crypto/idea/i_skey.c

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