3 * $Id: xtea.c,v 1.3 2004/04/08 01:36:15 mdw Exp $
5 * The Extended 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 /*----- Header files ------------------------------------------------------*/
32 #include <mLib/bits.h>
39 /*----- Global variables --------------------------------------------------*/
41 const octet xtea_keysz
[] = { KSZ_RANGE
, XTEA_KEYSZ
, 0, 16, 1 };
43 /*----- Main code ---------------------------------------------------------*/
45 /* --- @xtea_init@ --- *
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
53 * Use: Initializes an XTEA key buffer. The key buffer must be 16
57 void xtea_init(xtea_ctx
*k
, const void *buf
, size_t sz
)
67 memset(kb
+ sz
, 0, sizeof(kb
) - sz
);
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);
79 /* --- @xtea_eblk@, @xtea_dblk@ --- *
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
87 * Use: Low-level block encryption and decryption.
90 #define DELTA 0x9e3779b9
92 void xtea_eblk(const xtea_ctx
*k
, const uint32
*s
, uint32
*d
)
94 uint32 y
= s
[0], z
= s
[1];
98 for (i
= 0; i
< k
->r
; i
++) {
99 y
= U32(y
+ ((((z
<< 4) ^ (z
>> 5)) + z
) ^ (n
+ k
->k
[n
& 3])));
101 z
= U32(z
+ ((((y
<< 4) ^ (y
>> 5)) + y
) ^ (n
+ k
->k
[(n
>> 11) & 3])));
106 void xtea_dblk(const xtea_ctx
*k
, const uint32
*s
, uint32
*d
)
108 uint32 y
= s
[0], z
= s
[1];
109 uint32 n
= DELTA
* k
->r
;
112 for (i
= 0; i
< k
->r
; i
++) {
113 z
= U32(z
- ((((y
<< 4) ^ (y
>> 5)) + y
) ^ (n
+ k
->k
[(n
>> 11) & 3])));
115 y
= U32(y
- ((((z
<< 4) ^ (z
>> 5)) + z
) ^ (n
+ k
->k
[n
& 3])));
120 BLKC_TEST(XTEA
, xtea
)
122 /*----- That's all, folks -------------------------------------------------*/