/*
 *  An 32-bit implementation of the XTEA algorithm
 *
 *  Copyright (C) 2009  Paul Bakker <polarssl_maintainer at polarssl dot org>
 *
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *  
 *    * Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *    * 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.
 *    * Neither the names of PolarSSL or XySSL nor the names of its contributors
 *      may be used to endorse or promote products derived from this software
 *      without specific prior written permission.
 *  
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *  "AS IS" AND ANY EXPRESS 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 COPYRIGHT
 *  OWNER OR 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 "polarssl/config.h"

#if defined(POLARSSL_XTEA_C)

#include "polarssl/xtea.h"

#include <string.h>

/*
 * 32-bit integer manipulation macros (big endian)
 */
#ifndef GET_ULONG_BE
#define GET_ULONG_BE(n,b,i)                             \
{                                                       \
    (n) = ( (unsigned long) (b)[(i)    ] << 24 )        \
	| ( (unsigned long) (b)[(i) + 1] << 16 )        \
	| ( (unsigned long) (b)[(i) + 2] <<  8 )        \
	| ( (unsigned long) (b)[(i) + 3]       );       \
}
#endif

#ifndef PUT_ULONG_BE
#define PUT_ULONG_BE(n,b,i)                             \
{                                                       \
    (b)[(i)    ] = (unsigned char) ( (n) >> 24 );       \
    (b)[(i) + 1] = (unsigned char) ( (n) >> 16 );       \
    (b)[(i) + 2] = (unsigned char) ( (n) >>  8 );       \
    (b)[(i) + 3] = (unsigned char) ( (n)       );       \
}
#endif

/*
 * XTEA key schedule
 */
void xtea_setup( xtea_context *ctx, unsigned char key[16] )
{
    int i;

    memset(ctx, 0, sizeof(xtea_context));

    for( i = 0; i < 4; i++ )
    {
    	GET_ULONG_BE( ctx->k[i], key, i << 2 );
    }
}

/*
 * XTEA encrypt function
 */
void xtea_crypt_ecb( xtea_context *ctx, int mode, unsigned char input[8], unsigned char output[8])
{
    unsigned long *k, v0, v1, i;

    k = ctx->k;
    
    GET_ULONG_BE( v0, input, 0 );
    GET_ULONG_BE( v1, input, 4 );

    if( mode == XTEA_ENCRYPT )
    {
	    unsigned long sum = 0, delta = 0x9E3779B9;

	    for( i = 0; i < 32; i++ )
	    {
		    v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + k[sum & 3]);
		    sum += delta;
		    v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + k[(sum>>11) & 3]);
	    }
    }
    else /* XTEA_DECRYPT */
    {
	    unsigned long delta = 0x9E3779B9, sum = delta * 32;

	    for( i = 0; i < 32; i++ )
	    {
		    v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + k[(sum>>11) & 3]);
		    sum -= delta;
		    v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + k[sum & 3]);
	    }
    }

    PUT_ULONG_BE( v0, output, 0 );
    PUT_ULONG_BE( v1, output, 4 );
}

#if defined(POLARSSL_SELF_TEST)

#include <string.h>
#include <stdio.h>

/*
 * XTEA tests vectors (non-official)
 */

static const unsigned char xtea_test_key[6][16] =
{
   { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
   { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
   { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
   { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
   { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
   { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
};

static const unsigned char xtea_test_pt[6][8] =
{
    { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
    { 0x5a, 0x5b, 0x6e, 0x27, 0x89, 0x48, 0xd7, 0x7f },
    { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
    { 0x70, 0xe1, 0x22, 0x5d, 0x6e, 0x4e, 0x76, 0x55 }
};

static const unsigned char xtea_test_ct[6][8] =
{
    { 0x49, 0x7d, 0xf3, 0xd0, 0x72, 0x61, 0x2c, 0xb5 },
    { 0xe7, 0x8f, 0x2d, 0x13, 0x74, 0x43, 0x41, 0xd8 },
    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
    { 0xa0, 0x39, 0x05, 0x89, 0xf8, 0xb8, 0xef, 0xa5 },
    { 0xed, 0x23, 0x37, 0x5a, 0x82, 0x1a, 0x8c, 0x2d },
    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }
};

/*
 * Checkup routine
 */
int xtea_self_test( int verbose )
{
    int i;
    unsigned char buf[8];
    xtea_context ctx;

    for( i = 0; i < 6; i++ )
    {
        if( verbose != 0 )
            printf( "  XTEA test #%d: ", i + 1 );

        memcpy( buf, xtea_test_pt[i], 8 );

        xtea_setup( &ctx, (unsigned char *) xtea_test_key[i] );
        xtea_crypt_ecb( &ctx, XTEA_ENCRYPT, buf, buf );

        if( memcmp( buf, xtea_test_ct[i], 8 ) != 0 )
        {
            if( verbose != 0 )
                printf( "failed\n" );

            return( 1 );
        }

        if( verbose != 0 )
            printf( "passed\n" );
    }

    if( verbose != 0 )
        printf( "\n" );

    return( 0 );
}

#endif

#endif