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/*
* Copyright (c) 2017, Björn Esser <besser82@fedoraproject.org>
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
* OWNER 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.
*/
/*
* Implement HMAC as described in RFC 2104
*
*/
#include "crypt-port.h"
#include "alg-hmac-sha1.h"
#include "alg-sha1.h"
#include <stdlib.h>
#if INCLUDE_sha1crypt
/* Don't change these */
#define HMAC_IPAD 0x36
#define HMAC_OPAD 0x5c
/* Nor this */
#ifndef HMAC_BLOCKSZ
# define HMAC_BLOCKSZ 64
# define HASH_LENGTH 20
#endif
/*
* The logic here is lifted straight from RFC 2104 except that
* rather than filling the pads with 0, copying in the key and then
* XOR with the pad byte, we just fill with the pad byte and
* XOR with the key.
*/
void
hmac_sha1_process_data (const uint8_t *text, size_t text_len,
const uint8_t *key, size_t key_len,
void *resbuf)
{
struct sha1_ctx ctx;
/* Inner padding key XOR'd with ipad */
uint8_t k_ipad[HMAC_BLOCKSZ];
/* Outer padding key XOR'd with opad */
uint8_t k_opad[HMAC_BLOCKSZ];
/* HASH(key) if needed */
unsigned char tk[HASH_LENGTH];
size_t i;
/*
* If key is longer than HMAC_BLOCKSZ bytes
* reset it to key=HASH(key)
*/
if (key_len > HMAC_BLOCKSZ)
{
struct sha1_ctx tctx;
sha1_init_ctx (&tctx);
sha1_process_bytes (key, &tctx, key_len);
sha1_finish_ctx(&tctx, &tk);
key = tk;
key_len = HASH_LENGTH;
}
/*
* The HMAC_ transform looks like:
*
* HASH(K XOR opad, HASH(K XOR ipad, text))
*
* where K is an n byte key
* ipad is the byte HMAC_IPAD repeated HMAC_BLOCKSZ times
* opad is the byte HMAC_OPAD repeated HMAC_BLOCKSZ times
* and text is the data being protected
*/
/*
* Fill the pads and XOR in the key
*/
memset (k_ipad, HMAC_IPAD, sizeof k_ipad);
memset (k_opad, HMAC_OPAD, sizeof k_opad);
for (i = 0; i < key_len; i++)
{
k_ipad[i] ^= key[i];
k_opad[i] ^= key[i];
}
/*
* Perform inner HASH.
* Start with inner pad,
* then the text.
*/
sha1_init_ctx (&ctx);
sha1_process_bytes (k_ipad, &ctx, HMAC_BLOCKSZ);
sha1_process_bytes (text, &ctx, text_len);
sha1_finish_ctx(&ctx, resbuf);
/*
* Perform outer HASH.
* Start with the outer pad,
* then the result of the inner hash.
*/
sha1_init_ctx (&ctx);
sha1_process_bytes (k_opad, &ctx, HMAC_BLOCKSZ);
sha1_process_bytes (resbuf, &ctx, HASH_LENGTH);
sha1_finish_ctx(&ctx, resbuf);
}
#endif
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