i<HMAC_SHA256_BLOCK_BYTES; ++i){
58 sha256_nextBlock(&(s->a), buffer);
60 for (i=0; i<HMAC_SHA256_BLOCK_BYTES; ++i){
61 buffer[i] ^= IPAD^OPAD;
64 sha256_nextBlock(&(s->b), buffer);
66 #if defined SECURE_WIPE_BUFFER
67 memset(buffer, 0, SHA256_BLOCK_BYTES);
71 void hmac_sha256_nextBlock(hmac_sha256_ctx_t *s, const void* block){
72 sha256_nextBlock(&(s->a), block);
75 void hmac_sha256_lastBlock(hmac_sha256_ctx_t *s, const void* block, uint16_t length_b){
76 /* while(length_b>=SHA256_BLOCK_BITS){
77 sha256_nextBlock(&(s->a), block);
78 block = (uint8_t*)block + SHA256_BLOCK_BYTES;
79 length_b -= SHA256_BLOCK_BITS;
81 */ sha256_lastBlock(&(s->a), block, length_b);
84 void hmac_sha256_final(void* dest, hmac_sha256_ctx_t *s){
85 sha256_ctx2hash((sha256_hash_t*)dest, &(s->a));
86 sha256_lastBlock(&(s->b), dest, SHA256_HASH_BITS);
87 sha256_ctx2hash((sha256_hash_t*)dest, &(s->b));
94 * message length in bits!
96 void hmac_sha256(void* dest, const void* key, uint16_t keylength_b, const void* msg, uint32_t msglength_b){ /* a one-shot*/
99 uint8_t buffer[HMAC_SHA256_BLOCK_BYTES];
101 memset(buffer, 0, HMAC_SHA256_BLOCK_BYTES);
103 /* if key is larger than a block we have to hash it*/
104 if (keylength_b > SHA256_BLOCK_BITS){
105 sha256((void*)buffer, key, keylength_b);
107 memcpy(buffer, key, (keylength_b+7)/8);
110 for (i=0; i<SHA256_BLOCK_BYTES; ++i){
114 sha256_nextBlock(&s, buffer);
115 while (msglength_b >= HMAC_SHA256_BLOCK_BITS){
116 sha256_nextBlock(&s, msg);
117 msg = (uint8_t*)msg + HMAC_SHA256_BLOCK_BYTES;
118 msglength_b -= HMAC_SHA256_BLOCK_BITS;
120 sha256_lastBlock(&s, msg, msglength_b);
121 /* since buffer still contains key xor ipad we can do ... */
122 for (i=0; i<HMAC_SHA256_BLOCK_BYTES; ++i){
123 buffer[i] ^= IPAD ^ OPAD;
125 sha256_ctx2hash(dest, &s); /* save inner hash temporary to dest */
127 sha256_nextBlock(&s, buffer);
128 sha256_lastBlock(&s, dest, SHA256_HASH_BITS);
129 sha256_ctx2hash(dest, &s);