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/*
* librest - RESTful web services access
* Copyright (c) 2008, 2009, Intel Corporation.
*
* Authors: Ross Burton <ross@linux.intel.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU Lesser General Public License,
* version 2.1, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
* more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
*
*/
#include <string.h>
#include <glib.h>
#include "sha1.h"
#define SHA1_BLOCK_SIZE 64
#define SHA1_LENGTH 20
/*
* hmac_sha1:
* @key: The key
* @message: The message
*
* Given the key and message, compute the HMAC-SHA1 hash and return the base-64
* encoding of it. This is very geared towards OAuth, and as such both key and
* message must be NULL-terminated strings, and the result is base-64 encoded.
*/
char *
hmac_sha1 (const char *key, const char *message)
{
GChecksum *checksum;
char *real_key;
guchar ipad[SHA1_BLOCK_SIZE];
guchar opad[SHA1_BLOCK_SIZE];
guchar inner[SHA1_LENGTH];
guchar digest[SHA1_LENGTH];
gsize key_length, inner_length, digest_length;
int i;
g_return_val_if_fail (key, NULL);
g_return_val_if_fail (message, NULL);
checksum = g_checksum_new (G_CHECKSUM_SHA1);
/* If the key is longer than the block size, hash it first */
if (strlen (key) > SHA1_BLOCK_SIZE) {
guchar new_key[SHA1_LENGTH];
key_length = sizeof (new_key);
g_checksum_update (checksum, (guchar*)key, strlen (key));
g_checksum_get_digest (checksum, new_key, &key_length);
g_checksum_reset (checksum);
real_key = g_memdup (new_key, key_length);
} else {
real_key = g_strdup (key);
key_length = strlen (key);
}
/* Sanity check the length */
g_assert (key_length <= SHA1_BLOCK_SIZE);
/* Protect against use of the provided key by NULLing it */
key = NULL;
/* Stage 1 */
memset (ipad, 0, sizeof (ipad));
memset (opad, 0, sizeof (opad));
memcpy (ipad, real_key, key_length);
memcpy (opad, real_key, key_length);
/* Stage 2 and 5 */
for (i = 0; i < sizeof (ipad); i++) {
ipad[i] ^= 0x36;
opad[i] ^= 0x5C;
}
/* Stage 3 and 4 */
g_checksum_update (checksum, ipad, sizeof (ipad));
g_checksum_update (checksum, (guchar*)message, strlen (message));
inner_length = sizeof (inner);
g_checksum_get_digest (checksum, inner, &inner_length);
g_checksum_reset (checksum);
/* Stage 6 and 7 */
g_checksum_update (checksum, opad, sizeof (opad));
g_checksum_update (checksum, inner, inner_length);
digest_length = sizeof (digest);
g_checksum_get_digest (checksum, digest, &digest_length);
g_checksum_free (checksum);
g_free (real_key);
return g_base64_encode (digest, digest_length);
}
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