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
27/* see bearssl_block.h */
28void
29br_aes_small_cbcdec_init(br_aes_small_cbcdec_keys *ctx,
30	const void *key, size_t len)
31{
32	ctx->vtable = &br_aes_small_cbcdec_vtable;
33	ctx->num_rounds = br_aes_keysched(ctx->skey, key, len);
34}
35
36/* see bearssl_block.h */
37void
38br_aes_small_cbcdec_run(const br_aes_small_cbcdec_keys *ctx,
39	void *iv, void *data, size_t len)
40{
41	unsigned char *buf, *ivbuf;
42
43	ivbuf = iv;
44	buf = data;
45	while (len > 0) {
46		unsigned char tmp[16];
47		int i;
48
49		memcpy(tmp, buf, 16);
50		br_aes_small_decrypt(ctx->num_rounds, ctx->skey, buf);
51		for (i = 0; i < 16; i ++) {
52			buf[i] ^= ivbuf[i];
53		}
54		memcpy(ivbuf, tmp, 16);
55		buf += 16;
56		len -= 16;
57	}
58}
59
60/* see bearssl_block.h */
61const br_block_cbcdec_class br_aes_small_cbcdec_vtable = {
62	sizeof(br_aes_small_cbcdec_keys),
63	16,
64	4,
65	(void (*)(const br_block_cbcdec_class **, const void *, size_t))
66		&br_aes_small_cbcdec_init,
67	(void (*)(const br_block_cbcdec_class *const *, void *, void *, size_t))
68		&br_aes_small_cbcdec_run
69};
70