Fixed comment.
[BearSSL] / src / symcipher / des_tab_cbcdec.c
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_des_tab_cbcdec_init(br_des_tab_cbcdec_keys *ctx,
30 const void *key, size_t len)
31 {
32 ctx->vtable = &br_des_tab_cbcdec_vtable;
33 ctx->num_rounds = br_des_tab_keysched(ctx->skey, key, len);
34 if (len == 8) {
35 br_des_rev_skey(ctx->skey);
36 } else {
37 int i;
38
39 for (i = 0; i < 48; i += 2) {
40 uint32_t t;
41
42 t = ctx->skey[i];
43 ctx->skey[i] = ctx->skey[94 - i];
44 ctx->skey[94 - i] = t;
45 t = ctx->skey[i + 1];
46 ctx->skey[i + 1] = ctx->skey[95 - i];
47 ctx->skey[95 - i] = t;
48 }
49 }
50 }
51
52 /* see bearssl_block.h */
53 void
54 br_des_tab_cbcdec_run(const br_des_tab_cbcdec_keys *ctx,
55 void *iv, void *data, size_t len)
56 {
57 unsigned char *buf, *ivbuf;
58
59 ivbuf = iv;
60 buf = data;
61 while (len > 0) {
62 unsigned char tmp[8];
63 int i;
64
65 memcpy(tmp, buf, 8);
66 br_des_tab_process_block(ctx->num_rounds, ctx->skey, buf);
67 for (i = 0; i < 8; i ++) {
68 buf[i] ^= ivbuf[i];
69 }
70 memcpy(ivbuf, tmp, 8);
71 buf += 8;
72 len -= 8;
73 }
74 }
75
76 /* see bearssl_block.h */
77 const br_block_cbcdec_class br_des_tab_cbcdec_vtable = {
78 sizeof(br_des_tab_cbcdec_keys),
79 8,
80 3,
81 (void (*)(const br_block_cbcdec_class **, const void *, size_t))
82 &br_des_tab_cbcdec_init,
83 (void (*)(const br_block_cbcdec_class *const *, void *, void *, size_t))
84 &br_des_tab_cbcdec_run
85 };