2 * An implementation of the ARCFOUR algorithm
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4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
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5 * SPDX-License-Identifier: Apache-2.0
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7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
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8 * not use this file except in compliance with the License.
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9 * You may obtain a copy of the License at
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11 * http://www.apache.org/licenses/LICENSE-2.0
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13 * Unless required by applicable law or agreed to in writing, software
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14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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16 * See the License for the specific language governing permissions and
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17 * limitations under the License.
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19 * This file is part of mbed TLS (https://tls.mbed.org)
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22 * The ARCFOUR algorithm was publicly disclosed on 94/09.
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24 * http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0
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27 #if !defined(MBEDTLS_CONFIG_FILE)
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28 #include "mbedtls/config.h"
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30 #include MBEDTLS_CONFIG_FILE
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33 #if defined(MBEDTLS_ARC4_C)
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35 #include "mbedtls/arc4.h"
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36 #include "mbedtls/platform_util.h"
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40 #if defined(MBEDTLS_SELF_TEST)
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41 #if defined(MBEDTLS_PLATFORM_C)
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42 #include "mbedtls/platform.h"
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45 #define mbedtls_printf printf
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46 #endif /* MBEDTLS_PLATFORM_C */
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47 #endif /* MBEDTLS_SELF_TEST */
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49 #if !defined(MBEDTLS_ARC4_ALT)
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51 void mbedtls_arc4_init( mbedtls_arc4_context *ctx )
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53 memset( ctx, 0, sizeof( mbedtls_arc4_context ) );
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56 void mbedtls_arc4_free( mbedtls_arc4_context *ctx )
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61 mbedtls_platform_zeroize( ctx, sizeof( mbedtls_arc4_context ) );
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67 void mbedtls_arc4_setup( mbedtls_arc4_context *ctx, const unsigned char *key,
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68 unsigned int keylen )
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78 for( i = 0; i < 256; i++ )
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79 m[i] = (unsigned char) i;
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83 for( i = 0; i < 256; i++, k++ )
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85 if( k >= keylen ) k = 0;
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88 j = ( j + a + key[k] ) & 0xFF;
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90 m[j] = (unsigned char) a;
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95 * ARC4 cipher function
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97 int mbedtls_arc4_crypt( mbedtls_arc4_context *ctx, size_t length, const unsigned char *input,
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98 unsigned char *output )
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108 for( i = 0; i < length; i++ )
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110 x = ( x + 1 ) & 0xFF; a = m[x];
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111 y = ( y + a ) & 0xFF; b = m[y];
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113 m[x] = (unsigned char) b;
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114 m[y] = (unsigned char) a;
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116 output[i] = (unsigned char)
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117 ( input[i] ^ m[(unsigned char)( a + b )] );
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126 #endif /* !MBEDTLS_ARC4_ALT */
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128 #if defined(MBEDTLS_SELF_TEST)
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130 * ARC4 tests vectors as posted by Eric Rescorla in sep. 1994:
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132 * http://groups.google.com/group/comp.security.misc/msg/10a300c9d21afca0
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134 static const unsigned char arc4_test_key[3][8] =
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136 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
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137 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
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138 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
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141 static const unsigned char arc4_test_pt[3][8] =
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143 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
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144 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
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145 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
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148 static const unsigned char arc4_test_ct[3][8] =
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150 { 0x75, 0xB7, 0x87, 0x80, 0x99, 0xE0, 0xC5, 0x96 },
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151 { 0x74, 0x94, 0xC2, 0xE7, 0x10, 0x4B, 0x08, 0x79 },
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152 { 0xDE, 0x18, 0x89, 0x41, 0xA3, 0x37, 0x5D, 0x3A }
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158 int mbedtls_arc4_self_test( int verbose )
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161 unsigned char ibuf[8];
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162 unsigned char obuf[8];
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163 mbedtls_arc4_context ctx;
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165 mbedtls_arc4_init( &ctx );
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167 for( i = 0; i < 3; i++ )
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170 mbedtls_printf( " ARC4 test #%d: ", i + 1 );
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172 memcpy( ibuf, arc4_test_pt[i], 8 );
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174 mbedtls_arc4_setup( &ctx, arc4_test_key[i], 8 );
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175 mbedtls_arc4_crypt( &ctx, 8, ibuf, obuf );
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177 if( memcmp( obuf, arc4_test_ct[i], 8 ) != 0 )
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180 mbedtls_printf( "failed\n" );
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187 mbedtls_printf( "passed\n" );
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191 mbedtls_printf( "\n" );
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194 mbedtls_arc4_free( &ctx );
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199 #endif /* MBEDTLS_SELF_TEST */
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201 #endif /* MBEDTLS_ARC4_C */
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