crypto/des/cfb_enc.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 "e_os.h"
  11 #include "des_locl.h"
  12 #include <assert.h>
  13
  14 /*
  15  * The input and output are loaded in multiples of 8 bits. What this means is
  16  * that if you hame numbits=12 and length=2 the first 12 bits will be
  17  * retrieved from the first byte and half the second.  The second 12 bits
  18  * will come from the 3rd and half the 4th byte.
  19  */
  20 /*
  21  * Until Aug 1 2003 this function did not correctly implement CFB-r, so it
  22  * will not be compatible with any encryption prior to that date. Ben.
  23  */
  24 void DES_cfb_encrypt(const unsigned char *in, unsigned char *out, int numbits,
  25                      long length, DES_key_schedule *schedule,
  26                      DES_cblock *ivec, int enc)
  27 {
  28     register DES_LONG d0, d1, v0, v1;
  29     register unsigned long l = length;
  30     register int num = numbits / 8, n = (numbits + 7) / 8, i, rem =
  31         numbits % 8;
  32     DES_LONG ti[2];
  33     unsigned char *iv;
  34 #ifndef L_ENDIAN
  35     unsigned char ovec[16];
  36 #else
  37     unsigned int sh[4];
  38     unsigned char *ovec = (unsigned char *)sh;
  39
  40     /* I kind of count that compiler optimizes away this assertion, */
  41     assert(sizeof(sh[0]) == 4); /* as this holds true for all, */
  42     /* but 16-bit platforms...      */
  43
  44 #endif
  45
  46     if (numbits <= 0 || numbits > 64)
  47         return;
  48     iv = &(*ivec)[0];
  49     c2l(iv, v0);
  50     c2l(iv, v1);
  51     if (enc) {
  52         while (l >= (unsigned long)n) {
  53             l -= n;
  54             ti[0] = v0;
  55             ti[1] = v1;
  56             DES_encrypt1((DES_LONG *)ti, schedule, DES_ENCRYPT);
  57             c2ln(in, d0, d1, n);
  58             in += n;
  59             d0 ^= ti[0];
  60             d1 ^= ti[1];
  61             l2cn(d0, d1, out, n);
  62             out += n;
  63             /*
  64              * 30-08-94 - eay - changed because l>>32 and l<<32 are bad under
  65              * gcc :-(
  66              */
  67             if (numbits == 32) {
  68                 v0 = v1;
  69                 v1 = d0;
  70             } else if (numbits == 64) {
  71                 v0 = d0;
  72                 v1 = d1;
  73             } else {
  74 #ifndef L_ENDIAN
  75                 iv = &ovec[0];
  76                 l2c(v0, iv);
  77                 l2c(v1, iv);
  78                 l2c(d0, iv);
  79                 l2c(d1, iv);
  80 #else
  81                 sh[0] = v0, sh[1] = v1, sh[2] = d0, sh[3] = d1;
  82 #endif
  83                 if (rem == 0)
  84                     memmove(ovec, ovec + num, 8);
  85                 else
  86                     for (i = 0; i < 8; ++i)
  87                         ovec[i] = ovec[i + num] << rem |
  88                             ovec[i + num + 1] >> (8 - rem);
  89 #ifdef L_ENDIAN
  90                 v0 = sh[0], v1 = sh[1];
  91 #else
  92                 iv = &ovec[0];
  93                 c2l(iv, v0);
  94                 c2l(iv, v1);
  95 #endif
  96             }
  97         }
  98     } else {
  99         while (l >= (unsigned long)n) {
 100             l -= n;
 101             ti[0] = v0;
 102             ti[1] = v1;
 103             DES_encrypt1((DES_LONG *)ti, schedule, DES_ENCRYPT);
 104             c2ln(in, d0, d1, n);
 105             in += n;
 106             /*
 107              * 30-08-94 - eay - changed because l>>32 and l<<32 are bad under
 108              * gcc :-(
 109              */
 110             if (numbits == 32) {
 111                 v0 = v1;
 112                 v1 = d0;
 113             } else if (numbits == 64) {
 114                 v0 = d0;
 115                 v1 = d1;
 116             } else {
 117 #ifndef L_ENDIAN
 118                 iv = &ovec[0];
 119                 l2c(v0, iv);
 120                 l2c(v1, iv);
 121                 l2c(d0, iv);
 122                 l2c(d1, iv);
 123 #else
 124                 sh[0] = v0, sh[1] = v1, sh[2] = d0, sh[3] = d1;
 125 #endif
 126                 if (rem == 0)
 127                     memmove(ovec, ovec + num, 8);
 128                 else
 129                     for (i = 0; i < 8; ++i)
 130                         ovec[i] = ovec[i + num] << rem |
 131                             ovec[i + num + 1] >> (8 - rem);
 132 #ifdef L_ENDIAN
 133                 v0 = sh[0], v1 = sh[1];
 134 #else
 135                 iv = &ovec[0];
 136                 c2l(iv, v0);
 137                 c2l(iv, v1);
 138 #endif
 139             }
 140             d0 ^= ti[0];
 141             d1 ^= ti[1];
 142             l2cn(d0, d1, out, n);
 143             out += n;
 144         }
 145     }
 146     iv = &(*ivec)[0];
 147     l2c(v0, iv);
 148     l2c(v1, iv);
 149     v0 = v1 = d0 = d1 = ti[0] = ti[1] = 0;
 150 }