crypto/des/cfb_enc.c

   1 /* crypto/des/cfb_enc.c */
   2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   3  * All rights reserved.
   4  *
   5  * This package is an SSL implementation written
   6  * by Eric Young (eay@cryptsoft.com).
   7  * The implementation was written so as to conform with Netscapes SSL.
   8  *
   9  * This library is free for commercial and non-commercial use as long as
  10  * the following conditions are aheared to.  The following conditions
  11  * apply to all code found in this distribution, be it the RC4, RSA,
  12  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  13  * included with this distribution is covered by the same copyright terms
  14  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  15  *
  16  * Copyright remains Eric Young's, and as such any Copyright notices in
  17  * the code are not to be removed.
  18  * If this package is used in a product, Eric Young should be given attribution
  19  * as the author of the parts of the library used.
  20  * This can be in the form of a textual message at program startup or
  21  * in documentation (online or textual) provided with the package.
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  * 1. Redistributions of source code must retain the copyright
  27  *    notice, this list of conditions and the following disclaimer.
  28  * 2. Redistributions in binary form must reproduce the above copyright
  29  *    notice, this list of conditions and the following disclaimer in the
  30  *    documentation and/or other materials provided with the distribution.
  31  * 3. All advertising materials mentioning features or use of this software
  32  *    must display the following acknowledgement:
  33  *    "This product includes cryptographic software written by
  34  *     Eric Young (eay@cryptsoft.com)"
  35  *    The word 'cryptographic' can be left out if the rouines from the library
  36  *    being used are not cryptographic related :-).
  37  * 4. If you include any Windows specific code (or a derivative thereof) from
  38  *    the apps directory (application code) you must include an acknowledgement:
  39  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  40  *
  41  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  42  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  44  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  45  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  46  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  47  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  49  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  50  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  51  * SUCH DAMAGE.
  52  *
  53  * The licence and distribution terms for any publically available version or
  54  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  55  * copied and put under another distribution licence
  56  * [including the GNU Public Licence.]
  57  */
  58
  59 #include "e_os.h"
  60 #include "des_locl.h"
  61 #include <assert.h>
  62
  63 /*
  64  * The input and output are loaded in multiples of 8 bits. What this means is
  65  * that if you hame numbits=12 and length=2 the first 12 bits will be
  66  * retrieved from the first byte and half the second.  The second 12 bits
  67  * will come from the 3rd and half the 4th byte.
  68  */
  69 /*
  70  * Until Aug 1 2003 this function did not correctly implement CFB-r, so it
  71  * will not be compatible with any encryption prior to that date. Ben.
  72  */
  73 void DES_cfb_encrypt(const unsigned char *in, unsigned char *out, int numbits,
  74                      long length, DES_key_schedule *schedule,
  75                      DES_cblock *ivec, int enc)
  76 {
  77     register DES_LONG d0, d1, v0, v1;
  78     register unsigned long l = length;
  79     register int num = numbits / 8, n = (numbits + 7) / 8, i, rem =
  80         numbits % 8;
  81     DES_LONG ti[2];
  82     unsigned char *iv;
  83 #ifndef L_ENDIAN
  84     unsigned char ovec[16];
  85 #else
  86     unsigned int sh[4];
  87     unsigned char *ovec = (unsigned char *)sh;
  88
  89     /* I kind of count that compiler optimizes away this assertioni, */
  90     assert(sizeof(sh[0]) == 4); /* as this holds true for all, */
  91     /* but 16-bit platforms...      */
  92
  93 #endif
  94
  95     if (numbits <= 0 || numbits > 64)
  96         return;
  97     iv = &(*ivec)[0];
  98     c2l(iv, v0);
  99     c2l(iv, v1);
 100     if (enc) {
 101         while (l >= (unsigned long)n) {
 102             l -= n;
 103             ti[0] = v0;
 104             ti[1] = v1;
 105             DES_encrypt1((DES_LONG *)ti, schedule, DES_ENCRYPT);
 106             c2ln(in, d0, d1, n);
 107             in += n;
 108             d0 ^= ti[0];
 109             d1 ^= ti[1];
 110             l2cn(d0, d1, out, n);
 111             out += 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         }
 147     } else {
 148         while (l >= (unsigned long)n) {
 149             l -= n;
 150             ti[0] = v0;
 151             ti[1] = v1;
 152             DES_encrypt1((DES_LONG *)ti, schedule, DES_ENCRYPT);
 153             c2ln(in, d0, d1, n);
 154             in += n;
 155             /*
 156              * 30-08-94 - eay - changed because l>>32 and l<<32 are bad under
 157              * gcc :-(
 158              */
 159             if (numbits == 32) {
 160                 v0 = v1;
 161                 v1 = d0;
 162             } else if (numbits == 64) {
 163                 v0 = d0;
 164                 v1 = d1;
 165             } else {
 166 #ifndef L_ENDIAN
 167                 iv = &ovec[0];
 168                 l2c(v0, iv);
 169                 l2c(v1, iv);
 170                 l2c(d0, iv);
 171                 l2c(d1, iv);
 172 #else
 173                 sh[0] = v0, sh[1] = v1, sh[2] = d0, sh[3] = d1;
 174 #endif
 175                 if (rem == 0)
 176                     memmove(ovec, ovec + num, 8);
 177                 else
 178                     for (i = 0; i < 8; ++i)
 179                         ovec[i] = ovec[i + num] << rem |
 180                             ovec[i + num + 1] >> (8 - rem);
 181 #ifdef L_ENDIAN
 182                 v0 = sh[0], v1 = sh[1];
 183 #else
 184                 iv = &ovec[0];
 185                 c2l(iv, v0);
 186                 c2l(iv, v1);
 187 #endif
 188             }
 189             d0 ^= ti[0];
 190             d1 ^= ti[1];
 191             l2cn(d0, d1, out, n);
 192             out += n;
 193         }
 194     }
 195     iv = &(*ivec)[0];
 196     l2c(v0, iv);
 197     l2c(v1, iv);
 198     v0 = v1 = d0 = d1 = ti[0] = ti[1] = 0;
 199 }