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

   1 /* -*-c-*-
   2  *
   3  * $Id: tea.c,v 1.1 2000/07/15 13:44:31 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 1.1  2000/07/15 13:44:31  mdw
  34  * New ciphers.
  35  *
  36  */
  37
  38 /*----- Header files ------------------------------------------------------*/
  39
  40 #include <mLib/bits.h>
  41
  42 #include "blkc.h"
  43 #include "gcipher.h"
  44 #include "paranoia.h"
  45 #include "tea.h"
  46
  47 /*----- Global variables --------------------------------------------------*/
  48
  49 const octet tea_keysz[] = { KSZ_RANGE, TEA_KEYSZ, 0, 16, 1 };
  50
  51 /*----- Main code ---------------------------------------------------------*/
  52
  53 /* --- @tea_init@ --- *
  54  *
  55  * Arguments:   @tea_ctx *k@ = pointer to key block
  56  *              @const void *buf@ = pointer to key buffer
  57  *              @size_t sz@ = size of key material
  58  *
  59  * Returns:     ---
  60  *
  61  * Use:         Initializes a TEA key buffer.  The key buffer must be 16
  62  *              bytes long.
  63  */
  64
  65 void tea_init(tea_ctx *k, const void *buf, size_t sz)
  66 {
  67   octet kb[16];
  68   const octet *p;
  69
  70   KSZ_ASSERT(tea, sz);
  71   if (sz >= sizeof(kb))
  72     p = buf;
  73   else {
  74     memcpy(kb, buf, sz);
  75     memset(kb + sz, 0, sizeof(kb) - sz);
  76     p = kb;
  77   }
  78
  79   k->ka = LOAD32(p +  0);   k->kb = LOAD32(p +  4);
  80   k->kc = LOAD32(p +  8);   k->kd = LOAD32(p + 12);
  81
  82   if (p == kb)
  83     BURN(kb);
  84 }
  85
  86 /* --- @tea_eblk@, @tea_dblk@ --- *
  87  *
  88  * Arguments:   @const tea_ctx *k@ = pointer to key block
  89  *              @const uint32 s[2]@ = pointer to source block
  90  *              @uint32 d[2]@ = pointer to teatination block
  91  *
  92  * Returns:     ---
  93  *
  94  * Use:         Low-level block encryption and decryption.
  95  */
  96
  97 #define DELTA 0x9e3779b9
  98
  99 void tea_eblk(const tea_ctx *k, const uint32 *s, uint32 *d)
 100 {
 101   uint32 y = s[0], z = s[1];
 102   uint32 ka = k->ka, kb = k->kb, kc = k->kc, kd = k->kd;
 103   uint32 n = 0;
 104   unsigned i;
 105
 106   for (i = 0; i < 32; i++) {
 107     n += DELTA;
 108     y = U32(y + (((z << 4) + ka) ^ (z + n) ^ ((z >> 5) + kb)));
 109     z = U32(z + (((y << 4) + kc) ^ (y + n) ^ ((y >> 5) + kd)));
 110   }
 111   d[0] = y; d[1] = z;
 112 }
 113
 114 void tea_dblk(const tea_ctx *k, const uint32 *s, uint32 *d)
 115 {
 116   uint32 y = s[0], z = s[1];
 117   uint32 ka = k->ka, kb = k->kb, kc = k->kc, kd = k->kd;
 118   uint32 n = DELTA << 5;
 119   unsigned i;
 120
 121   for (i = 0; i < 32; i++) {
 122     z = U32(z - (((y << 4) + kc) ^ (y + n) ^ ((y >> 5) + kd)));
 123     y = U32(y - (((z << 4) + ka) ^ (z + n) ^ ((z >> 5) + kb)));
 124     n -= DELTA;
 125   }
 126   d[0] = y; d[1] = z;
 127 }
 128
 129 BLKC_TEST(TEA, tea)
 130
 131 /*----- That's all, folks -------------------------------------------------*/