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 */
28 void
29 br_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 */
37 void
38 br_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 */
96 const 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