1/*
2 * Copyright (c) 2016 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
27static inline size_t
28block_size(const br_hash_class *dig)
29{
30	unsigned ls;
31
32	ls = (unsigned)(dig->desc >> BR_HASHDESC_LBLEN_OFF)
33		& BR_HASHDESC_LBLEN_MASK;
34	return (size_t)1 << ls;
35}
36
37static void
38process_key(const br_hash_class **hc, void *ks,
39	const void *key, size_t key_len, unsigned bb)
40{
41	unsigned char tmp[256];
42	size_t blen, u;
43
44	blen = block_size(*hc);
45	memcpy(tmp, key, key_len);
46	for (u = 0; u < key_len; u ++) {
47		tmp[u] ^= (unsigned char)bb;
48	}
49	memset(tmp + key_len, bb, blen - key_len);
50	(*hc)->init(hc);
51	(*hc)->update(hc, tmp, blen);
52	(*hc)->state(hc, ks);
53}
54
55/* see bearssl.h */
56void
57br_hmac_key_init(br_hmac_key_context *kc,
58	const br_hash_class *dig, const void *key, size_t key_len)
59{
60	br_hash_compat_context hc;
61	unsigned char kbuf[64];
62
63	kc->dig_vtable = dig;
64	hc.vtable = dig;
65	if (key_len > block_size(dig)) {
66		dig->init(&hc.vtable);
67		dig->update(&hc.vtable, key, key_len);
68		dig->out(&hc.vtable, kbuf);
69		key = kbuf;
70		key_len = br_digest_size(dig);
71	}
72	process_key(&hc.vtable, kc->ksi, key, key_len, 0x36);
73	process_key(&hc.vtable, kc->kso, key, key_len, 0x5C);
74}
75
76/* see bearssl.h */
77void
78br_hmac_init(br_hmac_context *ctx,
79	const br_hmac_key_context *kc, size_t out_len)
80{
81	const br_hash_class *dig;
82	size_t blen, hlen;
83
84	dig = kc->dig_vtable;
85	blen = block_size(dig);
86	dig->init(&ctx->dig.vtable);
87	dig->set_state(&ctx->dig.vtable, kc->ksi, (uint64_t)blen);
88	memcpy(ctx->kso, kc->kso, sizeof kc->kso);
89	hlen = br_digest_size(dig);
90	if (out_len > 0 && out_len < hlen) {
91		hlen = out_len;
92	}
93	ctx->out_len = hlen;
94}
95
96/* see bearssl.h */
97void
98br_hmac_update(br_hmac_context *ctx, const void *data, size_t len)
99{
100	ctx->dig.vtable->update(&ctx->dig.vtable, data, len);
101}
102
103/* see bearssl.h */
104size_t
105br_hmac_out(const br_hmac_context *ctx, void *out)
106{
107	const br_hash_class *dig;
108	br_hash_compat_context hc;
109	unsigned char tmp[64];
110	size_t blen, hlen;
111
112	dig = ctx->dig.vtable;
113	dig->out(&ctx->dig.vtable, tmp);
114	blen = block_size(dig);
115	dig->init(&hc.vtable);
116	dig->set_state(&hc.vtable, ctx->kso, (uint64_t)blen);
117	hlen = br_digest_size(dig);
118	dig->update(&hc.vtable, tmp, hlen);
119	dig->out(&hc.vtable, tmp);
120	memcpy(out, tmp, ctx->out_len);
121	return ctx->out_len;
122}
123