xts128.c: initial draft.

/* ====================================================================

 * Copyright (c) 2011 The OpenSSL Project.  All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer. 

 *

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in

 *    the documentation and/or other materials provided with the

 *    distribution.

 *

 * 3. All advertising materials mentioning features or use of this

 *    software must display the following acknowledgment:

 *    "This product includes software developed by the OpenSSL Project

 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"

 *

 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to

 *    endorse or promote products derived from this software without

 *    prior written permission. For written permission, please contact

 *    openssl-core@openssl.org.

 *

 * 5. Products derived from this software may not be called "OpenSSL"

 *    nor may "OpenSSL" appear in their names without prior written

 *    permission of the OpenSSL Project.

 *

 * 6. Redistributions of any form whatsoever must retain the following

 *    acknowledgment:

 *    "This product includes software developed by the OpenSSL Project

 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"

 *

 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY

 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR

 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED

 * OF THE POSSIBILITY OF SUCH DAMAGE.

 * ====================================================================

 */

#include <openssl/crypto.h>

#include "modes_lcl.h"

#include <string.h>

#ifndef MODES_DEBUG

# ifndef NDEBUG

#  define NDEBUG

# endif

#endif

#include <assert.h>

typedef struct {

	void      *key1, *key2;

	block128_f block1,block2;

} XTS128_CONTEXT;

int CRYPTO_xts128_encrypt(const XTS128_CONTEXT *ctx, u64 secno,

	const unsigned char *inp, unsigned char *out,

	size_t len, int enc)

{

	const union { long one; char little; } is_endian = {1};

	union { u64 u[2]; u32 d[4]; u8 c[16]; } tweak, scratch;

	if (len<16) return -1;

	if (is_endian.little) {

		tweak.u[0] = secno;

		tweak.u[1] = 0;

	}

	else {

		PUTU32(tweak.c,secno);

		PUTU32(tweak.c+4,secno>>32);

		tweak.u[1] = 0;

	}

	(*ctx->block2)(tweak.c,tweak.c,ctx->key2);

	if (!enc && len%16) len-=16;

	while (len>=16) {

#if defined(STRICT_ALIGNMENT)

		memcpy(scratch.c,inp,16);

		scratch.u[0] ^= tweak.u[0];

		scratch.u[1] ^= tweak.u[1];

#else

		scratch.u[0] = ((u64*)inp)[0]^tweak.u[0];

		scratch.u[1] = ((u64*)inp)[1]^tweak.u[1];

#endif

		(*ctx->block1)(scratch.c,scratch.c,ctx->key1);

		scratch.u[0] ^= tweak.u[0];

		scratch.u[1] ^= tweak.u[1];

		memcpy(out,scratch.c,16);

		inp += 16;

		out += 16;

		len -= 16;

		if (is_endian.little) {

			unsigned int carry,res;

			res = 0x87&(((int)tweak.d[3])>>31);

			carry = tweak.u[0]>>63;

			tweak.u[0] = (tweak.u[0]<<1)^res;

			tweak.u[1] = (tweak.u[1]<<1)|carry;

		}

		else {

			unsigned int carry,c,i;

			for (carry=0,i=0;i<16;++i) {

				c = tweak.c[i];

				tweak.c[i] = (c<<1)|carry;

				carry = c>>7;

			}

			tweak.c[0] ^= 0x87&(0-carry);

		}

	}

	if (len) {

		unsigned int i;

		if (enc) {

			for (i=0;i<len;++i) {

				u8 c = inp[i];

				out[i] = scratch.c[i];

				scratch.c[i] = c;

			}

			scratch.u[0] ^= tweak.u[0];

			scratch.u[1] ^= tweak.u[1];

			(*ctx->block1)(scratch.c,scratch.c,ctx->key1);

			scratch.u[0] ^= tweak.u[0];

			scratch.u[1] ^= tweak.u[1];

			memcpy(out-16,scratch.c,16);

		}

		else {

			union { u64 u[2]; u8 c[16]; } tweak1;

			if (is_endian.little) {

				unsigned int carry,res;

				res = 0x87&(((int)tweak.d[3])>>31);

				carry = tweak.u[0]>>63;

				tweak1.u[0] = (tweak.u[0]<<1)^res;

				tweak1.u[1] = (tweak.u[1]<<1)|carry;

			}

			else {

				unsigned int carry,c;

				for (carry=0,i=0;i<16;++i) {

					c = tweak.c[i];

					tweak1.c[i] = (c<<1)|carry;

					carry = c>>7;

				}

				tweak1.c[0] ^= 0x87&(0-carry);

			}

#if defined(STRICT_ALIGNMENT)

			memcpy(scratch.c,inp,16);

			scratch.u[0] ^= tweak1.u[0];

			scratch.u[1] ^= tweak1.u[1];

#else

			scratch.u[0] = ((u64*)inp)[0]^tweak1.u[0];

			scratch.u[1] = ((u64*)inp)[1]^tweak1.u[1];

#endif

			(*ctx->block1)(scratch.c,scratch.c,ctx->key1);

			scratch.u[0] ^= tweak1.u[0];

			scratch.u[1] ^= tweak1.u[1];

			for (i=0;i<len;++i) {

				u8 c = inp[16+i];

				out[16+i] = scratch.c[i];

				scratch.c[i] = c;

			}

			scratch.u[0] ^= tweak.u[0];

			scratch.u[1] ^= tweak.u[1];

			(*ctx->block1)(scratch.c,scratch.c,ctx->key1);

			scratch.u[0] ^= tweak.u[0];

			scratch.u[1] ^= tweak.u[1];

			memcpy (out,scratch.c,16);

		}

	}

	return 0;

}