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      1 /*
      2  * Copyright 1995-2020 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 }
    120