1/*
2 * Copyright (c) 2018 Thomas Pornin <pornin@bolet.org>
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining
5 * a copy of this software and associated documentation files (the
6 * "Software"), to deal in the Software without restriction, including
7 * without limitation the rights to use, copy, modify, merge, publish,
8 * distribute, sublicense, and/or sell copies of the Software, and to
9 * permit persons to whom the Software is furnished to do so, subject to
10 * the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be
13 * included in all copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
19 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
20 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22 * SOFTWARE.
23 */
24
25#include "inner.h"
26
27/* see inner.h */
28void
29br_mgf1_xor(void *data, size_t len,
30	const br_hash_class *dig, const void *seed, size_t seed_len)
31{
32	unsigned char *buf;
33	size_t u, hlen;
34	uint32_t c;
35
36	buf = data;
37	hlen = br_digest_size(dig);
38	for (u = 0, c = 0; u < len; u += hlen, c ++) {
39		br_hash_compat_context hc;
40		unsigned char tmp[64];
41		size_t v;
42
43		hc.vtable = dig;
44		dig->init(&hc.vtable);
45		dig->update(&hc.vtable, seed, seed_len);
46		br_enc32be(tmp, c);
47		dig->update(&hc.vtable, tmp, 4);
48		dig->out(&hc.vtable, tmp);
49		for (v = 0; v < hlen; v ++) {
50			if ((u + v) >= len) {
51				break;
52			}
53			buf[u + v] ^= tmp[v];
54		}
55	}
56}
57