Fixed comment.
[BearSSL] / src / symcipher / des_support.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 inner.h */
28 void
29 br_des_do_IP(uint32_t *xl, uint32_t *xr)
30 {
31 /*
32 * Permutation algorithm is initially from Richard Outerbridge;
33 * implementation here is adapted from Crypto++ "des.cpp" file
34 * (which is in public domain).
35 */
36 uint32_t l, r, t;
37
38 l = *xl;
39 r = *xr;
40 t = ((l >> 4) ^ r) & (uint32_t)0x0F0F0F0F;
41 r ^= t;
42 l ^= t << 4;
43 t = ((l >> 16) ^ r) & (uint32_t)0x0000FFFF;
44 r ^= t;
45 l ^= t << 16;
46 t = ((r >> 2) ^ l) & (uint32_t)0x33333333;
47 l ^= t;
48 r ^= t << 2;
49 t = ((r >> 8) ^ l) & (uint32_t)0x00FF00FF;
50 l ^= t;
51 r ^= t << 8;
52 t = ((l >> 1) ^ r) & (uint32_t)0x55555555;
53 r ^= t;
54 l ^= t << 1;
55 *xl = l;
56 *xr = r;
57 }
58
59 /* see inner.h */
60 void
61 br_des_do_invIP(uint32_t *xl, uint32_t *xr)
62 {
63 /*
64 * See br_des_do_IP().
65 */
66 uint32_t l, r, t;
67
68 l = *xl;
69 r = *xr;
70 t = ((l >> 1) ^ r) & 0x55555555;
71 r ^= t;
72 l ^= t << 1;
73 t = ((r >> 8) ^ l) & 0x00FF00FF;
74 l ^= t;
75 r ^= t << 8;
76 t = ((r >> 2) ^ l) & 0x33333333;
77 l ^= t;
78 r ^= t << 2;
79 t = ((l >> 16) ^ r) & 0x0000FFFF;
80 r ^= t;
81 l ^= t << 16;
82 t = ((l >> 4) ^ r) & 0x0F0F0F0F;
83 r ^= t;
84 l ^= t << 4;
85 *xl = l;
86 *xr = r;
87 }
88
89 /* see inner.h */
90 void
91 br_des_keysched_unit(uint32_t *skey, const void *key)
92 {
93 uint32_t xl, xr, kl, kr;
94 int i;
95
96 xl = br_dec32be(key);
97 xr = br_dec32be((const unsigned char *)key + 4);
98
99 /*
100 * Permutation PC-1 is quite similar to the IP permutation.
101 * Definition of IP (in FIPS 46-3 notations) is:
102 * 58 50 42 34 26 18 10 2
103 * 60 52 44 36 28 20 12 4
104 * 62 54 46 38 30 22 14 6
105 * 64 56 48 40 32 24 16 8
106 * 57 49 41 33 25 17 9 1
107 * 59 51 43 35 27 19 11 3
108 * 61 53 45 37 29 21 13 5
109 * 63 55 47 39 31 23 15 7
110 *
111 * Definition of PC-1 is:
112 * 57 49 41 33 25 17 9 1
113 * 58 50 42 34 26 18 10 2
114 * 59 51 43 35 27 19 11 3
115 * 60 52 44 36
116 * 63 55 47 39 31 23 15 7
117 * 62 54 46 38 30 22 14 6
118 * 61 53 45 37 29 21 13 5
119 * 28 20 12 4
120 */
121 br_des_do_IP(&xl, &xr);
122 kl = ((xr & (uint32_t)0xFF000000) >> 4)
123 | ((xl & (uint32_t)0xFF000000) >> 12)
124 | ((xr & (uint32_t)0x00FF0000) >> 12)
125 | ((xl & (uint32_t)0x00FF0000) >> 20);
126 kr = ((xr & (uint32_t)0x000000FF) << 20)
127 | ((xl & (uint32_t)0x0000FF00) << 4)
128 | ((xr & (uint32_t)0x0000FF00) >> 4)
129 | ((xl & (uint32_t)0x000F0000) >> 16);
130
131 /*
132 * For each round, rotate the two 28-bit words kl and kr.
133 * The extraction of the 48-bit subkey (PC-2) is not done yet.
134 */
135 for (i = 0; i < 16; i ++) {
136 if ((1 << i) & 0x8103) {
137 kl = (kl << 1) | (kl >> 27);
138 kr = (kr << 1) | (kr >> 27);
139 } else {
140 kl = (kl << 2) | (kl >> 26);
141 kr = (kr << 2) | (kr >> 26);
142 }
143 kl &= (uint32_t)0x0FFFFFFF;
144 kr &= (uint32_t)0x0FFFFFFF;
145 skey[(i << 1) + 0] = kl;
146 skey[(i << 1) + 1] = kr;
147 }
148 }
149
150 /* see inner.h */
151 void
152 br_des_rev_skey(uint32_t *skey)
153 {
154 int i;
155
156 for (i = 0; i < 16; i += 2) {
157 uint32_t t;
158
159 t = skey[i + 0];
160 skey[i + 0] = skey[30 - i];
161 skey[30 - i] = t;
162 t = skey[i + 1];
163 skey[i + 1] = skey[31 - i];
164 skey[31 - i] = t;
165 }
166 }