crypto/idea/i_skey.c

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