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 * DES low level APIs are deprecated for public use, but still ok for internal
12 * use.
13 */
14#include "internal/deprecated.h"
15
16#include "des_local.h"
17
18/*
19 * The input and output encrypted as though 64bit cfb mode is being used.
20 * The extra state information to record how much of the 64bit block we have
21 * used is contained in *num;
22 */
23
24void DES_cfb64_encrypt(const unsigned char *in, unsigned char *out,
25                       long length, DES_key_schedule *schedule,
26                       DES_cblock *ivec, int *num, int enc)
27{
28    register DES_LONG v0, v1;
29    register long l = length;
30    register int n = *num;
31    DES_LONG ti[2];
32    unsigned char *iv, c, cc;
33
34    iv = &(*ivec)[0];
35    if (enc) {
36        while (l--) {
37            if (n == 0) {
38                c2l(iv, v0);
39                ti[0] = v0;
40                c2l(iv, v1);
41                ti[1] = v1;
42                DES_encrypt1(ti, schedule, DES_ENCRYPT);
43                iv = &(*ivec)[0];
44                v0 = ti[0];
45                l2c(v0, iv);
46                v0 = ti[1];
47                l2c(v0, iv);
48                iv = &(*ivec)[0];
49            }
50            c = *(in++) ^ iv[n];
51            *(out++) = c;
52            iv[n] = c;
53            n = (n + 1) & 0x07;
54        }
55    } else {
56        while (l--) {
57            if (n == 0) {
58                c2l(iv, v0);
59                ti[0] = v0;
60                c2l(iv, v1);
61                ti[1] = v1;
62                DES_encrypt1(ti, schedule, DES_ENCRYPT);
63                iv = &(*ivec)[0];
64                v0 = ti[0];
65                l2c(v0, iv);
66                v0 = ti[1];
67                l2c(v0, iv);
68                iv = &(*ivec)[0];
69            }
70            cc = *(in++);
71            c = iv[n];
72            iv[n] = cc;
73            *(out++) = c ^ cc;
74            n = (n + 1) & 0x07;
75        }
76    }
77    v0 = v1 = ti[0] = ti[1] = c = cc = 0;
78    *num = n;
79}
80