crypto/idea/i_skey.c

   1 /*
   2  * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <openssl/idea.h>
  11 #include "idea_local.h"
  12
  13 static IDEA_INT inverse(unsigned int xin);
  14 void IDEA_set_encrypt_key(const unsigned char *key, IDEA_KEY_SCHEDULE *ks)
  15 {
  16     int i;
  17     register IDEA_INT *kt, *kf, r0, r1, r2;
  18
  19     kt = &(ks->data[0][0]);
  20     n2s(key, kt[0]);
  21     n2s(key, kt[1]);
  22     n2s(key, kt[2]);
  23     n2s(key, kt[3]);
  24     n2s(key, kt[4]);
  25     n2s(key, kt[5]);
  26     n2s(key, kt[6]);
  27     n2s(key, kt[7]);
  28
  29     kf = kt;
  30     kt += 8;
  31     for (i = 0; i < 6; i++) {
  32         r2 = kf[1];
  33         r1 = kf[2];
  34         *(kt++) = ((r2 << 9) | (r1 >> 7)) & 0xffff;
  35         r0 = kf[3];
  36         *(kt++) = ((r1 << 9) | (r0 >> 7)) & 0xffff;
  37         r1 = kf[4];
  38         *(kt++) = ((r0 << 9) | (r1 >> 7)) & 0xffff;
  39         r0 = kf[5];
  40         *(kt++) = ((r1 << 9) | (r0 >> 7)) & 0xffff;
  41         r1 = kf[6];
  42         *(kt++) = ((r0 << 9) | (r1 >> 7)) & 0xffff;
  43         r0 = kf[7];
  44         *(kt++) = ((r1 << 9) | (r0 >> 7)) & 0xffff;
  45         r1 = kf[0];
  46         if (i >= 5)
  47             break;
  48         *(kt++) = ((r0 << 9) | (r1 >> 7)) & 0xffff;
  49         *(kt++) = ((r1 << 9) | (r2 >> 7)) & 0xffff;
  50         kf += 8;
  51     }
  52 }
  53
  54 void IDEA_set_decrypt_key(IDEA_KEY_SCHEDULE *ek, IDEA_KEY_SCHEDULE *dk)
  55 {
  56     int r;
  57     register IDEA_INT *fp, *tp, t;
  58
  59     tp = &(dk->data[0][0]);
  60     fp = &(ek->data[8][0]);
  61     for (r = 0; r < 9; r++) {
  62         *(tp++) = inverse(fp[0]);
  63         *(tp++) = ((int)(0x10000L - fp[2]) & 0xffff);
  64         *(tp++) = ((int)(0x10000L - fp[1]) & 0xffff);
  65         *(tp++) = inverse(fp[3]);
  66         if (r == 8)
  67             break;
  68         fp -= 6;
  69         *(tp++) = fp[4];
  70         *(tp++) = fp[5];
  71     }
  72
  73     tp = &(dk->data[0][0]);
  74     t = tp[1];
  75     tp[1] = tp[2];
  76     tp[2] = t;
  77
  78     t = tp[49];
  79     tp[49] = tp[50];
  80     tp[50] = t;
  81 }
  82
  83 /* taken directly from the 'paper' I'll have a look at it later */
  84 static IDEA_INT inverse(unsigned int xin)
  85 {
  86     long n1, n2, q, r, b1, b2, t;
  87
  88     if (xin == 0)
  89         b2 = 0;
  90     else {
  91         n1 = 0x10001;
  92         n2 = xin;
  93         b2 = 1;
  94         b1 = 0;
  95
  96         do {
  97             r = (n1 % n2);
  98             q = (n1 - r) / n2;
  99             if (r == 0) {
 100                 if (b2 < 0)
 101                     b2 = 0x10001 + b2;
 102             } else {
 103                 n1 = n2;
 104                 n2 = r;
 105                 t = b2;
 106                 b2 = b1 - q * b2;
 107                 b1 = t;
 108             }
 109         } while (r != 0);
 110     }
 111     return (IDEA_INT)b2;
 112 }