chiark - git - mdw - catacomb/blob - rc5.c

   1 /* -*-c-*-
   2  *
   3  * $Id: rc5.c,v 1.2 2000/06/17 11:56:00 mdw Exp $
   4  *
   5  * The RC5-32/12 block cipher
   6  *
   7  * (c) 1999 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: rc5.c,v $
  33  * Revision 1.2  2000/06/17 11:56:00  mdw
  34  * New key size interface.  Use secure arena for memory allocation.
  35  *
  36  * Revision 1.1  1999/09/03 08:41:12  mdw
  37  * Initial import.
  38  *
  39  */
  40
  41 /*----- Header files ------------------------------------------------------*/
  42
  43 #include <assert.h>
  44 #include <stdlib.h>
  45 #include <string.h>
  46
  47 #include <mLib/alloc.h>
  48 #include <mLib/bits.h>
  49
  50 #include "arena.h"
  51 #include "blkc.h"
  52 #include "gcipher.h"
  53 #include "rc5.h"
  54
  55 /*----- Global variables --------------------------------------------------*/
  56
  57 const octet rc5_keysz[] = { KSZ_RANGE, RC5_KEYSZ, 1, 255, 1 };
  58
  59 /*----- Internal magical constants ----------------------------------------*/
  60
  61 #define T ((RC5_ROUNDS + 1) * 2)
  62 #define P 0xb7e15163
  63 #define Q 0x9e3779b9
  64
  65 /*----- Main code ---------------------------------------------------------*/
  66
  67 /* --- @rc5_init@ --- *
  68  *
  69  * Arguments:   @rc5_ctx *k@ = pointer to a key block
  70  *              @const void *sbuf@ = pointer to key material
  71  *              @size_t sz@ = size of the key material
  72  *
  73  * Returns:     ---
  74  *
  75  * Use:         Initializes an RC5 key block.
  76  */
  77
  78 void rc5_init(rc5_ctx *k, const void *sbuf, size_t sz)
  79 {
  80   uint32 *l;
  81   size_t w;
  82
  83   /* --- Set up the @L@ table --- *
  84    *
  85    * This is slightly unfortunately defined.
  86    */
  87
  88   KSZ_ASSERT(rc5, sz);
  89
  90   {
  91     int i;
  92     const octet *p = sbuf;
  93
  94     /* --- Create the buffer --- */
  95
  96     w = (sz + 3) / 4;
  97     l = XS_ALLOC(w * sizeof(uint32));
  98
  99     /* --- Extract the key material --- */
 100
 101     for (i = 0; sz > 3; i++) {
 102       l[i] = LOAD32_L(p);
 103       p += 4;
 104       sz -= 4;
 105     }
 106
 107     /* --- Fix up the tail end --- */
 108
 109     if (sz) {
 110       uint32 x = U8(*p++);
 111       if (sz > 1) x |= (U8(*p++) <<  8);
 112       if (sz > 2) x |= (U8(*p++) << 16);
 113       l[i] = x;
 114     }
 115   }
 116
 117   /* --- Initialize the @S@ table --- */
 118
 119   {
 120     int i;
 121
 122     k->s[0] = P;
 123     for (i = 1; i < T; i++)
 124       k->s[i] = k->s[i - 1] + Q;
 125   }
 126
 127   /* --- Mix in the key --- */
 128
 129   {
 130     int m = 3 * (w > T ? w : T);
 131     int i, j, c;
 132     uint32 a, b;
 133
 134     for (c = i = j = a = b = 0; c < m; c++) {
 135       uint32 x;
 136
 137       x = k->s[i] + a + b;
 138       k->s[i] = a = ROL32(x, 3);
 139       i++; if (i >= T) i = 0;
 140
 141       x = l[j] + a + b;
 142       l[j] = b = ROL32(x, a + b);
 143       j++; if (j >= w) j = 0;
 144     }
 145   }
 146
 147   memset(l, 0, w * sizeof(uint32));
 148   XS_FREE(l);
 149 }
 150
 151 /* --- @EROUND@, @DROUND@ --- */
 152
 153 #define EROUND(x, y, k) do {                                            \
 154   uint32 _x;                                                            \
 155   _x = x ^ y; x = ROL32(_x, y) + k[0];                                  \
 156   _x = y ^ x; y = ROL32(_x, x) + k[1];                                  \
 157   k += 2;                                                               \
 158 } while (0)
 159
 160 #define DROUND(x, y, k) do {                                            \
 161   uint32 _x;                                                            \
 162   k -= 2;                                                               \
 163   _x = y - k[1]; y = ROR32(_x, x) ^ x;                                  \
 164   _x = x - k[0]; x = ROR32(_x, y) ^ y;                                  \
 165 } while (0)
 166
 167 /* --- @EBLK@, @DBLK@ --- */
 168
 169 #define EBLK(a, b, c, d, k) do {                                        \
 170   uint32 _l, _r;                                                        \
 171   const uint32 *_k = (k)->s;                                            \
 172                                                                         \
 173   _l = (a) + _k[0];                                                     \
 174   _r = (b) + _k[1];                                                     \
 175   _k += 2;                                                              \
 176                                                                         \
 177   EROUND(_l, _r, _k);                                                   \
 178   EROUND(_l, _r, _k);                                                   \
 179   EROUND(_l, _r, _k);                                                   \
 180   EROUND(_l, _r, _k);                                                   \
 181   EROUND(_l, _r, _k);                                                   \
 182   EROUND(_l, _r, _k);                                                   \
 183   EROUND(_l, _r, _k);                                                   \
 184   EROUND(_l, _r, _k);                                                   \
 185   EROUND(_l, _r, _k);                                                   \
 186   EROUND(_l, _r, _k);                                                   \
 187   EROUND(_l, _r, _k);                                                   \
 188   EROUND(_l, _r, _k);                                                   \
 189   (c) = _l;                                                             \
 190   (d) = _r;                                                             \
 191 } while (0)
 192
 193 #define DBLK(a, b, c, d, k) do {                                        \
 194   uint32 _l, _r;                                                        \
 195   const uint32 *_k = (k)->s + T;                                        \
 196                                                                         \
 197   _l = (a);                                                             \
 198   _r = (b);                                                             \
 199                                                                         \
 200   DROUND(_l, _r, _k);                                                   \
 201   DROUND(_l, _r, _k);                                                   \
 202   DROUND(_l, _r, _k);                                                   \
 203   DROUND(_l, _r, _k);                                                   \
 204   DROUND(_l, _r, _k);                                                   \
 205   DROUND(_l, _r, _k);                                                   \
 206   DROUND(_l, _r, _k);                                                   \
 207   DROUND(_l, _r, _k);                                                   \
 208   DROUND(_l, _r, _k);                                                   \
 209   DROUND(_l, _r, _k);                                                   \
 210   DROUND(_l, _r, _k);                                                   \
 211   DROUND(_l, _r, _k);                                                   \
 212                                                                         \
 213   _k -= 2;                                                              \
 214   (d) = _r - _k[1];                                                     \
 215   (c) = _l - _k[0];                                                     \
 216 } while (0)
 217
 218 /* --- @rc5_eblk@, @rc5_dblk@ --- *
 219  *
 220  * Arguments:   @const rc5_ctx *k@ = pointer to RC5 context block
 221  *              @const uint32 s[2]@ = pointer to source block
 222  *              @uint32 *d[2]@ = pointer to destination block
 223  *
 224  * Returns:     ---
 225  *
 226  * Use:         Low level block encryption and decryption.
 227  */
 228
 229 void rc5_eblk(const rc5_ctx *k, const uint32 *s, uint32 *d)
 230 {
 231   EBLK(s[0], s[1], d[0], d[1], k);
 232 }
 233
 234 void rc5_dblk(const rc5_ctx *k, const uint32 *s, uint32 *d)
 235 {
 236   DBLK(s[0], s[1], d[0], d[1], k);
 237 }
 238
 239 /* --- Test rig --- */
 240
 241 BLKC_TEST(RC5, rc5)
 242
 243 /*----- That's all, folks -------------------------------------------------*/