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[u/mdw/catacomb] / cast256.c
1 /* -*-c-*-
2 *
3 * $Id: cast256.c,v 1.1 2000/06/17 10:49:14 mdw Exp $
4 *
5 * The CAST-256 block cipher
6 *
7 * (c) 2000 Straylight/Edgeware
8 */
9
10 /*----- Licensing notice --------------------------------------------------*
11 *
12 * This file is part of Catacomb.
13 *
14 * Catacomb is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU Library General Public License as
16 * published by the Free Software Foundation; either version 2 of the
17 * License, or (at your option) any later version.
18 *
19 * Catacomb is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU Library General Public License for more details.
23 *
24 * You should have received a copy of the GNU Library General Public
25 * License along with Catacomb; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
27 * MA 02111-1307, USA.
28 */
29
30 /*----- Revision history --------------------------------------------------*
31 *
32 * $Log: cast256.c,v $
33 * Revision 1.1 2000/06/17 10:49:14 mdw
34 * New cipher.
35 *
36 */
37
38 /*----- Header files ------------------------------------------------------*/
39
40 #include <assert.h>
41 #include <stdio.h>
42 #include <stdlib.h>
43 #include <string.h>
44
45 #include <mLib/bits.h>
46
47 #include "blkc.h"
48 #include "cast-base.h"
49 #include "cast256.h"
50 #include "gcipher.h"
51 #include "paranoia.h"
52
53 /*----- Global variables --------------------------------------------------*/
54
55 const octet cast256_keysz[] = { KSZ_RANGE, CAST256_KEYSZ, 0, 32, 1 };
56
57 /*----- Main code ---------------------------------------------------------*/
58
59 /* --- @cast256_init@ --- *
60 *
61 * Arguments: @cast128_ctx *k@ = pointer to key block to fill in
62 * @const void *buf@ = pointer to buffer of key material
63 * @size_t sz@ = size of key material
64 *
65 * Returns: ---
66 *
67 * Use: Initializes a CAST-256 key buffer. CAST-256 accepts
68 * 256-bit keys or shorter.
69 */
70
71 void cast256_init(cast256_ctx *k, const void *buf, size_t sz)
72 {
73 const octet *p = buf;
74 uint32 kk[8];
75 uint32 *km;
76 octet *kr;
77 unsigned i, j;
78 uint32 a, b, c, d, e, f, g, h;
79 uint32 m;
80 unsigned r;
81
82 /* --- Fiddle with the key size --- */
83
84 KSZ_ASSERT(cast256, sz);
85
86 /* --- Read the key into the array --- */
87
88 i = 0;
89 b = 32; a = 0;
90 for (;;) {
91 if (!sz)
92 break;
93 b -= 8;
94 a |= ((uint32)*p++ << b);
95 sz--;
96 if (b == 0) {
97 kk[i++] = a;
98 if (i == 8)
99 break;
100 a = 0;
101 b = 32;
102 }
103 }
104
105 for (; i < 8; i++) {
106 kk[i] = a;
107 a = 0;
108 }
109
110 /* --- Read the key words out --- */
111
112 a = kk[0]; b = kk[1]; c = kk[2]; d = kk[3];
113 e = kk[4]; f = kk[5]; g = kk[6]; h = kk[7];
114
115 #define ROOT2 0x5a827999
116 #define ROOT3 0x6ed9eba1
117
118 m = ROOT2;
119 r = 19;
120
121 km = k->km;
122 kr = k->kr;
123 for (i = 0; i < 12; i++) {
124 for (j = 0; j < 2; j++) {
125 CAST_R1(m, r, g, h); m += ROOT3; r = (r + 17) & 0x1f;
126 CAST_R2(m, r, f, g); m += ROOT3; r = (r + 17) & 0x1f;
127 CAST_R3(m, r, e, f); m += ROOT3; r = (r + 17) & 0x1f;
128 CAST_R1(m, r, d, e); m += ROOT3; r = (r + 17) & 0x1f;
129 CAST_R2(m, r, c, d); m += ROOT3; r = (r + 17) & 0x1f;
130 CAST_R3(m, r, b, c); m += ROOT3; r = (r + 17) & 0x1f;
131 CAST_R1(m, r, a, b); m += ROOT3; r = (r + 17) & 0x1f;
132 CAST_R2(m, r, h, a); m += ROOT3; r = (r + 17) & 0x1f;
133 }
134 km[0] = h; km[1] = f; km[2] = d; km[3] = b;
135 kr[0] = a & 0x1f; kr[1] = c & 0x1f; kr[2] = e & 0x1f; kr[3] = g & 0x1f;
136 km += 4; kr += 4;
137 }
138 }
139
140 /* --- @cast256_eblk@, @cast256_dblk@ --- *
141 *
142 * Arguments: @const cast256_ctx *k@ = pointer to key block
143 * @const uint32 s[2]@ = pointer to source block
144 * @uint32 d[2]@ = pointer to destination block
145 *
146 * Returns: ---
147 *
148 * Use: Low-level block encryption and decryption.
149 */
150
151 #define Q0(k, r, a, b, c, d) do { \
152 CAST_R1(k[0], r[0], c, d); \
153 CAST_R2(k[1], r[1], b, c); \
154 CAST_R3(k[2], r[2], a, b); \
155 CAST_R1(k[3], r[3], d, a); \
156 } while (0)
157
158 #define Q1(k, r, a, b, c, d) do { \
159 CAST_R1(k[3], r[3], d, a); \
160 CAST_R3(k[2], r[2], a, b); \
161 CAST_R2(k[1], r[1], b, c); \
162 CAST_R1(k[0], r[0], c, d); \
163 } while (0)
164
165 void cast256_eblk(const cast256_ctx *k, const uint32 *s, uint32 *d)
166 {
167 uint32 aa = s[0], bb = s[1], cc = s[2], dd = s[3];
168 const uint32 *km = k->km;
169 const octet *kr = k->kr;
170
171 Q0(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
172 Q0(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
173 Q0(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
174 Q0(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
175 Q0(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
176 Q0(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
177
178 Q1(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
179 Q1(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
180 Q1(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
181 Q1(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
182 Q1(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
183 Q1(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
184
185 d[0] = aa; d[1] = bb; d[2] = cc; d[3] = dd;
186 }
187
188 void cast256_dblk(const cast256_ctx *k, const uint32 *s, uint32 *d)
189 {
190 uint32 aa = s[0], bb = s[1], cc = s[2], dd = s[3];
191 const uint32 *km = k->km + 48;
192 const octet *kr = k->kr + 48;
193
194 km -= 4; kr -= 4; Q0(km, kr, aa, bb, cc, dd);
195 km -= 4; kr -= 4; Q0(km, kr, aa, bb, cc, dd);
196 km -= 4; kr -= 4; Q0(km, kr, aa, bb, cc, dd);
197 km -= 4; kr -= 4; Q0(km, kr, aa, bb, cc, dd);
198 km -= 4; kr -= 4; Q0(km, kr, aa, bb, cc, dd);
199 km -= 4; kr -= 4; Q0(km, kr, aa, bb, cc, dd);
200
201 km -= 4; kr -= 4; Q1(km, kr, aa, bb, cc, dd);
202 km -= 4; kr -= 4; Q1(km, kr, aa, bb, cc, dd);
203 km -= 4; kr -= 4; Q1(km, kr, aa, bb, cc, dd);
204 km -= 4; kr -= 4; Q1(km, kr, aa, bb, cc, dd);
205 km -= 4; kr -= 4; Q1(km, kr, aa, bb, cc, dd);
206 km -= 4; kr -= 4; Q1(km, kr, aa, bb, cc, dd);
207
208 d[0] = aa; d[1] = bb; d[2] = cc; d[3] = dd;
209 }
210
211 BLKC_TEST(CAST256, cast256)
212
213 /*----- That's all, folks -------------------------------------------------*/
Catacomb cryptographic library (downstream of http://git.distorted.org.uk/~mdw/catacomb/)