cryb-to/lib/mac/hmac.c
2014-07-10 17:15:54 +00:00

110 lines
3.2 KiB
C

/*-
* Copyright (c) 2012 The University of Oslo
* Copyright (c) 2012 Dag-Erling Smørgrav
* 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. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 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.
*
* Author: Dag-Erling Smørgrav <des@des.no>
* Sponsor: the University of Oslo
*
* $Cryb$
*/
#include "cryb/impl.h"
#ifdef HAVE_SYS_ENDIAN_H
#include <sys/endian.h>
#endif
#ifdef HAVE_ENDIAN_H
#define _BSD_SOURCE
#include <endian.h>
#endif
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <cryb/sha1.h>
#include <cryb/hmac.h>
void
hmac_init(struct hmac_ctx *ctx, const uint8_t *key, size_t keylen)
{
uint8_t ipad[64];
memset(ctx, 0, sizeof *ctx);
#if 1
if (keylen > sizeof ctx->key)
sha1_complete(key, keylen, ctx->key);
else
memcpy(ctx->key, key, keylen);
#else
uint8_t keybuf[sizeof ctx->key] = { 0 };
sha1_complete(key, keylen, keybuf);
if (keylen > sizeof ctx->key)
memcpy(ctx->key, keybuf, SHA1_DIGEST_LEN);
else
memcpy(ctx->key, key, keylen);
#endif
sha1_init(&ctx->sha1_ctx);
for (unsigned int i = 0; i < sizeof ipad; ++i)
ipad[i] = 0x36 ^ ctx->key[i];
sha1_update(&ctx->sha1_ctx, ipad, sizeof ipad);
}
void
hmac_update(struct hmac_ctx *ctx, const uint8_t *buf, size_t len)
{
sha1_update(&ctx->sha1_ctx, buf, len);
}
void
hmac_final(struct hmac_ctx *ctx, uint8_t *mac)
{
uint8_t digest[20], opad[64];
sha1_final(&ctx->sha1_ctx, digest);
for (unsigned int i = 0; i < sizeof opad; ++i)
opad[i] = 0x5c ^ ctx->key[i];
sha1_init(&ctx->sha1_ctx);
sha1_update(&ctx->sha1_ctx, opad, sizeof opad);
sha1_update(&ctx->sha1_ctx, digest, sizeof digest);
sha1_final(&ctx->sha1_ctx, mac);
memset(ctx, 0, sizeof *ctx);
}
void
hmac_complete(const uint8_t *key, size_t keylen,
const uint8_t *buf, size_t len, uint8_t *mac)
{
struct hmac_ctx ctx;
hmac_init(&ctx, key, keylen);
hmac_update(&ctx, buf, len);
hmac_final(&ctx, mac);
}