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- /* $OpenBSD: xform.c,v 1.16 2001/08/28 12:20:43 ben Exp $ */
- /*-
- * The authors of this code are John Ioannidis (ji@tla.org),
- * Angelos D. Keromytis (kermit@csd.uch.gr),
- * Niels Provos (provos@physnet.uni-hamburg.de) and
- * Damien Miller (djm@mindrot.org).
- *
- * This code was written by John Ioannidis for BSD/OS in Athens, Greece,
- * in November 1995.
- *
- * Ported to OpenBSD and NetBSD, with additional transforms, in December 1996,
- * by Angelos D. Keromytis.
- *
- * Additional transforms and features in 1997 and 1998 by Angelos D. Keromytis
- * and Niels Provos.
- *
- * Additional features in 1999 by Angelos D. Keromytis.
- *
- * AES XTS implementation in 2008 by Damien Miller
- *
- * Copyright (C) 1995, 1996, 1997, 1998, 1999 by John Ioannidis,
- * Angelos D. Keromytis and Niels Provos.
- *
- * Copyright (C) 2001, Angelos D. Keromytis.
- *
- * Copyright (C) 2008, Damien Miller
- * Copyright (c) 2014 The FreeBSD Foundation
- * All rights reserved.
- *
- * Portions of this software were developed by John-Mark Gurney
- * under sponsorship of the FreeBSD Foundation and
- * Rubicon Communications, LLC (Netgate).
- *
- * Permission to use, copy, and modify this software with or without fee
- * is hereby granted, provided that this entire notice is included in
- * all copies of any software which is or includes a copy or
- * modification of this software.
- * You may use this code under the GNU public license if you so wish. Please
- * contribute changes back to the authors under this freer than GPL license
- * so that we may further the use of strong encryption without limitations to
- * all.
- *
- * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
- * IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
- * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
- * MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
- * PURPOSE.
- */
- #include <sys/cdefs.h>
- __FBSDID("$FreeBSD$");
- #include <sys/types.h>
- #include <opencrypto/xform_enc.h>
- static int aes_xts_setkey(void *, const uint8_t *, int);
- static void aes_xts_encrypt(void *, const uint8_t *, uint8_t *);
- static void aes_xts_decrypt(void *, const uint8_t *, uint8_t *);
- static void aes_xts_reinit(void *, const uint8_t *);
- /* Encryption instances */
- struct enc_xform enc_xform_aes_xts = {
- .type = CRYPTO_AES_XTS,
- .name = "AES-XTS",
- .ctxsize = sizeof(struct aes_xts_ctx),
- .blocksize = AES_BLOCK_LEN,
- .ivsize = AES_XTS_IV_LEN,
- .minkey = AES_XTS_MIN_KEY,
- .maxkey = AES_XTS_MAX_KEY,
- .encrypt = aes_xts_encrypt,
- .decrypt = aes_xts_decrypt,
- .setkey = aes_xts_setkey,
- .reinit = aes_xts_reinit
- };
- /*
- * Encryption wrapper routines.
- */
- static void
- aes_xts_reinit(void *key, const uint8_t *iv)
- {
- struct aes_xts_ctx *ctx = key;
- uint64_t blocknum;
- u_int i;
- /*
- * Prepare tweak as E_k2(IV). IV is specified as LE representation
- * of a 64-bit block number which we allow to be passed in directly.
- */
- bcopy(iv, &blocknum, AES_XTS_IVSIZE);
- for (i = 0; i < AES_XTS_IVSIZE; i++) {
- ctx->tweak[i] = blocknum & 0xff;
- blocknum >>= 8;
- }
- /* Last 64 bits of IV are always zero */
- bzero(ctx->tweak + AES_XTS_IVSIZE, AES_XTS_IVSIZE);
- rijndael_encrypt(&ctx->key2, ctx->tweak, ctx->tweak);
- }
- static void
- aes_xts_crypt(struct aes_xts_ctx *ctx, const uint8_t *in, uint8_t *out,
- u_int do_encrypt)
- {
- uint8_t block[AES_XTS_BLOCKSIZE];
- u_int i, carry_in, carry_out;
- for (i = 0; i < AES_XTS_BLOCKSIZE; i++)
- block[i] = in[i] ^ ctx->tweak[i];
- if (do_encrypt)
- rijndael_encrypt(&ctx->key1, block, out);
- else
- rijndael_decrypt(&ctx->key1, block, out);
- for (i = 0; i < AES_XTS_BLOCKSIZE; i++)
- out[i] ^= ctx->tweak[i];
- /* Exponentiate tweak */
- carry_in = 0;
- for (i = 0; i < AES_XTS_BLOCKSIZE; i++) {
- carry_out = ctx->tweak[i] & 0x80;
- ctx->tweak[i] = (ctx->tweak[i] << 1) | (carry_in ? 1 : 0);
- carry_in = carry_out;
- }
- if (carry_in)
- ctx->tweak[0] ^= AES_XTS_ALPHA;
- explicit_bzero(block, sizeof(block));
- }
- static void
- aes_xts_encrypt(void *key, const uint8_t *in, uint8_t *out)
- {
- aes_xts_crypt(key, in, out, 1);
- }
- static void
- aes_xts_decrypt(void *key, const uint8_t *in, uint8_t *out)
- {
- aes_xts_crypt(key, in, out, 0);
- }
- static int
- aes_xts_setkey(void *sched, const uint8_t *key, int len)
- {
- struct aes_xts_ctx *ctx;
- if (len != 32 && len != 64)
- return (EINVAL);
- ctx = sched;
- rijndael_set_key(&ctx->key1, key, len * 4);
- rijndael_set_key(&ctx->key2, key + (len / 2), len * 4);
- return (0);
- }
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