crypto/des/cfb_enc.c

   1 /*
   2  * Copyright 1995-2022 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  * DES low level APIs are deprecated for public use, but still ok for internal
  12  * use.
  13  */
  14 #include "internal/deprecated.h"
  15
  16 #include "internal/e_os.h"
  17 #include "des_local.h"
  18 #include <assert.h>
  19
  20 /*
  21  * The input and output are loaded in multiples of 8 bits. What this means is
  22  * that if you hame numbits=12 and length=2 the first 12 bits will be
  23  * retrieved from the first byte and half the second.  The second 12 bits
  24  * will come from the 3rd and half the 4th byte.
  25  */
  26 /*
  27  * Until Aug 1 2003 this function did not correctly implement CFB-r, so it
  28  * will not be compatible with any encryption prior to that date. Ben.
  29  */
  30 void DES_cfb_encrypt(const unsigned char *in, unsigned char *out, int numbits,
  31                      long length, DES_key_schedule *schedule,
  32                      DES_cblock *ivec, int enc)
  33 {
  34     register DES_LONG d0, d1, v0, v1;
  35     register unsigned long l = length;
  36     register int num = numbits / 8, n = (numbits + 7) / 8, i, rem =
  37         numbits % 8;
  38     DES_LONG ti[2];
  39     unsigned char *iv;
  40 #ifndef L_ENDIAN
  41     unsigned char ovec[16];
  42 #else
  43     unsigned int sh[4];
  44     unsigned char *ovec = (unsigned char *)sh;
  45
  46     /* I kind of count that compiler optimizes away this assertion, */
  47     assert(sizeof(sh[0]) == 4); /* as this holds true for all, */
  48     /* but 16-bit platforms...      */
  49
  50 #endif
  51
  52     if (numbits <= 0 || numbits > 64)
  53         return;
  54     iv = &(*ivec)[0];
  55     c2l(iv, v0);
  56     c2l(iv, v1);
  57     if (enc) {
  58         while (l >= (unsigned long)n) {
  59             l -= n;
  60             ti[0] = v0;
  61             ti[1] = v1;
  62             DES_encrypt1((DES_LONG *)ti, schedule, DES_ENCRYPT);
  63             c2ln(in, d0, d1, n);
  64             in += n;
  65             d0 ^= ti[0];
  66             d1 ^= ti[1];
  67             l2cn(d0, d1, out, n);
  68             out += n;
  69             /*
  70              * 30-08-94 - eay - changed because l>>32 and l<<32 are bad under
  71              * gcc :-(
  72              */
  73             if (numbits == 32) {
  74                 v0 = v1;
  75                 v1 = d0;
  76             } else if (numbits == 64) {
  77                 v0 = d0;
  78                 v1 = d1;
  79             } else {
  80 #ifndef L_ENDIAN
  81                 iv = &ovec[0];
  82                 l2c(v0, iv);
  83                 l2c(v1, iv);
  84                 l2c(d0, iv);
  85                 l2c(d1, iv);
  86 #else
  87                 sh[0] = v0, sh[1] = v1, sh[2] = d0, sh[3] = d1;
  88 #endif
  89                 if (rem == 0)
  90                     memmove(ovec, ovec + num, 8);
  91                 else
  92                     for (i = 0; i < 8; ++i)
  93                         ovec[i] = ovec[i + num] << rem |
  94                             ovec[i + num + 1] >> (8 - rem);
  95 #ifdef L_ENDIAN
  96                 v0 = sh[0], v1 = sh[1];
  97 #else
  98                 iv = &ovec[0];
  99                 c2l(iv, v0);
 100                 c2l(iv, v1);
 101 #endif
 102             }
 103         }
 104     } else {
 105         while (l >= (unsigned long)n) {
 106             l -= n;
 107             ti[0] = v0;
 108             ti[1] = v1;
 109             DES_encrypt1((DES_LONG *)ti, schedule, DES_ENCRYPT);
 110             c2ln(in, d0, d1, n);
 111             in += n;
 112             /*
 113              * 30-08-94 - eay - changed because l>>32 and l<<32 are bad under
 114              * gcc :-(
 115              */
 116             if (numbits == 32) {
 117                 v0 = v1;
 118                 v1 = d0;
 119             } else if (numbits == 64) {
 120                 v0 = d0;
 121                 v1 = d1;
 122             } else {
 123 #ifndef L_ENDIAN
 124                 iv = &ovec[0];
 125                 l2c(v0, iv);
 126                 l2c(v1, iv);
 127                 l2c(d0, iv);
 128                 l2c(d1, iv);
 129 #else
 130                 sh[0] = v0, sh[1] = v1, sh[2] = d0, sh[3] = d1;
 131 #endif
 132                 if (rem == 0)
 133                     memmove(ovec, ovec + num, 8);
 134                 else
 135                     for (i = 0; i < 8; ++i)
 136                         ovec[i] = ovec[i + num] << rem |
 137                             ovec[i + num + 1] >> (8 - rem);
 138 #ifdef L_ENDIAN
 139                 v0 = sh[0], v1 = sh[1];
 140 #else
 141                 iv = &ovec[0];
 142                 c2l(iv, v0);
 143                 c2l(iv, v1);
 144 #endif
 145             }
 146             d0 ^= ti[0];
 147             d1 ^= ti[1];
 148             l2cn(d0, d1, out, n);
 149             out += n;
 150         }
 151     }
 152     iv = &(*ivec)[0];
 153     l2c(v0, iv);
 154     l2c(v1, iv);
 155     v0 = v1 = d0 = d1 = ti[0] = ti[1] = 0;
 156 }