git.distorted.org.uk Git - u/mdw/catacomb/blob - tea.c

   1 /* -*-c-*-
   2  *
   3  * $Id: tea.c,v 1.2 2000/07/29 09:56:47 mdw Exp $
   4  *
   5  * The Tiny Encryption Algorithm
   6  *
   7  * (c) 2000 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  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.
  18  *
  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.
  23  *
  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
  30 /*----- Revision history --------------------------------------------------*
  31  *
  32  * $Log: tea.c,v $
  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.
  36  *
  37  * Revision 1.1  2000/07/15 13:44:31  mdw
  38  * New ciphers.
  39  *
  40  */
  41
  42 /*----- Header files ------------------------------------------------------*/
  43
  44 #include <mLib/bits.h>
  45
  46 #include "blkc.h"
  47 #include "gcipher.h"
  48 #include "paranoia.h"
  49 #include "tea.h"
  50
  51 /*----- Global variables --------------------------------------------------*/
  52
  53 const octet tea_keysz[] = { KSZ_RANGE, TEA_KEYSZ, 0, 16, 1 };
  54
  55 /*----- Main code ---------------------------------------------------------*/
  56
  57 /* --- @tea_init@ --- *
  58  *
  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
  62  *
  63  * Returns:     ---
  64  *
  65  * Use:         Initializes a TEA key buffer.  The key buffer must be 16
  66  *              bytes long.
  67  */
  68
  69 void tea_init(tea_ctx *k, const void *buf, size_t sz)
  70 {
  71   octet kb[16];
  72   const octet *p;
  73
  74   KSZ_ASSERT(tea, sz);
  75   if (sz >= sizeof(kb))
  76     p = buf;
  77   else {
  78     memcpy(kb, buf, sz);
  79     memset(kb + sz, 0, sizeof(kb) - sz);
  80     p = kb;
  81   }
  82
  83   k->ka = LOAD32(p +  0); k->kb = LOAD32(p +  4);
  84   k->kc = LOAD32(p +  8); k->kd = LOAD32(p + 12);
  85   k->r = 32;
  86
  87   if (p == kb)
  88     BURN(kb);
  89 }
  90
  91 /* --- @tea_eblk@, @tea_dblk@ --- *
  92  *
  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
  96  *
  97  * Returns:     ---
  98  *
  99  * Use:         Low-level block encryption and decryption.
 100  */
 101
 102 #define DELTA 0x9e3779b9
 103
 104 void tea_eblk(const tea_ctx *k, const uint32 *s, uint32 *d)
 105 {
 106   uint32 y = s[0], z = s[1];
 107   uint32 ka = k->ka, kb = k->kb, kc = k->kc, kd = k->kd;
 108   uint32 n = 0;
 109   unsigned i;
 110
 111   for (i = 0; i < k->r; i++) {
 112     n += DELTA;
 113     y = U32(y + (((z << 4) + ka) ^ (z + n) ^ ((z >> 5) + kb)));
 114     z = U32(z + (((y << 4) + kc) ^ (y + n) ^ ((y >> 5) + kd)));
 115   }
 116   d[0] = y; d[1] = z;
 117 }
 118
 119 void tea_dblk(const tea_ctx *k, const uint32 *s, uint32 *d)
 120 {
 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;
 124   unsigned i;
 125
 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)));
 129     n -= DELTA;
 130   }
 131   d[0] = y; d[1] = z;
 132 }
 133
 134 BLKC_TEST(TEA, tea)
 135
 136 /*----- That's all, folks -------------------------------------------------*/