/*
* hmac_sha1.c
*
* Version 1.0.0
*
* Written by Aaron D. Gifford <me@aarongifford.com>
*
* Copyright 1998, 2000 Aaron D. Gifford. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the copyright holder nor the names of contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR(S) OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* The HMAC-SHA256 has is defined as:
*
* HMAC = SHA256(K XOR opad, SHA256(K XOR ipad, message))
*
* "opad" is 64 bytes filled with 0x5c
* "ipad" is 64 bytes filled with 0x36
* "K" is the key material
*
* If the key material "K" is longer than 64 bytes, then the key material
* will first be digested (K = SHA1(K)) resulting in a 20-byte hash.
* If the key material is shorter than 64 bytes, it is padded with zero
* bytes.
*
* This code precomputes "K XOR ipad" and "K XOR opad" since that just makes
* sense.
*
* This code was heavily influenced by Eric A. Young's in how the interface
* was designed and how this file is formatted.
*/
#ifndef __HMAC_SHA256_H__
#define __HMAC_SHA256_H__
#include "hmac_sha256.h"
#include <string.h>
#ifdef __cplusplus
extern "C" {
#endif
/* Filler bytes: */
#define IPAD_BYTE 0x36
#define OPAD_BYTE 0x5c
#define ZERO_BYTE 0x00
void HMAC_SHA256_Init(HMAC_SHA256_CTX *ctx) {
memset(&(ctx->key[0]), ZERO_BYTE, HMAC_SHA256_BLOCK_LENGTH);
memset(&(ctx->ipad[0]), IPAD_BYTE, HMAC_SHA256_BLOCK_LENGTH);
memset(&(ctx->opad[0]), OPAD_BYTE, HMAC_SHA256_BLOCK_LENGTH);
ctx->keylen = 0;
ctx->hashkey = 0;
}
void HMAC_SHA256_UpdateKey(HMAC_SHA256_CTX *ctx, unsigned char *key, unsigned int keylen) {
/* Do we have anything to work with? If not, return right away. */
if (keylen < 1)
return;
/*
* Is the total key length (current data and any previous data)
* longer than the hash block length?
*/
if (ctx->hashkey !=0 || (keylen + ctx->keylen) > HMAC_SHA256_BLOCK_LENGTH) {
/*
* Looks like the key data exceeds the hash block length,
* so that means we use a hash of the key as the key data
* instead.
*/
if (ctx->hashkey == 0) {
/*
* Ah, we haven't started hashing the key
* data yet, so we must init. the hash
* monster to begin feeding it.
*/
/* Set the hash key flag to true (non-zero) */
ctx->hashkey = 1;
/* Init. the hash beastie... */
SHA256_Init(&ctx->shactx);
/* If there's any previous key data, use it */
if (ctx->keylen > 0) {
SHA256_Update(&ctx->shactx, &(ctx->key[0]), ctx->keylen);
}
/*
* Reset the key length to the future true
* key length, HMAC_SHA256_DIGEST_LENGTH
*/
ctx->keylen = HMAC_SHA256_DIGEST_LENGTH;
}
/* Now feed the latest key data to the has monster */
SHA256_Update(&ctx->shactx, key, keylen);
} else {
/*
* Key data length hasn't yet exceeded the hash
* block length (HMAC_SHA1_BLOCK_LENGTH), so theres
* no need to hash the key data (yet). Copy it
* into the key buffer.
*/
memcpy(&(ctx->key[ctx->keylen]), key, keylen);
ctx->keylen += keylen;
}
}
void HMAC_SHA256_EndKey(HMAC_SHA256_CTX *ctx) {
unsigned char *ipad, *opad, *key;
int i;
unsigned int j;
/* Did we end up hashing the key? */
if (ctx->hashkey) {
memset(&(ctx->key[0]), ZERO_BYTE, HMAC_SHA256_BLOCK_LENGTH);
/* Yes, so finish up and copy the key data */
SHA256_Final(&(ctx->key[0]), &ctx->shactx);
/* ctx->keylen was already set correctly */
}
/* Pad the key if necessary with zero bytes */
if ((i = HMAC_SHA256_BLOCK_LENGTH - ctx->keylen) > 0) {
memset(&(ctx->key[ctx->keylen]), ZERO_BYTE, i);
}
ipad = &(ctx->ipad[0]);
opad = &(ctx->opad[0]);
/* Precompute the respective pads XORed with the key */
key = &(ctx->key[0]);
for (j = 0; j < ctx->keylen; j++, key++) {
/* XOR the key byte with the appropriate pad filler byte */
*ipad++ ^= *key;
*opad++ ^= *key;
}
}
void HMAC_SHA256_StartMessage(HMAC_SHA256_CTX *ctx) {
SHA256_Init(&ctx->shactx);
SHA256_Update(&ctx->shactx, &(ctx->ipad[0]), HMAC_SHA256_BLOCK_LENGTH);
}
void HMAC_SHA256_UpdateMessage(HMAC_SHA256_CTX *ctx, unsigned char *data, unsigned int datalen) {
SHA256_Update(&ctx->shactx, data, datalen);
}
void HMAC_SHA256_EndMessage(unsigned char *out, HMAC_SHA256_CTX *ctx) {
unsigned char buf[HMAC_SHA256_DIGEST_LENGTH];
SHA256_CTX *c = &ctx->shactx;
SHA256_Final(&(buf[0]), c);
SHA256_Init(c);
SHA256_Update(c, &(ctx->opad[0]), HMAC_SHA256_BLOCK_LENGTH);
SHA256_Update(c, buf, HMAC_SHA256_DIGEST_LENGTH);
SHA256_Final(out, c);
}
void HMAC_SHA256_Done(HMAC_SHA256_CTX *ctx) {
/* Just to be safe, toast all context data */
memset(&(ctx->ipad[0]), ZERO_BYTE, HMAC_SHA256_BLOCK_LENGTH);
memset(&(ctx->ipad[0]), ZERO_BYTE, HMAC_SHA256_BLOCK_LENGTH);
memset(&(ctx->key[0]), ZERO_BYTE, HMAC_SHA256_BLOCK_LENGTH);
ctx->keylen = 0;
ctx->hashkey = 0;
}
#ifdef __cplusplus
}
#endif
#endif