crypto/cast/c_ofb64.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 /*
  11  * CAST low level APIs are deprecated for public use, but still ok for
  12  * internal use.
  13  */
  14 #include "internal/deprecated.h"
  15
  16 #include <openssl/cast.h>
  17 #include "cast_local.h"
  18
  19 /*
  20  * The input and output encrypted as though 64bit ofb mode is being used.
  21  * The extra state information to record how much of the 64bit block we have
  22  * used is contained in *num;
  23  */
  24 void CAST_ofb64_encrypt(const unsigned char *in, unsigned char *out,
  25                         long length, const CAST_KEY *schedule,
  26                         unsigned char *ivec, int *num)
  27 {
  28     register CAST_LONG v0, v1, t;
  29     register int n = *num;
  30     register long l = length;
  31     unsigned char d[8];
  32     register char *dp;
  33     CAST_LONG ti[2];
  34     unsigned char *iv;
  35     int save = 0;
  36
  37     iv = ivec;
  38     n2l(iv, v0);
  39     n2l(iv, v1);
  40     ti[0] = v0;
  41     ti[1] = v1;
  42     dp = (char *)d;
  43     l2n(v0, dp);
  44     l2n(v1, dp);
  45     while (l--) {
  46         if (n == 0) {
  47             CAST_encrypt((CAST_LONG *)ti, schedule);
  48             dp = (char *)d;
  49             t = ti[0];
  50             l2n(t, dp);
  51             t = ti[1];
  52             l2n(t, dp);
  53             save++;
  54         }
  55         *(out++) = *(in++) ^ d[n];
  56         n = (n + 1) & 0x07;
  57     }
  58     if (save) {
  59         v0 = ti[0];
  60         v1 = ti[1];
  61         iv = ivec;
  62         l2n(v0, iv);
  63         l2n(v1, iv);
  64     }
  65     t = v0 = v1 = ti[0] = ti[1] = 0;
  66     *num = n;
  67 }