165 lines
4.5 KiB
C
165 lines
4.5 KiB
C
/* $OpenBSD: xform.c,v 1.16 2001/08/28 12:20:43 ben Exp $ */
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/*-
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* The authors of this code are John Ioannidis (ji@tla.org),
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* Angelos D. Keromytis (kermit@csd.uch.gr),
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* Niels Provos (provos@physnet.uni-hamburg.de) and
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* Damien Miller (djm@mindrot.org).
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*
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* This code was written by John Ioannidis for BSD/OS in Athens, Greece,
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* in November 1995.
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*
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* Ported to OpenBSD and NetBSD, with additional transforms, in December 1996,
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* by Angelos D. Keromytis.
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*
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* Additional transforms and features in 1997 and 1998 by Angelos D. Keromytis
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* and Niels Provos.
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*
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* Additional features in 1999 by Angelos D. Keromytis.
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*
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* AES XTS implementation in 2008 by Damien Miller
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*
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* Copyright (C) 1995, 1996, 1997, 1998, 1999 by John Ioannidis,
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* Angelos D. Keromytis and Niels Provos.
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*
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* Copyright (C) 2001, Angelos D. Keromytis.
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*
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* Copyright (C) 2008, Damien Miller
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* Copyright (c) 2014 The FreeBSD Foundation
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* All rights reserved.
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*
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* Portions of this software were developed by John-Mark Gurney
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* under sponsorship of the FreeBSD Foundation and
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* Rubicon Communications, LLC (Netgate).
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*
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* Permission to use, copy, and modify this software with or without fee
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* is hereby granted, provided that this entire notice is included in
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* all copies of any software which is or includes a copy or
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* modification of this software.
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* You may use this code under the GNU public license if you so wish. Please
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* contribute changes back to the authors under this freer than GPL license
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* so that we may further the use of strong encryption without limitations to
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* all.
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*
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* THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
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* IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
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* REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
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* MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
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* PURPOSE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <opencrypto/xform_enc.h>
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static int aes_xts_setkey(u_int8_t **, u_int8_t *, int);
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static void aes_xts_encrypt(caddr_t, u_int8_t *);
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static void aes_xts_decrypt(caddr_t, u_int8_t *);
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static void aes_xts_zerokey(u_int8_t **);
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static void aes_xts_reinit(caddr_t, u_int8_t *);
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/* Encryption instances */
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struct enc_xform enc_xform_aes_xts = {
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CRYPTO_AES_XTS, "AES-XTS",
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AES_BLOCK_LEN, AES_XTS_IV_LEN, AES_XTS_MIN_KEY, AES_XTS_MAX_KEY,
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aes_xts_encrypt,
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aes_xts_decrypt,
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aes_xts_setkey,
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aes_xts_zerokey,
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aes_xts_reinit
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};
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/*
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* Encryption wrapper routines.
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*/
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static void
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aes_xts_reinit(caddr_t key, u_int8_t *iv)
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{
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struct aes_xts_ctx *ctx = (struct aes_xts_ctx *)key;
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u_int64_t blocknum;
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u_int i;
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/*
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* Prepare tweak as E_k2(IV). IV is specified as LE representation
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* of a 64-bit block number which we allow to be passed in directly.
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*/
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bcopy(iv, &blocknum, AES_XTS_IVSIZE);
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for (i = 0; i < AES_XTS_IVSIZE; i++) {
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ctx->tweak[i] = blocknum & 0xff;
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blocknum >>= 8;
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}
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/* Last 64 bits of IV are always zero */
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bzero(ctx->tweak + AES_XTS_IVSIZE, AES_XTS_IVSIZE);
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rijndael_encrypt(&ctx->key2, ctx->tweak, ctx->tweak);
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}
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static void
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aes_xts_crypt(struct aes_xts_ctx *ctx, u_int8_t *data, u_int do_encrypt)
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{
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u_int8_t block[AES_XTS_BLOCKSIZE];
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u_int i, carry_in, carry_out;
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for (i = 0; i < AES_XTS_BLOCKSIZE; i++)
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block[i] = data[i] ^ ctx->tweak[i];
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if (do_encrypt)
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rijndael_encrypt(&ctx->key1, block, data);
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else
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rijndael_decrypt(&ctx->key1, block, data);
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for (i = 0; i < AES_XTS_BLOCKSIZE; i++)
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data[i] ^= ctx->tweak[i];
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/* Exponentiate tweak */
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carry_in = 0;
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for (i = 0; i < AES_XTS_BLOCKSIZE; i++) {
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carry_out = ctx->tweak[i] & 0x80;
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ctx->tweak[i] = (ctx->tweak[i] << 1) | (carry_in ? 1 : 0);
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carry_in = carry_out;
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}
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if (carry_in)
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ctx->tweak[0] ^= AES_XTS_ALPHA;
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bzero(block, sizeof(block));
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}
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static void
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aes_xts_encrypt(caddr_t key, u_int8_t *data)
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{
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aes_xts_crypt((struct aes_xts_ctx *)key, data, 1);
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}
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static void
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aes_xts_decrypt(caddr_t key, u_int8_t *data)
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{
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aes_xts_crypt((struct aes_xts_ctx *)key, data, 0);
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}
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static int
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aes_xts_setkey(u_int8_t **sched, u_int8_t *key, int len)
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{
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struct aes_xts_ctx *ctx;
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if (len != 32 && len != 64)
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return EINVAL;
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*sched = KMALLOC(sizeof(struct aes_xts_ctx), M_CRYPTO_DATA,
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M_NOWAIT | M_ZERO);
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if (*sched == NULL)
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return ENOMEM;
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ctx = (struct aes_xts_ctx *)*sched;
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rijndael_set_key(&ctx->key1, key, len * 4);
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rijndael_set_key(&ctx->key2, key + (len / 2), len * 4);
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return 0;
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}
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static void
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aes_xts_zerokey(u_int8_t **sched)
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{
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bzero(*sched, sizeof(struct aes_xts_ctx));
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KFREE(*sched, M_CRYPTO_DATA);
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*sched = NULL;
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}
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