crypto/des/cfb64enc.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 "des_local.h"
  11
  12 /*
  13  * The input and output encrypted as though 64bit cfb mode is being used.
  14  * The extra state information to record how much of the 64bit block we have
  15  * used is contained in *num;
  16  */
  17
  18 void DES_cfb64_encrypt(const unsigned char *in, unsigned char *out,
  19                        long length, DES_key_schedule *schedule,
  20                        DES_cblock *ivec, int *num, int enc)
  21 {
  22     register DES_LONG v0, v1;
  23     register long l = length;
  24     register int n = *num;
  25     DES_LONG ti[2];
  26     unsigned char *iv, c, cc;
  27
  28     iv = &(*ivec)[0];
  29     if (enc) {
  30         while (l--) {
  31             if (n == 0) {
  32                 c2l(iv, v0);
  33                 ti[0] = v0;
  34                 c2l(iv, v1);
  35                 ti[1] = v1;
  36                 DES_encrypt1(ti, schedule, DES_ENCRYPT);
  37                 iv = &(*ivec)[0];
  38                 v0 = ti[0];
  39                 l2c(v0, iv);
  40                 v0 = ti[1];
  41                 l2c(v0, iv);
  42                 iv = &(*ivec)[0];
  43             }
  44             c = *(in++) ^ iv[n];
  45             *(out++) = c;
  46             iv[n] = c;
  47             n = (n + 1) & 0x07;
  48         }
  49     } else {
  50         while (l--) {
  51             if (n == 0) {
  52                 c2l(iv, v0);
  53                 ti[0] = v0;
  54                 c2l(iv, v1);
  55                 ti[1] = v1;
  56                 DES_encrypt1(ti, schedule, DES_ENCRYPT);
  57                 iv = &(*ivec)[0];
  58                 v0 = ti[0];
  59                 l2c(v0, iv);
  60                 v0 = ti[1];
  61                 l2c(v0, iv);
  62                 iv = &(*ivec)[0];
  63             }
  64             cc = *(in++);
  65             c = iv[n];
  66             iv[n] = cc;
  67             *(out++) = c ^ cc;
  68             n = (n + 1) & 0x07;
  69         }
  70     }
  71     v0 = v1 = ti[0] = ti[1] = c = cc = 0;
  72     *num = n;
  73 }