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

 * 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>

int CRYPTO_xts128_encrypt(const XTS128_CONTEXT *ctx,

                          const unsigned char iv[16],

                          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;

    unsigned int i;

    if (len < 16)

        return -1;

    memcpy(tweak.c, iv, 16);

    (*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);

#if defined(STRICT_ALIGNMENT)

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

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

        memcpy(out, scratch.c, 16);

#else

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

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

#endif

        inp += 16;

        out += 16;

        len -= 16;

        if (len == 0)

            return 0;

        if (is_endian.little) {

            unsigned int carry, res;

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

            carry = (unsigned int)(tweak.u[0] >> 63);

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

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

        } else {

            size_t c;

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

                /*

                 * + substitutes for |, because c is 1 bit

                 */

                c += ((size_t)tweak.c[i]) << 1;

                tweak.c[i] = (u8)c;

                c = c >> 8;

            }

            tweak.c[0] ^= (u8)(0x87 & (0 - c));

        }

    }

    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 = (unsigned int)(tweak.u[0] >> 63);

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

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

        } else {

            size_t c;

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

                /*

                 * + substitutes for |, because c is 1 bit

                 */

                c += ((size_t)tweak.c[i]) << 1;

                tweak1.c[i] = (u8)c;

                c = c >> 8;

            }

            tweak1.c[0] ^= (u8)(0x87 & (0 - c));

        }

#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);

#if defined(STRICT_ALIGNMENT)

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

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

        memcpy(out, scratch.c, 16);

#else

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

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

#endif

    }

    return 0;

}