1 /*
2 * Copyright 2011-2020 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the OpenSSL license (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 <openssl/crypto.h>
11 #include "modes_local.h"
12 #include <string.h>
13
14 #ifndef STRICT_ALIGNMENT
15 # ifdef __GNUC__
16 typedef u64 u64_a1 __attribute((__aligned__(1)));
17 # else
18 typedef u64 u64_a1;
19 # endif
20 #endif
21
CRYPTO_xts128_encrypt(const XTS128_CONTEXT * ctx,const unsigned char iv[16],const unsigned char * inp,unsigned char * out,size_t len,int enc)22 int CRYPTO_xts128_encrypt(const XTS128_CONTEXT *ctx,
23 const unsigned char iv[16],
24 const unsigned char *inp, unsigned char *out,
25 size_t len, int enc)
26 {
27 const union {
28 long one;
29 char little;
30 } is_endian = {
31 1
32 };
33 union {
34 u64 u[2];
35 u32 d[4];
36 u8 c[16];
37 } tweak, scratch;
38 unsigned int i;
39
40 if (len < 16)
41 return -1;
42
43 memcpy(tweak.c, iv, 16);
44
45 (*ctx->block2) (tweak.c, tweak.c, ctx->key2);
46
47 if (!enc && (len % 16))
48 len -= 16;
49
50 while (len >= 16) {
51 #if defined(STRICT_ALIGNMENT)
52 memcpy(scratch.c, inp, 16);
53 scratch.u[0] ^= tweak.u[0];
54 scratch.u[1] ^= tweak.u[1];
55 #else
56 scratch.u[0] = ((u64_a1 *)inp)[0] ^ tweak.u[0];
57 scratch.u[1] = ((u64_a1 *)inp)[1] ^ tweak.u[1];
58 #endif
59 (*ctx->block1) (scratch.c, scratch.c, ctx->key1);
60 #if defined(STRICT_ALIGNMENT)
61 scratch.u[0] ^= tweak.u[0];
62 scratch.u[1] ^= tweak.u[1];
63 memcpy(out, scratch.c, 16);
64 #else
65 ((u64_a1 *)out)[0] = scratch.u[0] ^= tweak.u[0];
66 ((u64_a1 *)out)[1] = scratch.u[1] ^= tweak.u[1];
67 #endif
68 inp += 16;
69 out += 16;
70 len -= 16;
71
72 if (len == 0)
73 return 0;
74
75 if (is_endian.little) {
76 unsigned int carry, res;
77
78 res = 0x87 & (((int)tweak.d[3]) >> 31);
79 carry = (unsigned int)(tweak.u[0] >> 63);
80 tweak.u[0] = (tweak.u[0] << 1) ^ res;
81 tweak.u[1] = (tweak.u[1] << 1) | carry;
82 } else {
83 size_t c;
84
85 for (c = 0, i = 0; i < 16; ++i) {
86 /*
87 * + substitutes for |, because c is 1 bit
88 */
89 c += ((size_t)tweak.c[i]) << 1;
90 tweak.c[i] = (u8)c;
91 c = c >> 8;
92 }
93 tweak.c[0] ^= (u8)(0x87 & (0 - c));
94 }
95 }
96 if (enc) {
97 for (i = 0; i < len; ++i) {
98 u8 c = inp[i];
99 out[i] = scratch.c[i];
100 scratch.c[i] = c;
101 }
102 scratch.u[0] ^= tweak.u[0];
103 scratch.u[1] ^= tweak.u[1];
104 (*ctx->block1) (scratch.c, scratch.c, ctx->key1);
105 scratch.u[0] ^= tweak.u[0];
106 scratch.u[1] ^= tweak.u[1];
107 memcpy(out - 16, scratch.c, 16);
108 } else {
109 union {
110 u64 u[2];
111 u8 c[16];
112 } tweak1;
113
114 if (is_endian.little) {
115 unsigned int carry, res;
116
117 res = 0x87 & (((int)tweak.d[3]) >> 31);
118 carry = (unsigned int)(tweak.u[0] >> 63);
119 tweak1.u[0] = (tweak.u[0] << 1) ^ res;
120 tweak1.u[1] = (tweak.u[1] << 1) | carry;
121 } else {
122 size_t c;
123
124 for (c = 0, i = 0; i < 16; ++i) {
125 /*
126 * + substitutes for |, because c is 1 bit
127 */
128 c += ((size_t)tweak.c[i]) << 1;
129 tweak1.c[i] = (u8)c;
130 c = c >> 8;
131 }
132 tweak1.c[0] ^= (u8)(0x87 & (0 - c));
133 }
134 #if defined(STRICT_ALIGNMENT)
135 memcpy(scratch.c, inp, 16);
136 scratch.u[0] ^= tweak1.u[0];
137 scratch.u[1] ^= tweak1.u[1];
138 #else
139 scratch.u[0] = ((u64_a1 *)inp)[0] ^ tweak1.u[0];
140 scratch.u[1] = ((u64_a1 *)inp)[1] ^ tweak1.u[1];
141 #endif
142 (*ctx->block1) (scratch.c, scratch.c, ctx->key1);
143 scratch.u[0] ^= tweak1.u[0];
144 scratch.u[1] ^= tweak1.u[1];
145
146 for (i = 0; i < len; ++i) {
147 u8 c = inp[16 + i];
148 out[16 + i] = scratch.c[i];
149 scratch.c[i] = c;
150 }
151 scratch.u[0] ^= tweak.u[0];
152 scratch.u[1] ^= tweak.u[1];
153 (*ctx->block1) (scratch.c, scratch.c, ctx->key1);
154 #if defined(STRICT_ALIGNMENT)
155 scratch.u[0] ^= tweak.u[0];
156 scratch.u[1] ^= tweak.u[1];
157 memcpy(out, scratch.c, 16);
158 #else
159 ((u64_a1 *)out)[0] = scratch.u[0] ^ tweak.u[0];
160 ((u64_a1 *)out)[1] = scratch.u[1] ^ tweak.u[1];
161 #endif
162 }
163
164 return 0;
165 }
166