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ea937a0e | 1 | /* -*-c-*- |
2 | * | |
b817bfc6 | 3 | * $Id: xtea.c,v 1.3 2004/04/08 01:36:15 mdw Exp $ |
ea937a0e | 4 | * |
5 | * The Extended Tiny Encryption Algorithm | |
6 | * | |
7 | * (c) 2000 Straylight/Edgeware | |
8 | */ | |
9 | ||
45c0fd36 | 10 | /*----- Licensing notice --------------------------------------------------* |
ea937a0e | 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. | |
45c0fd36 | 18 | * |
ea937a0e | 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. | |
45c0fd36 | 23 | * |
ea937a0e | 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 | ||
ea937a0e | 30 | /*----- Header files ------------------------------------------------------*/ |
31 | ||
32 | #include <mLib/bits.h> | |
33 | ||
34 | #include "blkc.h" | |
35 | #include "gcipher.h" | |
36 | #include "paranoia.h" | |
37 | #include "xtea.h" | |
38 | ||
39 | /*----- Global variables --------------------------------------------------*/ | |
40 | ||
41 | const octet xtea_keysz[] = { KSZ_RANGE, XTEA_KEYSZ, 0, 16, 1 }; | |
42 | ||
43 | /*----- Main code ---------------------------------------------------------*/ | |
44 | ||
45 | /* --- @xtea_init@ --- * | |
46 | * | |
45c0fd36 MW |
47 | * Arguments: @xtea_ctx *k@ = pointer to key block |
48 | * @const void *buf@ = pointer to key buffer | |
49 | * @size_t sz@ = size of key material | |
ea937a0e | 50 | * |
45c0fd36 | 51 | * Returns: --- |
ea937a0e | 52 | * |
45c0fd36 | 53 | * Use: Initializes an XTEA key buffer. The key buffer must be 16 |
ea937a0e | 54 | * bytes long. |
55 | */ | |
56 | ||
57 | void xtea_init(xtea_ctx *k, const void *buf, size_t sz) | |
58 | { | |
59 | octet kb[16]; | |
60 | const octet *p; | |
61 | ||
62 | KSZ_ASSERT(xtea, sz); | |
63 | if (sz >= sizeof(kb)) | |
64 | p = buf; | |
65 | else { | |
66 | memcpy(kb, buf, sz); | |
67 | memset(kb + sz, 0, sizeof(kb) - sz); | |
68 | p = kb; | |
69 | } | |
70 | ||
45c0fd36 MW |
71 | k->k[0] = LOAD32(p + 0); k->k[1] = LOAD32(p + 4); |
72 | k->k[2] = LOAD32(p + 8); k->k[3] = LOAD32(p + 12); | |
d36cd240 | 73 | k->r = 32; |
ea937a0e | 74 | |
75 | if (p == kb) | |
76 | BURN(kb); | |
77 | } | |
78 | ||
79 | /* --- @xtea_eblk@, @xtea_dblk@ --- * | |
80 | * | |
45c0fd36 MW |
81 | * Arguments: @const xtea_ctx *k@ = pointer to key block |
82 | * @const uint32 s[2]@ = pointer to source block | |
83 | * @uint32 d[2]@ = pointer to xteatination block | |
ea937a0e | 84 | * |
45c0fd36 | 85 | * Returns: --- |
ea937a0e | 86 | * |
45c0fd36 | 87 | * Use: Low-level block encryption and decryption. |
ea937a0e | 88 | */ |
89 | ||
90 | #define DELTA 0x9e3779b9 | |
91 | ||
92 | void xtea_eblk(const xtea_ctx *k, const uint32 *s, uint32 *d) | |
93 | { | |
94 | uint32 y = s[0], z = s[1]; | |
95 | uint32 n = 0; | |
96 | unsigned i; | |
97 | ||
d36cd240 | 98 | for (i = 0; i < k->r; i++) { |
ea937a0e | 99 | y = U32(y + ((((z << 4) ^ (z >> 5)) + z) ^ (n + k->k[n & 3]))); |
100 | n += DELTA; | |
101 | z = U32(z + ((((y << 4) ^ (y >> 5)) + y) ^ (n + k->k[(n >> 11) & 3]))); | |
102 | } | |
103 | d[0] = y; d[1] = z; | |
104 | } | |
105 | ||
106 | void xtea_dblk(const xtea_ctx *k, const uint32 *s, uint32 *d) | |
107 | { | |
108 | uint32 y = s[0], z = s[1]; | |
d36cd240 | 109 | uint32 n = DELTA * k->r; |
ea937a0e | 110 | unsigned i; |
111 | ||
d36cd240 | 112 | for (i = 0; i < k->r; i++) { |
ea937a0e | 113 | z = U32(z - ((((y << 4) ^ (y >> 5)) + y) ^ (n + k->k[(n >> 11) & 3]))); |
114 | n -= DELTA; | |
115 | y = U32(y - ((((z << 4) ^ (z >> 5)) + z) ^ (n + k->k[n & 3]))); | |
116 | } | |
117 | d[0] = y; d[1] = z; | |
118 | } | |
119 | ||
120 | BLKC_TEST(XTEA, xtea) | |
121 | ||
122 | /*----- That's all, folks -------------------------------------------------*/ |