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 /*
  11  * IDEA low level APIs are deprecated for public use, but still ok for internal
  12  * use where we're using them to implement the higher level EVP interface, as is
  13  * the case here.
  14  */
  15 #include "internal/deprecated.h"
  16
  17 #include <openssl/idea.h>
  18 #include "idea_local.h"
  19
  20 static IDEA_INT inverse(unsigned int xin);
  21 void IDEA_set_encrypt_key(const unsigned char *key, IDEA_KEY_SCHEDULE *ks)
  22 {
  23     int i;
  24     register IDEA_INT *kt, *kf, r0, r1, r2;
  25
  26     kt = &(ks->data[0][0]);
  27     n2s(key, kt[0]);
  28     n2s(key, kt[1]);
  29     n2s(key, kt[2]);
  30     n2s(key, kt[3]);
  31     n2s(key, kt[4]);
  32     n2s(key, kt[5]);
  33     n2s(key, kt[6]);
  34     n2s(key, kt[7]);
  35
  36     kf = kt;
  37     kt += 8;
  38     for (i = 0; i < 6; i++) {
  39         r2 = kf[1];
  40         r1 = kf[2];
  41         *(kt++) = ((r2 << 9) | (r1 >> 7)) & 0xffff;
  42         r0 = kf[3];
  43         *(kt++) = ((r1 << 9) | (r0 >> 7)) & 0xffff;
  44         r1 = kf[4];
  45         *(kt++) = ((r0 << 9) | (r1 >> 7)) & 0xffff;
  46         r0 = kf[5];
  47         *(kt++) = ((r1 << 9) | (r0 >> 7)) & 0xffff;
  48         r1 = kf[6];
  49         *(kt++) = ((r0 << 9) | (r1 >> 7)) & 0xffff;
  50         r0 = kf[7];
  51         *(kt++) = ((r1 << 9) | (r0 >> 7)) & 0xffff;
  52         r1 = kf[0];
  53         if (i >= 5)
  54             break;
  55         *(kt++) = ((r0 << 9) | (r1 >> 7)) & 0xffff;
  56         *(kt++) = ((r1 << 9) | (r2 >> 7)) & 0xffff;
  57         kf += 8;
  58     }
  59 }
  60
  61 void IDEA_set_decrypt_key(IDEA_KEY_SCHEDULE *ek, IDEA_KEY_SCHEDULE *dk)
  62 {
  63     int r;
  64     register IDEA_INT *fp, *tp, t;
  65
  66     tp = &(dk->data[0][0]);
  67     fp = &(ek->data[8][0]);
  68     for (r = 0; r < 9; r++) {
  69         *(tp++) = inverse(fp[0]);
  70         *(tp++) = ((int)(0x10000L - fp[2]) & 0xffff);
  71         *(tp++) = ((int)(0x10000L - fp[1]) & 0xffff);
  72         *(tp++) = inverse(fp[3]);
  73         if (r == 8)
  74             break;
  75         fp -= 6;
  76         *(tp++) = fp[4];
  77         *(tp++) = fp[5];
  78     }
  79
  80     tp = &(dk->data[0][0]);
  81     t = tp[1];
  82     tp[1] = tp[2];
  83     tp[2] = t;
  84
  85     t = tp[49];
  86     tp[49] = tp[50];
  87     tp[50] = t;
  88 }
  89
  90 /* taken directly from the 'paper' I'll have a look at it later */
  91 static IDEA_INT inverse(unsigned int xin)
  92 {
  93     long n1, n2, q, r, b1, b2, t;
  94
  95     if (xin == 0)
  96         b2 = 0;
  97     else {
  98         n1 = 0x10001;
  99         n2 = xin;
 100         b2 = 1;
 101         b1 = 0;
 102
 103         do {
 104             r = (n1 % n2);
 105             q = (n1 - r) / n2;
 106             if (r == 0) {
 107                 if (b2 < 0)
 108                     b2 = 0x10001 + b2;
 109             } else {
 110                 n1 = n2;
 111                 n2 = r;
 112                 t = b2;
 113                 b2 = b1 - q * b2;
 114                 b1 = t;
 115             }
 116         } while (r != 0);
 117     }
 118     return (IDEA_INT)b2;
 119 }