179 lines
4 KiB
C
179 lines
4 KiB
C
/*
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* An implementation of the ARCFOUR algorithm
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*
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* Copyright (C) 2006-2014, Brainspark B.V.
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*
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* This file is part of PolarSSL (http://www.polarssl.org)
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* Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
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*
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* All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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/*
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* The ARCFOUR algorithm was publicly disclosed on 94/09.
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*
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* http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0
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*/
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#include "polarssl/config.h"
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#if defined(POLARSSL_ARC4_C)
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#include "polarssl/arc4.h"
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#if defined(POLARSSL_PLATFORM_C)
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#include "polarssl/platform.h"
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#else
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#define polarssl_printf printf
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#endif
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#if !defined(POLARSSL_ARC4_ALT)
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/*
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* ARC4 key schedule
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*/
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void arc4_setup( arc4_context *ctx, const unsigned char *key, unsigned int keylen )
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{
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int i, j, a;
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unsigned int k;
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unsigned char *m;
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ctx->x = 0;
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ctx->y = 0;
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m = ctx->m;
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for( i = 0; i < 256; i++ )
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m[i] = (unsigned char) i;
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j = k = 0;
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for( i = 0; i < 256; i++, k++ )
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{
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if( k >= keylen ) k = 0;
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a = m[i];
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j = ( j + a + key[k] ) & 0xFF;
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m[i] = m[j];
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m[j] = (unsigned char) a;
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}
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}
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/*
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* ARC4 cipher function
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*/
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int arc4_crypt( arc4_context *ctx, size_t length, const unsigned char *input,
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unsigned char *output )
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{
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int x, y, a, b;
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size_t i;
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unsigned char *m;
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x = ctx->x;
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y = ctx->y;
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m = ctx->m;
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for( i = 0; i < length; i++ )
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{
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x = ( x + 1 ) & 0xFF; a = m[x];
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y = ( y + a ) & 0xFF; b = m[y];
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m[x] = (unsigned char) b;
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m[y] = (unsigned char) a;
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output[i] = (unsigned char)
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( input[i] ^ m[(unsigned char)( a + b )] );
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}
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ctx->x = x;
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ctx->y = y;
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return( 0 );
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}
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#endif /* !POLARSSL_ARC4_ALT */
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#if defined(POLARSSL_SELF_TEST)
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#include <string.h>
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#include <stdio.h>
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/*
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* ARC4 tests vectors as posted by Eric Rescorla in sep. 1994:
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*
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* http://groups.google.com/group/comp.security.misc/msg/10a300c9d21afca0
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*/
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static const unsigned char arc4_test_key[3][8] =
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{
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{ 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
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{ 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
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{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
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};
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static const unsigned char arc4_test_pt[3][8] =
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{
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{ 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
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{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
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{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
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};
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static const unsigned char arc4_test_ct[3][8] =
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{
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{ 0x75, 0xB7, 0x87, 0x80, 0x99, 0xE0, 0xC5, 0x96 },
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{ 0x74, 0x94, 0xC2, 0xE7, 0x10, 0x4B, 0x08, 0x79 },
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{ 0xDE, 0x18, 0x89, 0x41, 0xA3, 0x37, 0x5D, 0x3A }
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};
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/*
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* Checkup routine
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*/
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int arc4_self_test( int verbose )
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{
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int i;
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unsigned char ibuf[8];
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unsigned char obuf[8];
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arc4_context ctx;
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for( i = 0; i < 3; i++ )
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{
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if( verbose != 0 )
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polarssl_printf( " ARC4 test #%d: ", i + 1 );
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memcpy( ibuf, arc4_test_pt[i], 8 );
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arc4_setup( &ctx, arc4_test_key[i], 8 );
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arc4_crypt( &ctx, 8, ibuf, obuf );
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if( memcmp( obuf, arc4_test_ct[i], 8 ) != 0 )
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{
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if( verbose != 0 )
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polarssl_printf( "failed\n" );
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return( 1 );
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}
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if( verbose != 0 )
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polarssl_printf( "passed\n" );
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}
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if( verbose != 0 )
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polarssl_printf( "\n" );
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return( 0 );
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}
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#endif
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#endif
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