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hmac.c
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hmac.c
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//
// hmac.c
// OAuthConsumer
//
// Created by Jonathan Wight on 4/8/8.
// Copyright 2008 Jonathan Wight. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
/*
* Implementation of HMAC-SHA1. Adapted from example at http://tools.ietf.org/html/rfc2104
*/
#include "sha1.h"
#include <stdlib.h>
#include <string.h>
void hmac_sha1(const unsigned char *inText, size_t inTextLength, unsigned char* inKey, size_t inKeyLength, unsigned char *outDigest)
{
const size_t B = 64;
const size_t L = 20;
SHA1_CTX theSHA1Context;
unsigned char k_ipad[B + 1]; /* inner padding - key XORd with ipad */
unsigned char k_opad[B + 1]; /* outer padding - key XORd with opad */
/* if key is longer than 64 bytes reset it to key=SHA1 (key) */
if (inKeyLength > B)
{
SHA1Init(&theSHA1Context);
SHA1Update(&theSHA1Context, inKey, inKeyLength);
SHA1Final(inKey, &theSHA1Context);
inKeyLength = L;
}
/* start out by storing key in pads */
memset(k_ipad, 0, sizeof k_ipad);
memset(k_opad, 0, sizeof k_opad);
memcpy(k_ipad, inKey, inKeyLength);
memcpy(k_opad, inKey, inKeyLength);
/* XOR key with ipad and opad values */
int i;
for (i = 0; i < B; i++)
{
k_ipad[i] ^= 0x36;
k_opad[i] ^= 0x5c;
}
/*
* perform inner SHA1
*/
SHA1Init(&theSHA1Context); /* init context for 1st pass */
SHA1Update(&theSHA1Context, k_ipad, B); /* start with inner pad */
SHA1Update(&theSHA1Context, (unsigned char *)inText, inTextLength); /* then text of datagram */
SHA1Final((unsigned char *)outDigest, &theSHA1Context); /* finish up 1st pass */
/*
* perform outer SHA1
*/
SHA1Init(&theSHA1Context); /* init context for 2nd
* pass */
SHA1Update(&theSHA1Context, k_opad, B); /* start with outer pad */
SHA1Update(&theSHA1Context, outDigest, L); /* then results of 1st
* hash */
SHA1Final(outDigest, &theSHA1Context); /* finish up 2nd pass */
}