xref: /openssl/crypto/cast/c_ofb64.c (revision 33388b44)
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 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  */
CAST_ofb64_encrypt(const unsigned char * in,unsigned char * out,long length,const CAST_KEY * schedule,unsigned char * ivec,int * num)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 }
68