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121 lines
2.6 KiB
C
121 lines
2.6 KiB
C
/*
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* An implementation of the ARCFOUR algorithm
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*
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* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* This file is part of mbed TLS (https://tls.mbed.org)
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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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#if !defined(MBEDTLS_CONFIG_FILE)
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#include "mbedtls/config.h"
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#else
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#include MBEDTLS_CONFIG_FILE
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#endif
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#if defined(MBEDTLS_ARC4_C)
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#include "mbedtls/arc4.h"
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#include <string.h>
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#if !defined(MBEDTLS_ARC4_ALT)
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#include "arc4_alt.h"
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void mbedtls_arc4_init( mbedtls_arc4_context *ctx )
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{
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memset( ctx, 0, sizeof( mbedtls_arc4_context ) );
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}
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void mbedtls_arc4_free( mbedtls_arc4_context *ctx )
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{
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if( ctx == NULL )
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return;
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mbedtls_zeroize( ctx, sizeof( mbedtls_arc4_context ) );
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}
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/*
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* ARC4 key schedule
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*/
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void mbedtls_arc4_setup( mbedtls_arc4_context *ctx, const unsigned char *key,
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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 mbedtls_arc4_crypt( mbedtls_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 /* !MBEDTLS_ARC4_ALT */
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#endif /* MBEDTLS_ARC4_C */
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