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
br_aes_ct64_cbcdec_init(br_aes_ct64_cbcdec_keys * ctx,const void * key,size_t len)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
br_aes_ct64_cbcdec_run(const br_aes_ct64_cbcdec_keys * ctx,void * iv,void * data,size_t len)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