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      1 /*
      2  * Copyright 1995-2020 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 cfb 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 
     25 void CAST_cfb64_encrypt(const unsigned char *in, unsigned char *out,
     26     long length, const CAST_KEY *schedule,
     27     unsigned char *ivec, int *num, int enc)
     28 {
     29     register CAST_LONG v0, v1, t;
     30     register int n = *num;
     31     register long l = length;
     32     CAST_LONG ti[2];
     33     unsigned char *iv, c, cc;
     34 
     35     iv = ivec;
     36     if (enc) {
     37         while (l--) {
     38             if (n == 0) {
     39                 n2l(iv, v0);
     40                 ti[0] = v0;
     41                 n2l(iv, v1);
     42                 ti[1] = v1;
     43                 CAST_encrypt((CAST_LONG *)ti, schedule);
     44                 iv = ivec;
     45                 t = ti[0];
     46                 l2n(t, iv);
     47                 t = ti[1];
     48                 l2n(t, iv);
     49                 iv = ivec;
     50             }
     51             c = *(in++) ^ iv[n];
     52             *(out++) = c;
     53             iv[n] = c;
     54             n = (n + 1) & 0x07;
     55         }
     56     } else {
     57         while (l--) {
     58             if (n == 0) {
     59                 n2l(iv, v0);
     60                 ti[0] = v0;
     61                 n2l(iv, v1);
     62                 ti[1] = v1;
     63                 CAST_encrypt((CAST_LONG *)ti, schedule);
     64                 iv = ivec;
     65                 t = ti[0];
     66                 l2n(t, iv);
     67                 t = ti[1];
     68                 l2n(t, iv);
     69                 iv = ivec;
     70             }
     71             cc = *(in++);
     72             c = iv[n];
     73             iv[n] = cc;
     74             *(out++) = c ^ cc;
     75             n = (n + 1) & 0x07;
     76         }
     77     }
     78     v0 = v1 = ti[0] = ti[1] = t = c = cc = 0;
     79     *num = n;
     80 }
     81