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/*
Authors:
Jan Cholasta <jcholast@redhat.com>
George McCollister <george.mccollister@gmail.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/>.
*/
#include "util/util.h"
#include "util/crypto/sss_crypto.h"
#include <openssl/evp.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;
EVP_MD_CTX ctx;
unsigned char ikey[HMAC_SHA1_BLOCKSIZE], okey[HMAC_SHA1_BLOCKSIZE];
size_t i;
unsigned char hash[SSS_SHA1_LENGTH];
unsigned int res_len;
EVP_MD_CTX_init(&ctx);
if (key_len > HMAC_SHA1_BLOCKSIZE) {
/* keys longer than blocksize are shortened */
if (!EVP_DigestInit_ex(&ctx, EVP_sha1(), NULL)) {
ret = EIO;
goto done;
}
EVP_DigestUpdate(&ctx, (const unsigned char *)key, key_len);
EVP_DigestFinal_ex(&ctx, ikey, &res_len);
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);
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;
}
if (!EVP_DigestInit_ex(&ctx, EVP_sha1(), NULL)) {
ret = EIO;
goto done;
}
EVP_DigestUpdate(&ctx, (const unsigned char *)ikey, HMAC_SHA1_BLOCKSIZE);
EVP_DigestUpdate(&ctx, (const unsigned char *)in, in_len);
EVP_DigestFinal_ex(&ctx, hash, &res_len);
if (!EVP_DigestInit_ex(&ctx, EVP_sha1(), NULL)) {
ret = EIO;
goto done;
}
EVP_DigestUpdate(&ctx, (const unsigned char *)okey, HMAC_SHA1_BLOCKSIZE);
EVP_DigestUpdate(&ctx, (const unsigned char *)hash, SSS_SHA1_LENGTH);
EVP_DigestFinal_ex(&ctx, out, &res_len);
ret = EOK;
done:
EVP_MD_CTX_cleanup(&ctx);
return ret;
}
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