1/*
2 * Copyright 2011-2016 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 <string.h>
11#include <openssl/crypto.h>
12#include "crypto/modes.h"
13
14int CRYPTO_xts128_encrypt(const XTS128_CONTEXT *ctx,
15 const unsigned char iv[16],
16 const unsigned char *inp, unsigned char *out,
17 size_t len, int enc)
18{
19 const union {
20 long one;
21 char little;
22 } is_endian = {
23 1
24 };
25 union {
26 u64 u[2];
27 u32 d[4];
28 u8 c[16];
29 } tweak, scratch;
30 unsigned int i;
31
32 if (len < 16)
33 return -1;
34
35 memcpy(tweak.c, iv, 16);
36
37 (*ctx->block2) (tweak.c, tweak.c, ctx->key2);
38
39 if (!enc && (len % 16))
40 len -= 16;
41
42 while (len >= 16) {
43#if defined(STRICT_ALIGNMENT)
44 memcpy(scratch.c, inp, 16);
45 scratch.u[0] ^= tweak.u[0];
46 scratch.u[1] ^= tweak.u[1];
47#else
48 scratch.u[0] = ((u64 *)inp)[0] ^ tweak.u[0];
49 scratch.u[1] = ((u64 *)inp)[1] ^ tweak.u[1];
50#endif
51 (*ctx->block1) (scratch.c, scratch.c, ctx->key1);
52#if defined(STRICT_ALIGNMENT)
53 scratch.u[0] ^= tweak.u[0];
54 scratch.u[1] ^= tweak.u[1];
55 memcpy(out, scratch.c, 16);
56#else
57 ((u64 *)out)[0] = scratch.u[0] ^= tweak.u[0];
58 ((u64 *)out)[1] = scratch.u[1] ^= tweak.u[1];
59#endif
60 inp += 16;
61 out += 16;
62 len -= 16;
63
64 if (len == 0)
65 return 0;
66
67 if (is_endian.little) {
68 unsigned int carry, res;
69
70 res = 0x87 & (((int)tweak.d[3]) >> 31);
71 carry = (unsigned int)(tweak.u[0] >> 63);
72 tweak.u[0] = (tweak.u[0] << 1) ^ res;
73 tweak.u[1] = (tweak.u[1] << 1) | carry;
74 } else {
75 size_t c;
76
77 for (c = 0, i = 0; i < 16; ++i) {
78 /*
79 * + substitutes for |, because c is 1 bit
80 */
81 c += ((size_t)tweak.c[i]) << 1;
82 tweak.c[i] = (u8)c;
83 c = c >> 8;
84 }
85 tweak.c[0] ^= (u8)(0x87 & (0 - c));
86 }
87 }
88 if (enc) {
89 for (i = 0; i < len; ++i) {
90 u8 c = inp[i];
91 out[i] = scratch.c[i];
92 scratch.c[i] = c;
93 }
94 scratch.u[0] ^= tweak.u[0];
95 scratch.u[1] ^= tweak.u[1];
96 (*ctx->block1) (scratch.c, scratch.c, ctx->key1);
97 scratch.u[0] ^= tweak.u[0];
98 scratch.u[1] ^= tweak.u[1];
99 memcpy(out - 16, scratch.c, 16);
100 } else {
101 union {
102 u64 u[2];
103 u8 c[16];
104 } tweak1;
105
106 if (is_endian.little) {
107 unsigned int carry, res;
108
109 res = 0x87 & (((int)tweak.d[3]) >> 31);
110 carry = (unsigned int)(tweak.u[0] >> 63);
111 tweak1.u[0] = (tweak.u[0] << 1) ^ res;
112 tweak1.u[1] = (tweak.u[1] << 1) | carry;
113 } else {
114 size_t c;
115
116 for (c = 0, i = 0; i < 16; ++i) {
117 /*
118 * + substitutes for |, because c is 1 bit
119 */
120 c += ((size_t)tweak.c[i]) << 1;
121 tweak1.c[i] = (u8)c;
122 c = c >> 8;
123 }
124 tweak1.c[0] ^= (u8)(0x87 & (0 - c));
125 }
126#if defined(STRICT_ALIGNMENT)
127 memcpy(scratch.c, inp, 16);
128 scratch.u[0] ^= tweak1.u[0];
129 scratch.u[1] ^= tweak1.u[1];
130#else
131 scratch.u[0] = ((u64 *)inp)[0] ^ tweak1.u[0];
132 scratch.u[1] = ((u64 *)inp)[1] ^ tweak1.u[1];
133#endif
134 (*ctx->block1) (scratch.c, scratch.c, ctx->key1);
135 scratch.u[0] ^= tweak1.u[0];
136 scratch.u[1] ^= tweak1.u[1];
137
138 for (i = 0; i < len; ++i) {
139 u8 c = inp[16 + i];
140 out[16 + i] = scratch.c[i];
141 scratch.c[i] = c;
142 }
143 scratch.u[0] ^= tweak.u[0];
144 scratch.u[1] ^= tweak.u[1];
145 (*ctx->block1) (scratch.c, scratch.c, ctx->key1);
146#if defined(STRICT_ALIGNMENT)
147 scratch.u[0] ^= tweak.u[0];
148 scratch.u[1] ^= tweak.u[1];
149 memcpy(out, scratch.c, 16);
150#else
151 ((u64 *)out)[0] = scratch.u[0] ^ tweak.u[0];
152 ((u64 *)out)[1] = scratch.u[1] ^ tweak.u[1];
153#endif
154 }
155
156 return 0;
157}
158