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_ct64_cbcdec_init(br_aes_ct64_cbcdec_keys *ctx,
30	const void *key, size_t len)
31{
32	ctx->vtable = &br_aes_ct64_cbcdec_vtable;
33	ctx->num_rounds = br_aes_ct64_keysched(ctx->skey, key, len);
34}
35
36/* see bearssl_block.h */
37void
38br_aes_ct64_cbcdec_run(const br_aes_ct64_cbcdec_keys *ctx,
39	void *iv, void *data, size_t len)
40{
41	unsigned char *buf;
42	uint64_t sk_exp[120];
43	uint32_t ivw[4];
44
45	br_aes_ct64_skey_expand(sk_exp, ctx->num_rounds, ctx->skey);
46	br_range_dec32le(ivw, 4, iv);
47	buf = data;
48	while (len > 0) {
49		uint64_t q[8];
50		uint32_t w1[16], w2[16];
51		int i;
52
53		if (len >= 64) {
54			br_range_dec32le(w1, 16, buf);
55		} else {
56			br_range_dec32le(w1, len >> 2, buf);
57		}
58		for (i = 0; i < 4; i ++) {
59			br_aes_ct64_interleave_in(
60				&q[i], &q[i + 4], w1 + (i << 2));
61		}
62		br_aes_ct64_ortho(q);
63		br_aes_ct64_bitslice_decrypt(ctx->num_rounds, sk_exp, q);
64		br_aes_ct64_ortho(q);
65		for (i = 0; i < 4; i ++) {
66			br_aes_ct64_interleave_out(
67				w2 + (i << 2), q[i], q[i + 4]);
68		}
69		for (i = 0; i < 4; i ++) {
70			w2[i] ^= ivw[i];
71		}
72		if (len >= 64) {
73			for (i = 4; i < 16; i ++) {
74				w2[i] ^= w1[i - 4];
75			}
76			memcpy(ivw, w1 + 12, sizeof ivw);
77			br_range_enc32le(buf, w2, 16);
78		} else {
79			int j;
80
81			j = (int)(len >> 2);
82			for (i = 4; i < j; i ++) {
83				w2[i] ^= w1[i - 4];
84			}
85			memcpy(ivw, w1 + j - 4, sizeof ivw);
86			br_range_enc32le(buf, w2, j);
87			break;
88		}
89		buf += 64;
90		len -= 64;
91	}
92	br_range_enc32le(iv, ivw, 4);
93}
94
95/* see bearssl_block.h */
96const br_block_cbcdec_class br_aes_ct64_cbcdec_vtable = {
97	sizeof(br_aes_ct64_cbcdec_keys),
98	16,
99	4,
100	(void (*)(const br_block_cbcdec_class **, const void *, size_t))
101		&br_aes_ct64_cbcdec_init,
102	(void (*)(const br_block_cbcdec_class *const *, void *, void *, size_t))
103		&br_aes_ct64_cbcdec_run
104};
105