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/*
Authors:
Jan Cholasta <jcholast@redhat.com>
Copyright (C) 2012 Red Hat
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
NSS does not provide public API for HMAC, so we implement it ourselves.
See RFC 2104 for details on the algorithm.
*/
#include "util/util.h"
#include "util/crypto/sss_crypto.h"
#include "util/crypto/nss/nss_util.h"
#include <sechash.h>
#define HMAC_SHA1_BLOCKSIZE 64
int sss_hmac_sha1(const unsigned char *key,
size_t key_len,
const unsigned char *in,
size_t in_len,
unsigned char *out)
{
int ret;
unsigned char ikey[HMAC_SHA1_BLOCKSIZE], okey[HMAC_SHA1_BLOCKSIZE];
size_t i;
HASHContext *sha1;
unsigned char hash[SSS_SHA1_LENGTH];
unsigned int res_len;
ret = nspr_nss_init();
if (ret != EOK) {
return ret;
}
sha1 = HASH_Create(HASH_AlgSHA1);
if (!sha1) {
return ENOMEM;
}
if (key_len > HMAC_SHA1_BLOCKSIZE) {
/* keys longer than blocksize are shortened */
HASH_Begin(sha1);
HASH_Update(sha1, key, key_len);
HASH_End(sha1, ikey, &res_len, SSS_SHA1_LENGTH);
memset(ikey + SSS_SHA1_LENGTH, 0, HMAC_SHA1_BLOCKSIZE - SSS_SHA1_LENGTH);
} else {
/* keys shorter than blocksize are zero-padded */
memcpy(ikey, key, key_len);
if (key_len != HMAC_SHA1_BLOCKSIZE) {
memset(ikey + key_len, 0, HMAC_SHA1_BLOCKSIZE - key_len);
}
}
/* HMAC(key, msg) = HASH(key XOR opad, HASH(key XOR ipad, msg)) */
for (i = 0; i < HMAC_SHA1_BLOCKSIZE; i++) {
okey[i] = ikey[i] ^ 0x5c;
ikey[i] ^= 0x36;
}
HASH_Begin(sha1);
HASH_Update(sha1, ikey, HMAC_SHA1_BLOCKSIZE);
HASH_Update(sha1, in, in_len);
HASH_End(sha1, hash, &res_len, SSS_SHA1_LENGTH);
HASH_Begin(sha1);
HASH_Update(sha1, okey, HMAC_SHA1_BLOCKSIZE);
HASH_Update(sha1, hash, SSS_SHA1_LENGTH);
HASH_End(sha1, out, &res_len, SSS_SHA1_LENGTH);
HASH_Destroy(sha1);
return EOK;
}
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