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1 | /* -*-c-*- |
2 | * |
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3 | * $Id$ |
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4 | * |
5 | * Implementation of DESX |
6 | * |
7 | * (c) 2001 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 | |
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30 | /*----- Header files ------------------------------------------------------*/ |
31 | |
32 | #include <assert.h> |
33 | #include <stdio.h> |
34 | #include <stdlib.h> |
35 | #include <string.h> |
36 | |
37 | #include <mLib/bits.h> |
38 | |
39 | #include "blkc.h" |
40 | #include "des-base.h" |
41 | #include "des.h" |
42 | #include "desx.h" |
43 | #include "desx-tab.h" |
44 | #include "gcipher.h" |
45 | |
46 | /*----- Tables ------------------------------------------------------------*/ |
47 | |
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48 | static const octet s[256] = DESX_S; |
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49 | |
50 | /*----- Global variables --------------------------------------------------*/ |
51 | |
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52 | const octet desx_keysz[] = { KSZ_SET, 23, 7, 8, 15, 16, 24, 0 }; |
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53 | |
54 | /*----- Main code ---------------------------------------------------------*/ |
55 | |
56 | /* --- @desx_init@ --- * |
57 | * |
58 | * Arguments: @desx_ctx *k@ = pointer to key block |
59 | * @const void *buf@ = pointer to key buffer |
60 | * @size_t sz@ = size of key material |
61 | * |
62 | * Returns: --- |
63 | * |
64 | * Use: Initializes a DESX key buffer. The key buffer contains, in |
65 | * order, a single-DES key (either 7 or 8 bytes), an optional |
66 | * 8-byte pre-whitening key, and an optional 8-byte |
67 | * port-whitening key. If no whitening keys are specified, the |
68 | * algorithm becomes the same as single-DES. |
69 | */ |
70 | |
71 | static void mangle(octet *b, const octet *p) |
72 | { |
73 | unsigned i; |
74 | |
75 | for (i = 0; i < 8; i++) |
76 | b[i] = *p++ ^ s[b[i] ^ b[(i + 1) & 7u]]; |
77 | } |
78 | |
79 | void desx_init(desx_ctx *k, const void *buf, size_t sz) |
80 | { |
81 | const octet *p = buf, *kk = buf; |
82 | size_t n; |
83 | |
84 | KSZ_ASSERT(desx, sz); |
85 | |
86 | n = sz % 8 == 7 ? 7 : 8; |
87 | des_init(&k->k, p, n); |
88 | p += n; |
89 | sz -= n; |
90 | if (!sz) |
91 | k->prea = k->preb = k->posta = k->postb = 0; |
92 | else { |
93 | const octet *q = p; |
94 | k->prea = LOAD32(q + 0); |
95 | k->preb = LOAD32(q + 4); |
96 | p += 8; |
97 | sz -= 8; |
98 | if (sz) { |
99 | k->posta = LOAD32(p + 0); |
100 | k->postb = LOAD32(p + 4); |
101 | } else { |
102 | octet b[16]; |
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103 | uint32 x, y; |
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104 | |
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105 | des_expand(kk, n, &x, &y); |
106 | STORE32(b + 8, x); STORE32(b + 12, y); |
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107 | memset(b, 0, 8); |
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108 | mangle(b, b + 8); |
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109 | mangle(b, q); |
110 | k->posta = LOAD32(b + 0); |
111 | k->postb = LOAD32(b + 4); |
112 | } |
113 | } |
114 | } |
115 | |
116 | /* --- @desx_eblk@, @desx_dblk@ --- * |
117 | * |
118 | * Arguments: @const desx_ctx *k@ = pointer to key block |
119 | * @const uint32 s[2]@ = pointer to source block |
120 | * @uint32 d[2]@ = pointer to destination block |
121 | * |
122 | * Returns: --- |
123 | * |
124 | * Use: Low-level block encryption and decryption. |
125 | */ |
126 | |
127 | void desx_eblk(const desx_ctx *k, const uint32 *s, uint32 *d) |
128 | { |
129 | uint32 x = s[0], y = s[1]; |
130 | x ^= k->prea; y ^= k->preb; |
131 | DES_IP(x, y); |
132 | DES_EBLK(k->k.k, x, y, x, y); |
133 | DES_IPINV(x, y); |
134 | x ^= k->posta; y ^= k->postb; |
135 | d[0] = x, d[1] = y; |
136 | } |
137 | |
138 | void desx_dblk(const desx_ctx *k, const uint32 *s, uint32 *d) |
139 | { |
140 | uint32 x = s[0], y = s[1]; |
141 | x ^= k->posta; y ^= k->postb; |
142 | DES_IP(x, y); |
143 | DES_DBLK(k->k.k, x, y, x, y); |
144 | DES_IPINV(x, y); |
145 | x ^= k->prea; y ^= k->preb; |
146 | d[0] = x, d[1] = y; |
147 | } |
148 | |
149 | BLKC_TEST(DESX, desx) |
150 | |
151 | /*----- That's all, folks -------------------------------------------------*/ |