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