3 * $Id: xtea.c,v 1.2 2000/07/29 09:56:47 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 /*----- 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 xtea_keysz
[] = { KSZ_RANGE
, XTEA_KEYSZ
, 0, 16, 1 };
55 /*----- Main code ---------------------------------------------------------*/
57 /* --- @xtea_init@ --- *
59 * Arguments: @xtea_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 an XTEA key buffer. The key buffer must be 16
69 void xtea_init(xtea_ctx
*k
, const void *buf
, size_t sz
)
79 memset(kb
+ sz
, 0, sizeof(kb
) - sz
);
83 k
->k
[0] = LOAD32(p
+ 0); k
->k
[1] = LOAD32(p
+ 4);
84 k
->k
[2] = LOAD32(p
+ 8); k
->k
[3] = LOAD32(p
+ 12);
91 /* --- @xtea_eblk@, @xtea_dblk@ --- *
93 * Arguments: @const xtea_ctx *k@ = pointer to key block
94 * @const uint32 s[2]@ = pointer to source block
95 * @uint32 d[2]@ = pointer to xteatination block
99 * Use: Low-level block encryption and decryption.
102 #define DELTA 0x9e3779b9
104 void xtea_eblk(const xtea_ctx
*k
, const uint32
*s
, uint32
*d
)
106 uint32 y
= s
[0], z
= s
[1];
110 for (i
= 0; i
< k
->r
; i
++) {
111 y
= U32(y
+ ((((z
<< 4) ^ (z
>> 5)) + z
) ^ (n
+ k
->k
[n
& 3])));
113 z
= U32(z
+ ((((y
<< 4) ^ (y
>> 5)) + y
) ^ (n
+ k
->k
[(n
>> 11) & 3])));
118 void xtea_dblk(const xtea_ctx
*k
, const uint32
*s
, uint32
*d
)
120 uint32 y
= s
[0], z
= s
[1];
121 uint32 n
= DELTA
* k
->r
;
124 for (i
= 0; i
< k
->r
; i
++) {
125 z
= U32(z
- ((((y
<< 4) ^ (y
>> 5)) + y
) ^ (n
+ k
->k
[(n
>> 11) & 3])));
127 y
= U32(y
- ((((z
<< 4) ^ (z
>> 5)) + z
) ^ (n
+ k
->k
[n
& 3])));
132 BLKC_TEST(XTEA
, xtea
)
134 /*----- That's all, folks -------------------------------------------------*/