1 /* $OpenBSD: xform.c,v 1.16 2001/08/28 12:20:43 ben Exp $ */
2 /*-
3 * The authors of this code are John Ioannidis (ji@tla.org),
4 * Angelos D. Keromytis (kermit@csd.uch.gr),
5 * Niels Provos (provos@physnet.uni-hamburg.de) and
6 * Damien Miller (djm@mindrot.org).
7 *
8 * This code was written by John Ioannidis for BSD/OS in Athens, Greece,
9 * in November 1995.
10 *
11 * Ported to OpenBSD and NetBSD, with additional transforms, in December 1996,
12 * by Angelos D. Keromytis.
13 *
14 * Additional transforms and features in 1997 and 1998 by Angelos D. Keromytis
15 * and Niels Provos.
16 *
17 * Additional features in 1999 by Angelos D. Keromytis.
18 *
19 * AES XTS implementation in 2008 by Damien Miller
20 *
21 * Copyright (C) 1995, 1996, 1997, 1998, 1999 by John Ioannidis,
22 * Angelos D. Keromytis and Niels Provos.
23 *
24 * Copyright (C) 2001, Angelos D. Keromytis.
25 *
26 * Copyright (C) 2008, Damien Miller
27 * Copyright (c) 2014 The FreeBSD Foundation
28 * All rights reserved.
29 *
30 * Portions of this software were developed by John-Mark Gurney
31 * under sponsorship of the FreeBSD Foundation and
32 * Rubicon Communications, LLC (Netgate).
33 *
34 * Permission to use, copy, and modify this software with or without fee
35 * is hereby granted, provided that this entire notice is included in
36 * all copies of any software which is or includes a copy or
37 * modification of this software.
38 * You may use this code under the GNU public license if you so wish. Please
39 * contribute changes back to the authors under this freer than GPL license
40 * so that we may further the use of strong encryption without limitations to
41 * all.
42 *
43 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
44 * IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
45 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
46 * MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
47 * PURPOSE.
48 */
49
50 #include <sys/cdefs.h>
51 __FBSDID("$FreeBSD$");
52
53 #include <sys/types.h>
54 #include <sys/systm.h>
55 #include <opencrypto/xform_enc.h>
56
57 static int aes_xts_setkey(void *, const uint8_t *, int);
58 static void aes_xts_encrypt(void *, const uint8_t *, uint8_t *);
59 static void aes_xts_decrypt(void *, const uint8_t *, uint8_t *);
60 static void aes_xts_encrypt_multi(void *, const uint8_t *, uint8_t *, size_t);
61 static void aes_xts_decrypt_multi(void *, const uint8_t *, uint8_t *, size_t);
62 static void aes_xts_reinit(void *, const uint8_t *, size_t);
63
64 /* Encryption instances */
65 const struct enc_xform enc_xform_aes_xts = {
66 .type = CRYPTO_AES_XTS,
67 .name = "AES-XTS",
68 .ctxsize = sizeof(struct aes_xts_ctx),
69 .blocksize = AES_BLOCK_LEN,
70 .ivsize = AES_XTS_IV_LEN,
71 .minkey = AES_XTS_MIN_KEY,
72 .maxkey = AES_XTS_MAX_KEY,
73 .setkey = aes_xts_setkey,
74 .reinit = aes_xts_reinit,
75 .encrypt = aes_xts_encrypt,
76 .decrypt = aes_xts_decrypt,
77 .encrypt_multi = aes_xts_encrypt_multi,
78 .decrypt_multi = aes_xts_decrypt_multi,
79 };
80
81 /*
82 * Encryption wrapper routines.
83 */
84 static void
85 aes_xts_reinit(void *key, const uint8_t *iv, size_t ivlen)
86 {
87 struct aes_xts_ctx *ctx = key;
88 uint64_t blocknum;
89 u_int i;
90
91 KASSERT(ivlen == sizeof(blocknum),
92 ("%s: invalid IV length", __func__));
93
94 /*
95 * Prepare tweak as E_k2(IV). IV is specified as LE representation
96 * of a 64-bit block number which we allow to be passed in directly.
97 */
98 bcopy(iv, &blocknum, AES_XTS_IVSIZE);
99 for (i = 0; i < AES_XTS_IVSIZE; i++) {
100 ctx->tweak[i] = blocknum & 0xff;
101 blocknum >>= 8;
102 }
103 /* Last 64 bits of IV are always zero */
104 bzero(ctx->tweak + AES_XTS_IVSIZE, AES_XTS_IVSIZE);
105
106 rijndael_encrypt(&ctx->key2, ctx->tweak, ctx->tweak);
107 }
108
109 static void
110 aes_xts_crypt(struct aes_xts_ctx *ctx, const uint8_t *in, uint8_t *out,
111 size_t len, bool do_encrypt)
112 {
113 uint8_t block[AES_XTS_BLOCKSIZE];
114 u_int i, carry_in, carry_out;
115
116 KASSERT(len % AES_XTS_BLOCKSIZE == 0, ("%s: invalid length", __func__));
117 while (len > 0) {
118 for (i = 0; i < AES_XTS_BLOCKSIZE; i++)
119 block[i] = in[i] ^ ctx->tweak[i];
120
121 if (do_encrypt)
122 rijndael_encrypt(&ctx->key1, block, out);
123 else
124 rijndael_decrypt(&ctx->key1, block, out);
125
126 for (i = 0; i < AES_XTS_BLOCKSIZE; i++)
127 out[i] ^= ctx->tweak[i];
128
129 /* Exponentiate tweak */
130 carry_in = 0;
131 for (i = 0; i < AES_XTS_BLOCKSIZE; i++) {
132 carry_out = ctx->tweak[i] & 0x80;
133 ctx->tweak[i] = (ctx->tweak[i] << 1) | (carry_in ? 1 : 0);
134 carry_in = carry_out;
135 }
136 if (carry_in)
137 ctx->tweak[0] ^= AES_XTS_ALPHA;
138
139 in += AES_XTS_BLOCKSIZE;
140 out += AES_XTS_BLOCKSIZE;
141 len -= AES_XTS_BLOCKSIZE;
142 }
143 explicit_bzero(block, sizeof(block));
144 }
145
146 static void
147 aes_xts_encrypt(void *key, const uint8_t *in, uint8_t *out)
148 {
149 aes_xts_crypt(key, in, out, AES_XTS_BLOCKSIZE, true);
150 }
151
152 static void
153 aes_xts_decrypt(void *key, const uint8_t *in, uint8_t *out)
154 {
155 aes_xts_crypt(key, in, out, AES_XTS_BLOCKSIZE, false);
156 }
157
158 static void
159 aes_xts_encrypt_multi(void *vctx, const uint8_t *in, uint8_t *out, size_t len)
160 {
161 aes_xts_crypt(vctx, in, out, len, true);
162 }
163
164 static void
165 aes_xts_decrypt_multi(void *vctx, const uint8_t *in, uint8_t *out, size_t len)
166 {
167 aes_xts_crypt(vctx, in, out, len, false);
168 }
169
170 static int
171 aes_xts_setkey(void *sched, const uint8_t *key, int len)
172 {
173 struct aes_xts_ctx *ctx;
174
175 if (len != 32 && len != 64)
176 return (EINVAL);
177
178 ctx = sched;
179
180 rijndael_set_key(&ctx->key1, key, len * 4);
181 rijndael_set_key(&ctx->key2, key + (len / 2), len * 4);
182
183 return (0);
184 }
Cache object: 96b9cd234dac3c723d633ac607c43d3b
|