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/*

 *  An implementation of the ARCFOUR algorithm

 *

 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved

 *  SPDX-License-Identifier: GPL-2.0

 *

 *  This program is free software; you can redistribute it and/or modify

 *  it under the terms of the GNU General Public License as published by

 *  the Free Software Foundation; either version 2 of the License, or

 *  (at your option) any later version.

 *

 *  This program is distributed in the hope that it will be useful,

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *  GNU General Public License for more details.

 *

 *  You should have received a copy of the GNU General Public License along

 *  with this program; if not, write to the Free Software Foundation, Inc.,

 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 *  This file is part of mbed TLS (https://tls.mbed.org)

 */

/*

 *  The ARCFOUR algorithm was publicly disclosed on 94/09.

 *

 *  http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0

 */

#if !defined(MBEDTLS_CONFIG_FILE)

#include "mbedtls/config.h"

#else

#include MBEDTLS_CONFIG_FILE

#endif

#if defined(MBEDTLS_ARC4_C)

#include "mbedtls/arc4.h"

#include "mbedtls/platform_util.h"

#include 

#if defined(MBEDTLS_SELF_TEST)

#if defined(MBEDTLS_PLATFORM_C)

#include "mbedtls/platform.h"

#else

#include 

#define mbedtls_printf printf

#endif /* MBEDTLS_PLATFORM_C */

#endif /* MBEDTLS_SELF_TEST */

#if !defined(MBEDTLS_ARC4_ALT)

void mbedtls_arc4_init( mbedtls_arc4_context *ctx )

{

    memset( ctx, 0, sizeof( mbedtls_arc4_context ) );

}

void mbedtls_arc4_free( mbedtls_arc4_context *ctx )

{

    if( ctx == NULL )

        return;

    mbedtls_platform_zeroize( ctx, sizeof( mbedtls_arc4_context ) );

}

/*

 * ARC4 key schedule

 */

void mbedtls_arc4_setup( mbedtls_arc4_context *ctx, const unsigned char *key,

                 unsigned int keylen )

{

    int i, j, a;

    unsigned int k;

    unsigned char *m;

    ctx->x = 0;

    ctx->y = 0;

    m = ctx->m;

    for( i = 0; i < 256; i++ )

        m[i] = (unsigned char) i;

    j = k = 0;

    for( i = 0; i < 256; i++, k++ )

    {

        if( k >= keylen ) k = 0;

        a = m[i];

        j = ( j + a + key[k] ) & 0xFF;

        m[i] = m[j];

        m[j] = (unsigned char) a;

    }

}

/*

 * ARC4 cipher function

 */

int mbedtls_arc4_crypt( mbedtls_arc4_context *ctx, size_t length, const unsigned char *input,

                unsigned char *output )

{

    int x, y, a, b;

    size_t i;

    unsigned char *m;

    x = ctx->x;

    y = ctx->y;

    m = ctx->m;

    for( i = 0; i < length; i++ )

    {

        x = ( x + 1 ) & 0xFF; a = m[x];

        y = ( y + a ) & 0xFF; b = m[y];

        m[x] = (unsigned char) b;

        m[y] = (unsigned char) a;

        output[i] = (unsigned char)

            ( input[i] ^ m[(unsigned char)( a + b )] );

    }

    ctx->x = x;

    ctx->y = y;

    return( 0 );

}

#endif /* !MBEDTLS_ARC4_ALT */

#if defined(MBEDTLS_SELF_TEST)

/*

 * ARC4 tests vectors as posted by Eric Rescorla in sep. 1994:

 *

 * http://groups.google.com/group/comp.security.misc/msg/10a300c9d21afca0

 */

static const unsigned char arc4_test_key[3][8] =

{

    { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },

    { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },

    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }

};

static const unsigned char arc4_test_pt[3][8] =

{

    { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },

    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },

    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }

};

static const unsigned char arc4_test_ct[3][8] =

{

    { 0x75, 0xB7, 0x87, 0x80, 0x99, 0xE0, 0xC5, 0x96 },

    { 0x74, 0x94, 0xC2, 0xE7, 0x10, 0x4B, 0x08, 0x79 },

    { 0xDE, 0x18, 0x89, 0x41, 0xA3, 0x37, 0x5D, 0x3A }

};

/*

 * Checkup routine

 */

int mbedtls_arc4_self_test( int verbose )

{

    int i, ret = 0;

    unsigned char ibuf[8];

    unsigned char obuf[8];

    mbedtls_arc4_context ctx;

    mbedtls_arc4_init( &ctx );

    for( i = 0; i < 3; i++ )

    {

        if( verbose != 0 )

            mbedtls_printf( "  ARC4 test #%d: ", i + 1 );

        memcpy( ibuf, arc4_test_pt[i], 8 );

        mbedtls_arc4_setup( &ctx, arc4_test_key[i], 8 );

        mbedtls_arc4_crypt( &ctx, 8, ibuf, obuf );

        if( memcmp( obuf, arc4_test_ct[i], 8 ) != 0 )

        {

            if( verbose != 0 )

                mbedtls_printf( "failed\n" );

            ret = 1;

            goto exit;

        }

        if( verbose != 0 )

            mbedtls_printf( "passed\n" );

    }

    if( verbose != 0 )

        mbedtls_printf( "\n" );

exit:

    mbedtls_arc4_free( &ctx );

    return( ret );

}

#endif /* MBEDTLS_SELF_TEST */

#endif /* MBEDTLS_ARC4_C */