cscrypt/i_skey.c

   1 //FIXME Not checked on threadsafety yet; after checking please remove this line
   2 /* crypto/idea/i_skey.c */
   3 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   4  * All rights reserved.
   5  *
   6  * This package is an SSL implementation written
   7  * by Eric Young (eay@cryptsoft.com).
   8  * The implementation was written so as to conform with Netscapes SSL.
   9  *
  10  * This library is free for commercial and non-commercial use as long as
  11  * the following conditions are aheared to.  The following conditions
  12  * apply to all code found in this distribution, be it the RC4, RSA,
  13  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  14  * included with this distribution is covered by the same copyright terms
  15  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  16  *
  17  * Copyright remains Eric Young's, and as such any Copyright notices in
  18  * the code are not to be removed.
  19  * If this package is used in a product, Eric Young should be given attribution
  20  * as the author of the parts of the library used.
  21  * This can be in the form of a textual message at program startup or
  22  * in documentation (online or textual) provided with the package.
  23  *
  24  * Redistribution and use in source and binary forms, with or without
  25  * modification, are permitted provided that the following conditions
  26  * are met:
  27  * 1. Redistributions of source code must retain the copyright
  28  *    notice, this list of conditions and the following disclaimer.
  29  * 2. Redistributions in binary form must reproduce the above copyright
  30  *    notice, this list of conditions and the following disclaimer in the
  31  *    documentation and/or other materials provided with the distribution.
  32  * 3. All advertising materials mentioning features or use of this software
  33  *    must display the following acknowledgement:
  34  *    "This product includes cryptographic software written by
  35  *     Eric Young (eay@cryptsoft.com)"
  36  *    The word 'cryptographic' can be left out if the rouines from the library
  37  *    being used are not cryptographic related :-).
  38  * 4. If you include any Windows specific code (or a derivative thereof) from
  39  *    the apps directory (application code) you must include an acknowledgement:
  40  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  41  *
  42  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  43  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  44  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  45  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  46  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  47  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  48  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  49  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  50  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  51  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  52  * SUCH DAMAGE.
  53  *
  54  * The license and distribution terms for any publically available version or
  55  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  56  * copied and put under another distribution license
  57  * [including the GNU Public License.]
  58  */
  59
  60 #include "idea.h"
  61 #include "idea_lcl.h"
  62
  63 static IDEA_INT inverse(unsigned int xin);
  64 void idea_set_encrypt_key(const unsigned char *key, IDEA_KEY_SCHEDULE *ks)
  65 {
  66         int i;
  67         register IDEA_INT *kt, *kf, r0, r1, r2;
  68
  69         kt = &(ks->data[0][0]);
  70         n2s(key, kt[0]);
  71         n2s(key, kt[1]);
  72         n2s(key, kt[2]);
  73         n2s(key, kt[3]);
  74         n2s(key, kt[4]);
  75         n2s(key, kt[5]);
  76         n2s(key, kt[6]);
  77         n2s(key, kt[7]);
  78
  79         kf = kt;
  80         kt += 8;
  81         for(i = 0; i < 6; i++)
  82         {
  83                 r2 = kf[1];
  84                 r1 = kf[2];
  85                 *(kt++) = ((r2 << 9) | (r1 >> 7)) & 0xffff;
  86                 r0 = kf[3];
  87                 *(kt++) = ((r1 << 9) | (r0 >> 7)) & 0xffff;
  88                 r1 = kf[4];
  89                 *(kt++) = ((r0 << 9) | (r1 >> 7)) & 0xffff;
  90                 r0 = kf[5];
  91                 *(kt++) = ((r1 << 9) | (r0 >> 7)) & 0xffff;
  92                 r1 = kf[6];
  93                 *(kt++) = ((r0 << 9) | (r1 >> 7)) & 0xffff;
  94                 r0 = kf[7];
  95                 *(kt++) = ((r1 << 9) | (r0 >> 7)) & 0xffff;
  96                 r1 = kf[0];
  97                 if(i >= 5) { break; }
  98                 *(kt++) = ((r0 << 9) | (r1 >> 7)) & 0xffff;
  99                 *(kt++) = ((r1 << 9) | (r2 >> 7)) & 0xffff;
 100                 kf += 8;
 101         }
 102 }
 103
 104 void idea_set_decrypt_key(IDEA_KEY_SCHEDULE *ek, IDEA_KEY_SCHEDULE *dk)
 105 {
 106         int r;
 107         register IDEA_INT *fp, *tp, t;
 108
 109         tp = &(dk->data[0][0]);
 110         fp = &(ek->data[8][0]);
 111         for(r = 0; r < 9; r++)
 112         {
 113                 *(tp++) = inverse(fp[0]);
 114                 *(tp++) = ((int)(0x10000L - fp[2]) & 0xffff);
 115                 *(tp++) = ((int)(0x10000L - fp[1]) & 0xffff);
 116                 *(tp++) = inverse(fp[3]);
 117                 if(r == 8) { break; }
 118                 fp -= 6;
 119                 *(tp++) = fp[4];
 120                 *(tp++) = fp[5];
 121         }
 122
 123         tp = &(dk->data[0][0]);
 124         t = tp[1];
 125         tp[1] = tp[2];
 126         tp[2] = t;
 127
 128         t = tp[49];
 129         tp[49] = tp[50];
 130         tp[50] = t;
 131 }
 132
 133 /* taken directly from the 'paper' I'll have a look at it later */
 134 static IDEA_INT inverse(unsigned int xin)
 135 {
 136         long n1, n2, q, r, b1, b2, t;
 137
 138         if(xin == 0)
 139                 { b2 = 0; }
 140         else
 141         {
 142                 n1 = 0x10001;
 143                 n2 = xin;
 144                 b2 = 1;
 145                 b1 = 0;
 146
 147                 do
 148                 {
 149                         r = (n1 % n2);
 150                         q = (n1 - r) / n2;
 151                         if(r == 0)
 152                         {
 153                                 if(b2 < 0) { b2 = 0x10001 + b2; }
 154                         }
 155                         else
 156                         {
 157                                 n1 = n2;
 158                                 n2 = r;
 159                                 t = b2;
 160                                 b2 = b1 - q * b2;
 161                                 b1 = t;
 162                         }
 163                 }
 164                 while(r != 0);
 165         }
 166         return ((IDEA_INT)b2);
 167 }