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#include "des_local.h"
11
12/*
13 * The input and output encrypted as though 64bit cfb mode is being used.
14 * The extra state information to record how much of the 64bit block we have
15 * used is contained in *num;
16 */
17
18void DES_cfb64_encrypt(const unsigned char *in, unsigned char *out,
19 long length, DES_key_schedule *schedule,
20 DES_cblock *ivec, int *num, int enc)
21{
22 register DES_LONG v0, v1;
23 register long l = length;
24 register int n = *num;
25 DES_LONG ti[2];
26 unsigned char *iv, c, cc;
27
28 iv = &(*ivec)[0];
29 if (enc) {
30 while (l--) {
31 if (n == 0) {
32 c2l(iv, v0);
33 ti[0] = v0;
34 c2l(iv, v1);
35 ti[1] = v1;
36 DES_encrypt1(ti, schedule, DES_ENCRYPT);
37 iv = &(*ivec)[0];
38 v0 = ti[0];
39 l2c(v0, iv);
40 v0 = ti[1];
41 l2c(v0, iv);
42 iv = &(*ivec)[0];
43 }
44 c = *(in++) ^ iv[n];
45 *(out++) = c;
46 iv[n] = c;
47 n = (n + 1) & 0x07;
48 }
49 } else {
50 while (l--) {
51 if (n == 0) {
52 c2l(iv, v0);
53 ti[0] = v0;
54 c2l(iv, v1);
55 ti[1] = v1;
56 DES_encrypt1(ti, schedule, DES_ENCRYPT);
57 iv = &(*ivec)[0];
58 v0 = ti[0];
59 l2c(v0, iv);
60 v0 = ti[1];
61 l2c(v0, iv);
62 iv = &(*ivec)[0];
63 }
64 cc = *(in++);
65 c = iv[n];
66 iv[n] = cc;
67 *(out++) = c ^ cc;
68 n = (n + 1) & 0x07;
69 }
70 }
71 v0 = v1 = ti[0] = ti[1] = c = cc = 0;
72 *num = n;
73}
74