1 | /*
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2 | * An implementation of the ARCFOUR algorithm
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3 | *
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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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6 | *
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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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10 | *
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11 | * http://www.apache.org/licenses/LICENSE-2.0
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12 | *
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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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18 | *
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19 | * This file is part of mbed TLS (https://tls.mbed.org)
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20 | */
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21 | /*
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22 | * The ARCFOUR algorithm was publicly disclosed on 94/09.
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23 | *
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24 | * http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0
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25 | */
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26 |
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27 | #if !defined(MBEDTLS_CONFIG_FILE)
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28 | #include "mbedtls/config.h"
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29 | #else
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30 | #include MBEDTLS_CONFIG_FILE
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31 | #endif
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32 |
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33 | #if defined(MBEDTLS_ARC4_C)
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34 |
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35 | #include "mbedtls/arc4.h"
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36 | #include "mbedtls/platform_util.h"
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37 |
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38 | #include <string.h>
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39 |
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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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43 | #else
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44 | #include <stdio.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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48 |
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49 | #if !defined(MBEDTLS_ARC4_ALT)
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50 |
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51 | void mbedtls_arc4_init( mbedtls_arc4_context *ctx )
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52 | {
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53 | memset( ctx, 0, sizeof( mbedtls_arc4_context ) );
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54 | }
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55 |
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56 | void mbedtls_arc4_free( mbedtls_arc4_context *ctx )
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57 | {
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58 | if( ctx == NULL )
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59 | return;
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60 |
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61 | mbedtls_platform_zeroize( ctx, sizeof( mbedtls_arc4_context ) );
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62 | }
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63 |
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64 | /*
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65 | * ARC4 key schedule
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66 | */
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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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69 | {
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70 | int i, j, a;
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71 | unsigned int k;
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72 | unsigned char *m;
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73 |
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74 | ctx->x = 0;
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75 | ctx->y = 0;
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76 | m = ctx->m;
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77 |
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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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80 |
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81 | j = k = 0;
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82 |
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83 | for( i = 0; i < 256; i++, k++ )
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84 | {
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85 | if( k >= keylen ) k = 0;
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86 |
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87 | a = m[i];
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88 | j = ( j + a + key[k] ) & 0xFF;
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89 | m[i] = m[j];
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90 | m[j] = (unsigned char) a;
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91 | }
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92 | }
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93 |
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94 | /*
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95 | * ARC4 cipher function
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96 | */
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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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99 | {
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100 | int x, y, a, b;
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101 | size_t i;
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102 | unsigned char *m;
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103 |
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104 | x = ctx->x;
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105 | y = ctx->y;
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106 | m = ctx->m;
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107 |
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108 | for( i = 0; i < length; i++ )
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109 | {
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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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112 |
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113 | m[x] = (unsigned char) b;
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114 | m[y] = (unsigned char) a;
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115 |
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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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118 | }
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119 |
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120 | ctx->x = x;
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121 | ctx->y = y;
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122 |
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123 | return( 0 );
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124 | }
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125 |
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126 | #endif /* !MBEDTLS_ARC4_ALT */
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127 |
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128 | #if defined(MBEDTLS_SELF_TEST)
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129 | /*
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130 | * ARC4 tests vectors as posted by Eric Rescorla in sep. 1994:
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131 | *
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132 | * http://groups.google.com/group/comp.security.misc/msg/10a300c9d21afca0
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133 | */
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134 | static const unsigned char arc4_test_key[3][8] =
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135 | {
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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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139 | };
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140 |
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141 | static const unsigned char arc4_test_pt[3][8] =
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142 | {
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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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146 | };
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147 |
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148 | static const unsigned char arc4_test_ct[3][8] =
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149 | {
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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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153 | };
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154 |
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155 | /*
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156 | * Checkup routine
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157 | */
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158 | int mbedtls_arc4_self_test( int verbose )
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159 | {
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160 | int i, ret = 0;
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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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164 |
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165 | mbedtls_arc4_init( &ctx );
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166 |
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167 | for( i = 0; i < 3; i++ )
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168 | {
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169 | if( verbose != 0 )
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170 | mbedtls_printf( " ARC4 test #%d: ", i + 1 );
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171 |
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172 | memcpy( ibuf, arc4_test_pt[i], 8 );
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173 |
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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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176 |
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177 | if( memcmp( obuf, arc4_test_ct[i], 8 ) != 0 )
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178 | {
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179 | if( verbose != 0 )
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180 | mbedtls_printf( "failed\n" );
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181 |
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182 | ret = 1;
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183 | goto exit;
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184 | }
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185 |
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186 | if( verbose != 0 )
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187 | mbedtls_printf( "passed\n" );
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188 | }
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189 |
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190 | if( verbose != 0 )
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191 | mbedtls_printf( "\n" );
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192 |
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193 | exit:
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194 | mbedtls_arc4_free( &ctx );
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195 |
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196 | return( ret );
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197 | }
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198 |
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199 | #endif /* MBEDTLS_SELF_TEST */
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200 |
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201 | #endif /* MBEDTLS_ARC4_C */
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