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