1 /*
2 * Copyright 2008-2021 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 <string.h>
11 #include <openssl/crypto.h>
12 #include "crypto/modes.h"
13
14 #if defined(__GNUC__) && !defined(STRICT_ALIGNMENT)
15 typedef size_t size_t_aX __attribute((__aligned__(1)));
16 #else
17 typedef size_t size_t_aX;
18 #endif
19
20 /*
21 * The input and output encrypted as though 128bit ofb mode is being used.
22 * The extra state information to record how much of the 128bit block we have
23 * used is contained in *num;
24 */
CRYPTO_ofb128_encrypt(const unsigned char * in,unsigned char * out,size_t len,const void * key,unsigned char ivec[16],int * num,block128_f block)25 void CRYPTO_ofb128_encrypt(const unsigned char *in, unsigned char *out,
26 size_t len, const void *key,
27 unsigned char ivec[16], int *num, block128_f block)
28 {
29 unsigned int n;
30 size_t l = 0;
31
32 if (*num < 0) {
33 /* There is no good way to signal an error return from here */
34 *num = -1;
35 return;
36 }
37 n = *num;
38
39 #if !defined(OPENSSL_SMALL_FOOTPRINT)
40 if (16 % sizeof(size_t) == 0) { /* always true actually */
41 do {
42 while (n && len) {
43 *(out++) = *(in++) ^ ivec[n];
44 --len;
45 n = (n + 1) % 16;
46 }
47 # if defined(STRICT_ALIGNMENT)
48 if (((size_t)in | (size_t)out | (size_t)ivec) % sizeof(size_t) !=
49 0)
50 break;
51 # endif
52 while (len >= 16) {
53 (*block) (ivec, ivec, key);
54 for (; n < 16; n += sizeof(size_t))
55 *(size_t_aX *)(out + n) =
56 *(size_t_aX *)(in + n)
57 ^ *(size_t_aX *)(ivec + n);
58 len -= 16;
59 out += 16;
60 in += 16;
61 n = 0;
62 }
63 if (len) {
64 (*block) (ivec, ivec, key);
65 while (len--) {
66 out[n] = in[n] ^ ivec[n];
67 ++n;
68 }
69 }
70 *num = n;
71 return;
72 } while (0);
73 }
74 /* the rest would be commonly eliminated by x86* compiler */
75 #endif
76 while (l < len) {
77 if (n == 0) {
78 (*block) (ivec, ivec, key);
79 }
80 out[l] = in[l] ^ ivec[n];
81 ++l;
82 n = (n + 1) % 16;
83 }
84
85 *num = n;
86 }
87