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/*
* Copyright (C) 2017 Red Hat, Inc.
*
* Author: Nikos Mavrogiannopoulos
*
* This file is part of GnuTLS.
*
* The GnuTLS is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This library 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
* 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, see <https://www.gnu.org/licenses/>
*
*/
/* Functions for the TLS PRF handling.
*/
#if HAVE_CONFIG_H
# include <config.h>
#endif
#include <gnutls_int.h>
#include <stdlib.h>
#include <string.h>
#include <nettle/hmac.h>
#include <nettle/memxor.h>
#include "int/tls1-prf.h"
#include <nettle/sha1.h>
#include <nettle/md5.h>
/* The RFC2246 P_hash() function. The mac_ctx is expected to
* be initialized and key set to be the secret key.
*/
static void
P_hash( void *mac_ctx,
nettle_hash_update_func *update,
nettle_hash_digest_func *digest,
size_t digest_size,
size_t seed_size, const uint8_t *seed,
size_t dst_length,
uint8_t *dst)
{
uint8_t Atmp[MAX_HASH_SIZE];
ssize_t left;
unsigned started = 0;
/* round up */
left = dst_length;
while(left > 0) {
if (started == 0) { /* A(0) */
update(mac_ctx, seed_size, seed);
started = 1;
} else {
update(mac_ctx, digest_size, Atmp);
}
digest(mac_ctx, digest_size, Atmp); /* store A(i) */
update(mac_ctx, digest_size, Atmp); /* hash A(i) */
update(mac_ctx, seed_size, seed); /* hash seed */
if (left < (ssize_t)digest_size)
digest_size = left;
digest(mac_ctx, digest_size, dst);
left -= digest_size;
dst += digest_size;
}
return;
}
int
tls10_prf(size_t secret_size, const uint8_t *secret,
size_t label_size, const char *label,
size_t seed_size, const uint8_t *seed,
size_t length, uint8_t *dst)
{
int l_s, cseed_size = seed_size + label_size;
const uint8_t *s1, *s2;
struct hmac_md5_ctx md5_ctx;
struct hmac_sha1_ctx sha1_ctx;
uint8_t o1[MAX_PRF_BYTES];
uint8_t cseed[MAX_SEED_SIZE];
if (cseed_size > MAX_SEED_SIZE || length > MAX_PRF_BYTES)
return 0;
memcpy(cseed, label, label_size);
memcpy(&cseed[label_size], seed, seed_size);
l_s = secret_size / 2;
s1 = &secret[0];
s2 = &secret[l_s];
if (secret_size % 2 != 0) {
l_s++;
}
hmac_md5_set_key(&md5_ctx, l_s, s1);
P_hash(&md5_ctx, (nettle_hash_update_func*)hmac_md5_update,
(nettle_hash_digest_func*)hmac_md5_digest,
MD5_DIGEST_SIZE,
cseed_size, cseed, length, o1);
hmac_sha1_set_key(&sha1_ctx, l_s, s2);
P_hash(&sha1_ctx, (nettle_hash_update_func*)hmac_sha1_update,
(nettle_hash_digest_func*)hmac_sha1_digest,
SHA1_DIGEST_SIZE,
cseed_size, cseed, length, dst);
memxor(dst, o1, length);
return 1;
}
/*-
* tls12_prf:
* @mac_ctx: a MAC context initialized with key being the secret
* @update: a MAC update function
* @digest: a MAC digest function
* @digest_size: the MAC output size
* @label_size: the size of the label
* @label: the label to apply
* @seed_size: the seed size
* @seed: the seed
* @length: size of desired PRF output
* @dst: the location to store output
*
* The TLS 1.2 Pseudo-Random-Function (PRF).
*
* Returns: zero on failure, non zero on success.
-*/
int
tls12_prf(void *mac_ctx,
nettle_hash_update_func *update,
nettle_hash_digest_func *digest,
size_t digest_size,
size_t label_size, const char *label,
size_t seed_size, const uint8_t *seed,
size_t length, uint8_t *dst)
{
size_t cseed_size = seed_size + label_size;
uint8_t cseed[MAX_SEED_SIZE];
if (cseed_size > MAX_SEED_SIZE)
return 0;
memcpy(cseed, label, label_size);
memcpy(&cseed[label_size], seed, seed_size);
P_hash(mac_ctx, update, digest, digest_size,
cseed_size, cseed, length, dst);
return 1;
}
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