freebsd-dev/sys/opencrypto/xform_aes_xts.c
John Baldwin 3e9470482a Various cleanups to the software encryption transform interface.
- Consistently use 'void *' for key schedules / key contexts instead
  of a mix of 'caddr_t', 'uint8_t *', and 'void *'.

- Add a ctxsize member to enc_xform similar to what auth transforms use
  and require callers to malloc/zfree the context.  The setkey callback
  now supplies the caller-allocated context pointer and the zerokey
  callback is removed.  Callers now always use zfree() to ensure
  key contexts are zeroed.

- Consistently use C99 initializers for all statically-initialized
  instances of 'struct enc_xform'.

- Change the encrypt and decrypt functions to accept separate in and
  out buffer pointers.  Almost all of the backend crypto functions
  already supported separate input and output buffers and this makes
  it simpler to support separate buffers in OCF.

- Remove xform_userland.h shim to permit transforms to be compiled in
  userland.  Transforms no longer call malloc/free directly.

Reviewed by:	cem (earlier version)
Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D24855
2020-05-20 21:21:01 +00:00

157 lines
4.3 KiB
C

/* $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 <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);
}