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
25void 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