xform_aes_cbc.c

/*	$OpenBSD: xform.c,v 1.16 2001/08/28 12:20:43 ben Exp $	*/
/*-
 * The authors of this code are John Ioannidis ([email protected]),
 * Angelos D. Keromytis ([email protected]),
 * Niels Provos ([email protected]) and
 * Damien Miller ([email protected]).
 *
 * 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/types.h>
#include <crypto/rijndael/rijndael.h>
#include <opencrypto/xform_enc.h>

struct aes_cbc_ctx {
	rijndael_ctx key;
	char iv[AES_BLOCK_LEN];
};

static	int aes_cbc_setkey(void *, const uint8_t *, int);
static	void aes_cbc_encrypt(void *, const uint8_t *, uint8_t *);
static	void aes_cbc_decrypt(void *, const uint8_t *, uint8_t *);
static	void aes_cbc_encrypt_multi(void *, const uint8_t *, uint8_t *, size_t);
static	void aes_cbc_decrypt_multi(void *, const uint8_t *, uint8_t *, size_t);
static  void aes_cbc_reinit(void *, const uint8_t *, size_t);

/* Encryption instances */
const struct enc_xform enc_xform_aes_cbc = {
	.type = CRYPTO_AES_CBC,
	.name = "AES-CBC",
	.ctxsize = sizeof(struct aes_cbc_ctx),
	.blocksize = AES_BLOCK_LEN,
	.ivsize = AES_BLOCK_LEN,
	.minkey = AES_MIN_KEY,
	.maxkey = AES_MAX_KEY,
	.setkey = aes_cbc_setkey,
	.reinit = aes_cbc_reinit,
	.encrypt = aes_cbc_encrypt,
	.decrypt = aes_cbc_decrypt,
	.encrypt_multi = aes_cbc_encrypt_multi,
	.decrypt_multi = aes_cbc_decrypt_multi,
};

/*
 * Encryption wrapper routines.
 */
static void
aes_cbc_encrypt(void *vctx, const uint8_t *in, uint8_t *out)
{
	struct aes_cbc_ctx *ctx = vctx;

	for (u_int i = 0; i < AES_BLOCK_LEN; i++)
		out[i] = in[i] ^ ctx->iv[i];
	rijndael_encrypt(&ctx->key, out, out);
	memcpy(ctx->iv, out, AES_BLOCK_LEN);
}

static void
aes_cbc_decrypt(void *vctx, const uint8_t *in, uint8_t *out)
{
	struct aes_cbc_ctx *ctx = vctx;
	char block[AES_BLOCK_LEN];

	memcpy(block, in, AES_BLOCK_LEN);
	rijndael_decrypt(&ctx->key, in, out);
	for (u_int i = 0; i < AES_BLOCK_LEN; i++)
		out[i] ^= ctx->iv[i];
	memcpy(ctx->iv, block, AES_BLOCK_LEN);
	explicit_bzero(block, sizeof(block));
}

static void
aes_cbc_encrypt_multi(void *vctx, const uint8_t *in, uint8_t *out, size_t len)
{
	struct aes_cbc_ctx *ctx = vctx;

	KASSERT(len % AES_BLOCK_LEN == 0, ("%s: invalid length", __func__));
	while (len > 0) {
		for (u_int i = 0; i < AES_BLOCK_LEN; i++)
			out[i] = in[i] ^ ctx->iv[i];
		rijndael_encrypt(&ctx->key, out, out);
		memcpy(ctx->iv, out, AES_BLOCK_LEN);
		out += AES_BLOCK_LEN;
		in += AES_BLOCK_LEN;
		len -= AES_BLOCK_LEN;
	}
}

static void
aes_cbc_decrypt_multi(void *vctx, const uint8_t *in, uint8_t *out, size_t len)
{
	struct aes_cbc_ctx *ctx = vctx;
	char block[AES_BLOCK_LEN];

	KASSERT(len % AES_BLOCK_LEN == 0, ("%s: invalid length", __func__));
	while (len > 0) {
		memcpy(block, in, AES_BLOCK_LEN);
		rijndael_decrypt(&ctx->key, in, out);
		for (u_int i = 0; i < AES_BLOCK_LEN; i++)
			out[i] ^= ctx->iv[i];
		memcpy(ctx->iv, block, AES_BLOCK_LEN);
		out += AES_BLOCK_LEN;
		in += AES_BLOCK_LEN;
		len -= AES_BLOCK_LEN;
	}
	explicit_bzero(block, sizeof(block));
}

static int
aes_cbc_setkey(void *vctx, const uint8_t *key, int len)
{
	struct aes_cbc_ctx *ctx = vctx;

	if (len != 16 && len != 24 && len != 32)
		return (EINVAL);

	rijndael_set_key(&ctx->key, key, len * 8);
	return (0);
}

static void
aes_cbc_reinit(void *vctx, const uint8_t *iv, size_t iv_len)
{
	struct aes_cbc_ctx *ctx = vctx;

	KASSERT(iv_len == sizeof(ctx->iv), ("%s: bad IV length", __func__));
	memcpy(ctx->iv, iv, sizeof(ctx->iv));
}