6859ab65d522e9d93861d1e4c82d34660bca3161
[openssl.git] / crypto / modes / xts128.c
1 /* ====================================================================
2  * Copyright (c) 2011 The OpenSSL Project.  All rights reserved.
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  *
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer. 
10  *
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in
13  *    the documentation and/or other materials provided with the
14  *    distribution.
15  *
16  * 3. All advertising materials mentioning features or use of this
17  *    software must display the following acknowledgment:
18  *    "This product includes software developed by the OpenSSL Project
19  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
20  *
21  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
22  *    endorse or promote products derived from this software without
23  *    prior written permission. For written permission, please contact
24  *    openssl-core@openssl.org.
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26  * 5. Products derived from this software may not be called "OpenSSL"
27  *    nor may "OpenSSL" appear in their names without prior written
28  *    permission of the OpenSSL Project.
29  *
30  * 6. Redistributions of any form whatsoever must retain the following
31  *    acknowledgment:
32  *    "This product includes software developed by the OpenSSL Project
33  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
34  *
35  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
36  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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38  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
39  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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41  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
42  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
43  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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47  * ====================================================================
48  */
49
50 #include <openssl/crypto.h>
51 #include "modes_lcl.h"
52 #include <string.h>
53
54 #ifndef MODES_DEBUG
55 # ifndef NDEBUG
56 #  define NDEBUG
57 # endif
58 #endif
59 #include <assert.h>
60
61 int CRYPTO_xts128_encrypt(const XTS128_CONTEXT *ctx, const unsigned char iv[16],
62         const unsigned char *inp, unsigned char *out,
63         size_t len, int enc)
64 {
65         const union { long one; char little; } is_endian = {1};
66         union { u64 u[2]; u32 d[4]; u8 c[16]; } tweak, scratch;
67         unsigned int i;
68
69         if (len<16) return -1;
70
71         memcpy(tweak.c, iv, 16);
72
73         (*ctx->block2)(tweak.c,tweak.c,ctx->key2);
74
75         if (!enc && (len%16)) len-=16;
76
77         while (len>=16) {
78 #if defined(STRICT_ALIGNMENT)
79                 memcpy(scratch.c,inp,16);
80                 scratch.u[0] ^= tweak.u[0];
81                 scratch.u[1] ^= tweak.u[1];
82 #else
83                 scratch.u[0] = ((u64*)inp)[0]^tweak.u[0];
84                 scratch.u[1] = ((u64*)inp)[1]^tweak.u[1];
85 #endif
86                 (*ctx->block1)(scratch.c,scratch.c,ctx->key1);
87 #if defined(STRICT_ALIGNMENT)
88                 scratch.u[0] ^= tweak.u[0];
89                 scratch.u[1] ^= tweak.u[1];
90                 memcpy(out,scratch.c,16);
91 #else
92                 ((u64*)out)[0] = scratch.u[0]^tweak.u[0];
93                 ((u64*)out)[1] = scratch.u[1]^tweak.u[1];
94 #endif
95                 inp += 16;
96                 out += 16;
97                 len -= 16;
98
99                 if (len==0)     return 0;
100
101                 if (is_endian.little) {
102                         unsigned int carry,res;
103                         
104                         res = 0x87&(((int)tweak.d[3])>>31);
105                         carry = tweak.u[0]>>63;
106                         tweak.u[0] = (tweak.u[0]<<1)^res;
107                         tweak.u[1] = (tweak.u[1]<<1)|carry;
108                 }
109                 else {
110                         unsigned int carry,c;
111
112                         for (carry=0,i=0;i<16;++i) {
113                                 c = tweak.c[i];
114                                 tweak.c[i] = (c<<1)|carry;
115                                 carry = c>>7;
116                         }
117                         tweak.c[0] ^= 0x87&(0-carry);
118                 }
119         }
120         if (enc) {
121                 for (i=0;i<len;++i) {
122                         u8 c = inp[i];
123                         out[i] = scratch.c[i];
124                         scratch.c[i] = c;
125                 }
126                 scratch.u[0] ^= tweak.u[0];
127                 scratch.u[1] ^= tweak.u[1];
128                 (*ctx->block1)(scratch.c,scratch.c,ctx->key1);
129                 scratch.u[0] ^= tweak.u[0];
130                 scratch.u[1] ^= tweak.u[1];
131                 memcpy(out-16,scratch.c,16);
132         }
133         else {
134                 union { u64 u[2]; u8 c[16]; } tweak1;
135
136                 if (is_endian.little) {
137                         unsigned int carry,res;
138
139                         res = 0x87&(((int)tweak.d[3])>>31);
140                         carry = tweak.u[0]>>63;
141                         tweak1.u[0] = (tweak.u[0]<<1)^res;
142                         tweak1.u[1] = (tweak.u[1]<<1)|carry;
143                 }
144                 else {
145                         unsigned int carry,c;
146
147                         for (carry=0,i=0;i<16;++i) {
148                                 c = tweak.c[i];
149                                 tweak1.c[i] = (c<<1)|carry;
150                                 carry = c>>7;
151                         }
152                         tweak1.c[0] ^= 0x87&(0-carry);
153                 }
154 #if defined(STRICT_ALIGNMENT)
155                 memcpy(scratch.c,inp,16);
156                 scratch.u[0] ^= tweak1.u[0];
157                 scratch.u[1] ^= tweak1.u[1];
158 #else
159                 scratch.u[0] = ((u64*)inp)[0]^tweak1.u[0];
160                 scratch.u[1] = ((u64*)inp)[1]^tweak1.u[1];
161 #endif
162                 (*ctx->block1)(scratch.c,scratch.c,ctx->key1);
163                 scratch.u[0] ^= tweak1.u[0];
164                 scratch.u[1] ^= tweak1.u[1];
165
166                 for (i=0;i<len;++i) {
167                         u8 c = inp[16+i];
168                         out[16+i] = scratch.c[i];
169                         scratch.c[i] = c;
170                 }
171                 scratch.u[0] ^= tweak.u[0];
172                 scratch.u[1] ^= tweak.u[1];
173                 (*ctx->block1)(scratch.c,scratch.c,ctx->key1);
174 #if defined(STRICT_ALIGNMENT)
175                 scratch.u[0] ^= tweak.u[0];
176                 scratch.u[1] ^= tweak.u[1];
177                 memcpy (out,scratch.c,16);
178 #else
179                 ((u64*)out)[0] = scratch.u[0]^tweak.u[0];
180                 ((u64*)out)[1] = scratch.u[1]^tweak.u[1];
181 #endif
182         }
183
184         return 0;
185 }