131 lines
3.5 KiB
C
131 lines
3.5 KiB
C
/* hmac-sha256.c */
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/*
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This file is part of the AVR-Crypto-Lib.
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Copyright (C) 2006-2015 Daniel Otte (bg@nerilex.org)
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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*
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* implementation of HMAC as described in RFC2104
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* Author: Daniel Otte
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* email: bg@nerilex.org
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* License: GPLv3 or later
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**/
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/*
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* hmac = hash ( k^opad , hash( k^ipad , msg))
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*/
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#include <stdint.h>
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#include <string.h>
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#include "config.h"
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#include "sha256.h"
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#include "hmac-sha256.h"
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#define IPAD 0x36
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#define OPAD 0x5C
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#ifndef HMAC_SHA256_SHORTONLY
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void hmac_sha256_init(hmac_sha256_ctx_t *s, const void *key, uint16_t keylength_b){
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uint8_t buffer[HMAC_SHA256_BLOCK_BYTES];
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uint8_t i;
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memset(buffer, 0, HMAC_SHA256_BLOCK_BYTES);
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if (keylength_b > HMAC_SHA256_BLOCK_BITS){
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sha256((void*)buffer, key, keylength_b);
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} else {
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memcpy(buffer, key, (keylength_b+7)/8);
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}
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for (i=0; i<HMAC_SHA256_BLOCK_BYTES; ++i){
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buffer[i] ^= IPAD;
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}
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sha256_init(&(s->a));
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sha256_nextBlock(&(s->a), buffer);
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for (i=0; i<HMAC_SHA256_BLOCK_BYTES; ++i){
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buffer[i] ^= IPAD^OPAD;
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}
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sha256_init(&(s->b));
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sha256_nextBlock(&(s->b), buffer);
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#if defined SECURE_WIPE_BUFFER
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memset(buffer, 0, SHA256_BLOCK_BYTES);
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#endif
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}
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void hmac_sha256_nextBlock(hmac_sha256_ctx_t *s, const void *block){
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sha256_nextBlock(&(s->a), block);
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}
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void hmac_sha256_lastBlock(hmac_sha256_ctx_t *s, const void *block, uint16_t length_b){
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/* while(length_b>=SHA256_BLOCK_BITS){
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sha256_nextBlock(&(s->a), block);
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block = (uint8_t*)block + SHA256_BLOCK_BYTES;
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length_b -= SHA256_BLOCK_BITS;
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}
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*/ sha256_lastBlock(&(s->a), block, length_b);
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}
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void hmac_sha256_final(void *dest, hmac_sha256_ctx_t *s){
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sha256_ctx2hash((sha256_hash_t*)dest, &(s->a));
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sha256_lastBlock(&(s->b), dest, SHA256_HASH_BITS);
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sha256_ctx2hash((sha256_hash_t*)dest, &(s->b));
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}
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#endif
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/*
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* keylength in bits!
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* message length in bits!
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*/
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void hmac_sha256(void *dest, const void *key, uint16_t keylength_b, const void *msg, uint32_t msglength_b){ /* a one-shot*/
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sha256_ctx_t s;
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uint8_t i;
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uint8_t buffer[HMAC_SHA256_BLOCK_BYTES];
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memset(buffer, 0, HMAC_SHA256_BLOCK_BYTES);
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/* if key is larger than a block we have to hash it*/
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if (keylength_b > SHA256_BLOCK_BITS){
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sha256((void*)buffer, key, keylength_b);
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} else {
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memcpy(buffer, key, (keylength_b+7)/8);
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}
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for (i=0; i<SHA256_BLOCK_BYTES; ++i){
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buffer[i] ^= IPAD;
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}
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sha256_init(&s);
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sha256_nextBlock(&s, buffer);
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while (msglength_b >= HMAC_SHA256_BLOCK_BITS){
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sha256_nextBlock(&s, msg);
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msg = (uint8_t*)msg + HMAC_SHA256_BLOCK_BYTES;
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msglength_b -= HMAC_SHA256_BLOCK_BITS;
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}
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sha256_lastBlock(&s, msg, msglength_b);
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/* since buffer still contains key xor ipad we can do ... */
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for (i=0; i<HMAC_SHA256_BLOCK_BYTES; ++i){
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buffer[i] ^= IPAD ^ OPAD;
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}
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sha256_ctx2hash(dest, &s); /* save inner hash temporary to dest */
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sha256_init(&s);
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sha256_nextBlock(&s, buffer);
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sha256_lastBlock(&s, dest, SHA256_HASH_BITS);
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sha256_ctx2hash(dest, &s);
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}
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