3 * $Id: tea.c,v 1.2 2000/07/29 09:56:47 mdw Exp $
5 * The Tiny Encryption Algorithm
7 * (c) 2000 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Catacomb.
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.
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.
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,
30 /*----- Revision history --------------------------------------------------*
33 * Revision 1.2 2000/07/29 09:56:47 mdw
34 * Allow the number of rounds to be configured. This isn't exported
35 * through the gcipher interface, but it may be useful anyway.
37 * Revision 1.1 2000/07/15 13:44:31 mdw
42 /*----- Header files ------------------------------------------------------*/
44 #include <mLib/bits.h>
51 /*----- Global variables --------------------------------------------------*/
53 const octet tea_keysz[] = { KSZ_RANGE, TEA_KEYSZ, 0, 16, 1 };
55 /*----- Main code ---------------------------------------------------------*/
57 /* --- @tea_init@ --- *
59 * Arguments: @tea_ctx *k@ = pointer to key block
60 * @const void *buf@ = pointer to key buffer
61 * @size_t sz@ = size of key material
65 * Use: Initializes a TEA key buffer. The key buffer must be 16
69 void tea_init(tea_ctx *k, const void *buf, size_t sz)
79 memset(kb + sz, 0, sizeof(kb) - sz);
83 k->ka = LOAD32(p + 0); k->kb = LOAD32(p + 4);
84 k->kc = LOAD32(p + 8); k->kd = LOAD32(p + 12);
91 /* --- @tea_eblk@, @tea_dblk@ --- *
93 * Arguments: @const tea_ctx *k@ = pointer to key block
94 * @const uint32 s[2]@ = pointer to source block
95 * @uint32 d[2]@ = pointer to teatination block
99 * Use: Low-level block encryption and decryption.
102 #define DELTA 0x9e3779b9
104 void tea_eblk(const tea_ctx *k, const uint32 *s, uint32 *d)
106 uint32 y = s[0], z = s[1];
107 uint32 ka = k->ka, kb = k->kb, kc = k->kc, kd = k->kd;
111 for (i = 0; i < k->r; i++) {
113 y = U32(y + (((z << 4) + ka) ^ (z + n) ^ ((z >> 5) + kb)));
114 z = U32(z + (((y << 4) + kc) ^ (y + n) ^ ((y >> 5) + kd)));
119 void tea_dblk(const tea_ctx *k, const uint32 *s, uint32 *d)
121 uint32 y = s[0], z = s[1];
122 uint32 ka = k->ka, kb = k->kb, kc = k->kc, kd = k->kd;
123 uint32 n = DELTA * k->r;
126 for (i = 0; i < k->r; i++) {
127 z = U32(z - (((y << 4) + kc) ^ (y + n) ^ ((y >> 5) + kd)));
128 y = U32(y - (((z << 4) + ka) ^ (z + n) ^ ((z >> 5) + kb)));
136 /*----- That's all, folks -------------------------------------------------*/