Commit | Line | Data |
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ea937a0e | 1 | /* -*-c-*- |
2 | * | |
ea937a0e | 3 | * The Extended Tiny Encryption Algorithm |
4 | * | |
5 | * (c) 2000 Straylight/Edgeware | |
6 | */ | |
7 | ||
45c0fd36 | 8 | /*----- Licensing notice --------------------------------------------------* |
ea937a0e | 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. | |
45c0fd36 | 16 | * |
ea937a0e | 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. | |
45c0fd36 | 21 | * |
ea937a0e | 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 | ||
ea937a0e | 28 | /*----- Header files ------------------------------------------------------*/ |
29 | ||
30 | #include <mLib/bits.h> | |
31 | ||
32 | #include "blkc.h" | |
33 | #include "gcipher.h" | |
34 | #include "paranoia.h" | |
35 | #include "xtea.h" | |
36 | ||
37 | /*----- Global variables --------------------------------------------------*/ | |
38 | ||
39 | const octet xtea_keysz[] = { KSZ_RANGE, XTEA_KEYSZ, 0, 16, 1 }; | |
40 | ||
41 | /*----- Main code ---------------------------------------------------------*/ | |
42 | ||
43 | /* --- @xtea_init@ --- * | |
44 | * | |
45c0fd36 MW |
45 | * Arguments: @xtea_ctx *k@ = pointer to key block |
46 | * @const void *buf@ = pointer to key buffer | |
47 | * @size_t sz@ = size of key material | |
ea937a0e | 48 | * |
45c0fd36 | 49 | * Returns: --- |
ea937a0e | 50 | * |
45c0fd36 | 51 | * Use: Initializes an XTEA key buffer. The key buffer must be 16 |
ea937a0e | 52 | * bytes long. |
53 | */ | |
54 | ||
55 | void xtea_init(xtea_ctx *k, const void *buf, size_t sz) | |
56 | { | |
57 | octet kb[16]; | |
58 | const octet *p; | |
59 | ||
60 | KSZ_ASSERT(xtea, sz); | |
61 | if (sz >= sizeof(kb)) | |
62 | p = buf; | |
63 | else { | |
64 | memcpy(kb, buf, sz); | |
65 | memset(kb + sz, 0, sizeof(kb) - sz); | |
66 | p = kb; | |
67 | } | |
68 | ||
45c0fd36 MW |
69 | k->k[0] = LOAD32(p + 0); k->k[1] = LOAD32(p + 4); |
70 | k->k[2] = LOAD32(p + 8); k->k[3] = LOAD32(p + 12); | |
d36cd240 | 71 | k->r = 32; |
ea937a0e | 72 | |
73 | if (p == kb) | |
74 | BURN(kb); | |
75 | } | |
76 | ||
77 | /* --- @xtea_eblk@, @xtea_dblk@ --- * | |
78 | * | |
45c0fd36 MW |
79 | * Arguments: @const xtea_ctx *k@ = pointer to key block |
80 | * @const uint32 s[2]@ = pointer to source block | |
81 | * @uint32 d[2]@ = pointer to xteatination block | |
ea937a0e | 82 | * |
45c0fd36 | 83 | * Returns: --- |
ea937a0e | 84 | * |
45c0fd36 | 85 | * Use: Low-level block encryption and decryption. |
ea937a0e | 86 | */ |
87 | ||
88 | #define DELTA 0x9e3779b9 | |
89 | ||
90 | void xtea_eblk(const xtea_ctx *k, const uint32 *s, uint32 *d) | |
91 | { | |
92 | uint32 y = s[0], z = s[1]; | |
93 | uint32 n = 0; | |
94 | unsigned i; | |
95 | ||
d36cd240 | 96 | for (i = 0; i < k->r; i++) { |
ea937a0e | 97 | y = U32(y + ((((z << 4) ^ (z >> 5)) + z) ^ (n + k->k[n & 3]))); |
98 | n += DELTA; | |
99 | z = U32(z + ((((y << 4) ^ (y >> 5)) + y) ^ (n + k->k[(n >> 11) & 3]))); | |
100 | } | |
101 | d[0] = y; d[1] = z; | |
102 | } | |
103 | ||
104 | void xtea_dblk(const xtea_ctx *k, const uint32 *s, uint32 *d) | |
105 | { | |
106 | uint32 y = s[0], z = s[1]; | |
d36cd240 | 107 | uint32 n = DELTA * k->r; |
ea937a0e | 108 | unsigned i; |
109 | ||
d36cd240 | 110 | for (i = 0; i < k->r; i++) { |
ea937a0e | 111 | z = U32(z - ((((y << 4) ^ (y >> 5)) + y) ^ (n + k->k[(n >> 11) & 3]))); |
112 | n -= DELTA; | |
113 | y = U32(y - ((((z << 4) ^ (z >> 5)) + z) ^ (n + k->k[n & 3]))); | |
114 | } | |
115 | d[0] = y; d[1] = z; | |
116 | } | |
117 | ||
118 | BLKC_TEST(XTEA, xtea) | |
119 | ||
120 | /*----- That's all, folks -------------------------------------------------*/ |