crypto/des/ofb_enc.c

   1 /* crypto/des/ofb_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 "des_locl.h"
  60
  61 /*
  62  * The input and output are loaded in multiples of 8 bits. What this means is
  63  * that if you hame numbits=12 and length=2 the first 12 bits will be
  64  * retrieved from the first byte and half the second.  The second 12 bits
  65  * will come from the 3rd and half the 4th byte.
  66  */
  67 void DES_ofb_encrypt(const unsigned char *in, unsigned char *out, int numbits,
  68                      long length, DES_key_schedule *schedule,
  69                      DES_cblock *ivec)
  70 {
  71     register DES_LONG d0, d1, vv0, vv1, v0, v1, n = (numbits + 7) / 8;
  72     register DES_LONG mask0, mask1;
  73     register long l = length;
  74     register int num = numbits;
  75     DES_LONG ti[2];
  76     unsigned char *iv;
  77
  78     if (num > 64)
  79         return;
  80     if (num > 32) {
  81         mask0 = 0xffffffffL;
  82         if (num >= 64)
  83             mask1 = mask0;
  84         else
  85             mask1 = (1L << (num - 32)) - 1;
  86     } else {
  87         if (num == 32)
  88             mask0 = 0xffffffffL;
  89         else
  90             mask0 = (1L << num) - 1;
  91         mask1 = 0x00000000L;
  92     }
  93
  94     iv = &(*ivec)[0];
  95     c2l(iv, v0);
  96     c2l(iv, v1);
  97     ti[0] = v0;
  98     ti[1] = v1;
  99     while (l-- > 0) {
 100         ti[0] = v0;
 101         ti[1] = v1;
 102         DES_encrypt1((DES_LONG *)ti, schedule, DES_ENCRYPT);
 103         vv0 = ti[0];
 104         vv1 = ti[1];
 105         c2ln(in, d0, d1, n);
 106         in += n;
 107         d0 = (d0 ^ vv0) & mask0;
 108         d1 = (d1 ^ vv1) & mask1;
 109         l2cn(d0, d1, out, n);
 110         out += n;
 111
 112         if (num == 32) {
 113             v0 = v1;
 114             v1 = vv0;
 115         } else if (num == 64) {
 116             v0 = vv0;
 117             v1 = vv1;
 118         } else if (num > 32) {  /* && num != 64 */
 119             v0 = ((v1 >> (num - 32)) | (vv0 << (64 - num))) & 0xffffffffL;
 120             v1 = ((vv0 >> (num - 32)) | (vv1 << (64 - num))) & 0xffffffffL;
 121         } else {                /* num < 32 */
 122
 123             v0 = ((v0 >> num) | (v1 << (32 - num))) & 0xffffffffL;
 124             v1 = ((v1 >> num) | (vv0 << (32 - num))) & 0xffffffffL;
 125         }
 126     }
 127     iv = &(*ivec)[0];
 128     l2c(v0, iv);
 129     l2c(v1, iv);
 130     v0 = v1 = d0 = d1 = ti[0] = ti[1] = vv0 = vv1 = 0;
 131 }