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 are loaded in multiples of 8 bits. What this means is |
14 | * that if you have numbits=12 and length=2 the first 12 bits will be |
15 | * retrieved from the first byte and half the second. The second 12 bits |
16 | * will come from the 3rd and half the 4th byte. |
17 | */ |
18 | void DES_ofb_encrypt(const unsigned char *in, unsigned char *out, int numbits, |
19 | long length, DES_key_schedule *schedule, |
20 | DES_cblock *ivec) |
21 | { |
22 | register DES_LONG d0, d1, vv0, vv1, v0, v1, n = (numbits + 7) / 8; |
23 | register DES_LONG mask0, mask1; |
24 | register long l = length; |
25 | register int num = numbits; |
26 | DES_LONG ti[2]; |
27 | unsigned char *iv; |
28 | |
29 | if (num > 64) |
30 | return; |
31 | if (num > 32) { |
32 | mask0 = 0xffffffffL; |
33 | if (num >= 64) |
34 | mask1 = mask0; |
35 | else |
36 | mask1 = (1L << (num - 32)) - 1; |
37 | } else { |
38 | if (num == 32) |
39 | mask0 = 0xffffffffL; |
40 | else |
41 | mask0 = (1L << num) - 1; |
42 | mask1 = 0x00000000L; |
43 | } |
44 | |
45 | iv = &(*ivec)[0]; |
46 | c2l(iv, v0); |
47 | c2l(iv, v1); |
48 | ti[0] = v0; |
49 | ti[1] = v1; |
50 | while (l-- > 0) { |
51 | ti[0] = v0; |
52 | ti[1] = v1; |
53 | DES_encrypt1((DES_LONG *)ti, schedule, DES_ENCRYPT); |
54 | vv0 = ti[0]; |
55 | vv1 = ti[1]; |
56 | c2ln(in, d0, d1, n); |
57 | in += n; |
58 | d0 = (d0 ^ vv0) & mask0; |
59 | d1 = (d1 ^ vv1) & mask1; |
60 | l2cn(d0, d1, out, n); |
61 | out += n; |
62 | |
63 | if (num == 32) { |
64 | v0 = v1; |
65 | v1 = vv0; |
66 | } else if (num == 64) { |
67 | v0 = vv0; |
68 | v1 = vv1; |
69 | } else if (num > 32) { /* && num != 64 */ |
70 | v0 = ((v1 >> (num - 32)) | (vv0 << (64 - num))) & 0xffffffffL; |
71 | v1 = ((vv0 >> (num - 32)) | (vv1 << (64 - num))) & 0xffffffffL; |
72 | } else { /* num < 32 */ |
73 | |
74 | v0 = ((v0 >> num) | (v1 << (32 - num))) & 0xffffffffL; |
75 | v1 = ((v1 >> num) | (vv0 << (32 - num))) & 0xffffffffL; |
76 | } |
77 | } |
78 | iv = &(*ivec)[0]; |
79 | l2c(v0, iv); |
80 | l2c(v1, iv); |
81 | v0 = v1 = d0 = d1 = ti[0] = ti[1] = vv0 = vv1 = 0; |
82 | } |
83 | |