crypto/des/ofb64enc.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_locl.h"
  11
  12 /*
  13  * The input and output encrypted as though 64bit ofb 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 void DES_ofb64_encrypt(register const unsigned char *in,
  18                        register unsigned char *out, long length,
  19                        DES_key_schedule *schedule, DES_cblock *ivec, int *num)
  20 {
  21     register DES_LONG v0, v1, t;
  22     register int n = *num;
  23     register long l = length;
  24     DES_cblock d;
  25     register unsigned char *dp;
  26     DES_LONG ti[2];
  27     unsigned char *iv;
  28     int save = 0;
  29
  30     iv = &(*ivec)[0];
  31     c2l(iv, v0);
  32     c2l(iv, v1);
  33     ti[0] = v0;
  34     ti[1] = v1;
  35     dp = d;
  36     l2c(v0, dp);
  37     l2c(v1, dp);
  38     while (l--) {
  39         if (n == 0) {
  40             DES_encrypt1(ti, schedule, DES_ENCRYPT);
  41             dp = d;
  42             t = ti[0];
  43             l2c(t, dp);
  44             t = ti[1];
  45             l2c(t, dp);
  46             save++;
  47         }
  48         *(out++) = *(in++) ^ d[n];
  49         n = (n + 1) & 0x07;
  50     }
  51     if (save) {
  52         v0 = ti[0];
  53         v1 = ti[1];
  54         iv = &(*ivec)[0];
  55         l2c(v0, iv);
  56         l2c(v1, iv);
  57     }
  58     t = v0 = v1 = ti[0] = ti[1] = 0;
  59     *num = n;
  60 }