xref: /freebsd-src/contrib/bearssl/src/ssl/prf.c (revision 2aaf9152a852aba9eb2036b95f4948ee77988826)
1*0957b409SSimon J. Gerraty /*
2*0957b409SSimon J. Gerraty  * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
3*0957b409SSimon J. Gerraty  *
4*0957b409SSimon J. Gerraty  * Permission is hereby granted, free of charge, to any person obtaining
5*0957b409SSimon J. Gerraty  * a copy of this software and associated documentation files (the
6*0957b409SSimon J. Gerraty  * "Software"), to deal in the Software without restriction, including
7*0957b409SSimon J. Gerraty  * without limitation the rights to use, copy, modify, merge, publish,
8*0957b409SSimon J. Gerraty  * distribute, sublicense, and/or sell copies of the Software, and to
9*0957b409SSimon J. Gerraty  * permit persons to whom the Software is furnished to do so, subject to
10*0957b409SSimon J. Gerraty  * the following conditions:
11*0957b409SSimon J. Gerraty  *
12*0957b409SSimon J. Gerraty  * The above copyright notice and this permission notice shall be
13*0957b409SSimon J. Gerraty  * included in all copies or substantial portions of the Software.
14*0957b409SSimon J. Gerraty  *
15*0957b409SSimon J. Gerraty  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16*0957b409SSimon J. Gerraty  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17*0957b409SSimon J. Gerraty  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18*0957b409SSimon J. Gerraty  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
19*0957b409SSimon J. Gerraty  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
20*0957b409SSimon J. Gerraty  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
21*0957b409SSimon J. Gerraty  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22*0957b409SSimon J. Gerraty  * SOFTWARE.
23*0957b409SSimon J. Gerraty  */
24*0957b409SSimon J. Gerraty 
25*0957b409SSimon J. Gerraty #include "inner.h"
26*0957b409SSimon J. Gerraty 
27*0957b409SSimon J. Gerraty /* see inner.h */
28*0957b409SSimon J. Gerraty void
br_tls_phash(void * dst,size_t len,const br_hash_class * dig,const void * secret,size_t secret_len,const char * label,size_t seed_num,const br_tls_prf_seed_chunk * seed)29*0957b409SSimon J. Gerraty br_tls_phash(void *dst, size_t len,
30*0957b409SSimon J. Gerraty 	const br_hash_class *dig,
31*0957b409SSimon J. Gerraty 	const void *secret, size_t secret_len, const char *label,
32*0957b409SSimon J. Gerraty 	size_t seed_num, const br_tls_prf_seed_chunk *seed)
33*0957b409SSimon J. Gerraty {
34*0957b409SSimon J. Gerraty 	unsigned char *buf;
35*0957b409SSimon J. Gerraty 	unsigned char tmp[64], a[64];
36*0957b409SSimon J. Gerraty 	br_hmac_key_context kc;
37*0957b409SSimon J. Gerraty 	br_hmac_context hc;
38*0957b409SSimon J. Gerraty 	size_t label_len, hlen, u;
39*0957b409SSimon J. Gerraty 
40*0957b409SSimon J. Gerraty 	if (len == 0) {
41*0957b409SSimon J. Gerraty 		return;
42*0957b409SSimon J. Gerraty 	}
43*0957b409SSimon J. Gerraty 	buf = dst;
44*0957b409SSimon J. Gerraty 	for (label_len = 0; label[label_len]; label_len ++);
45*0957b409SSimon J. Gerraty 	hlen = br_digest_size(dig);
46*0957b409SSimon J. Gerraty 	br_hmac_key_init(&kc, dig, secret, secret_len);
47*0957b409SSimon J. Gerraty 	br_hmac_init(&hc, &kc, 0);
48*0957b409SSimon J. Gerraty 	br_hmac_update(&hc, label, label_len);
49*0957b409SSimon J. Gerraty 	for (u = 0; u < seed_num; u ++) {
50*0957b409SSimon J. Gerraty 		br_hmac_update(&hc, seed[u].data, seed[u].len);
51*0957b409SSimon J. Gerraty 	}
52*0957b409SSimon J. Gerraty 	br_hmac_out(&hc, a);
53*0957b409SSimon J. Gerraty 	for (;;) {
54*0957b409SSimon J. Gerraty 		br_hmac_init(&hc, &kc, 0);
55*0957b409SSimon J. Gerraty 		br_hmac_update(&hc, a, hlen);
56*0957b409SSimon J. Gerraty 		br_hmac_update(&hc, label, label_len);
57*0957b409SSimon J. Gerraty 		for (u = 0; u < seed_num; u ++) {
58*0957b409SSimon J. Gerraty 			br_hmac_update(&hc, seed[u].data, seed[u].len);
59*0957b409SSimon J. Gerraty 		}
60*0957b409SSimon J. Gerraty 		br_hmac_out(&hc, tmp);
61*0957b409SSimon J. Gerraty 		for (u = 0; u < hlen && u < len; u ++) {
62*0957b409SSimon J. Gerraty 			buf[u] ^= tmp[u];
63*0957b409SSimon J. Gerraty 		}
64*0957b409SSimon J. Gerraty 		buf += u;
65*0957b409SSimon J. Gerraty 		len -= u;
66*0957b409SSimon J. Gerraty 		if (len == 0) {
67*0957b409SSimon J. Gerraty 			return;
68*0957b409SSimon J. Gerraty 		}
69*0957b409SSimon J. Gerraty 		br_hmac_init(&hc, &kc, 0);
70*0957b409SSimon J. Gerraty 		br_hmac_update(&hc, a, hlen);
71*0957b409SSimon J. Gerraty 		br_hmac_out(&hc, a);
72*0957b409SSimon J. Gerraty 	}
73*0957b409SSimon J. Gerraty }
74