1 /* 2 * An implementation of the ARCFOUR algorithm 3 * 4 * Copyright The Mbed TLS Contributors 5 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later 6 * 7 * This file is provided under the Apache License 2.0, or the 8 * GNU General Public License v2.0 or later. 9 * 10 * ********** 11 * Apache License 2.0: 12 * 13 * Licensed under the Apache License, Version 2.0 (the "License"); you may 14 * not use this file except in compliance with the License. 15 * You may obtain a copy of the License at 16 * 17 * http://www.apache.org/licenses/LICENSE-2.0 18 * 19 * Unless required by applicable law or agreed to in writing, software 20 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 21 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 22 * See the License for the specific language governing permissions and 23 * limitations under the License. 24 * 25 * ********** 26 * 27 * ********** 28 * GNU General Public License v2.0 or later: 29 * 30 * This program is free software; you can redistribute it and/or modify 31 * it under the terms of the GNU General Public License as published by 32 * the Free Software Foundation; either version 2 of the License, or 33 * (at your option) any later version. 34 * 35 * This program is distributed in the hope that it will be useful, 36 * but WITHOUT ANY WARRANTY; without even the implied warranty of 37 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 38 * GNU General Public License for more details. 39 * 40 * You should have received a copy of the GNU General Public License along 41 * with this program; if not, write to the Free Software Foundation, Inc., 42 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 43 * 44 * ********** 45 */ 46 /* 47 * The ARCFOUR algorithm was publicly disclosed on 94/09. 48 * 49 * http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0 50 */ 51 52 #if !defined(MBEDTLS_CONFIG_FILE) 53 #include "mbedtls/config.h" 54 #else 55 #include MBEDTLS_CONFIG_FILE 56 #endif 57 58 #if defined(MBEDTLS_ARC4_C) 59 60 #include "mbedtls/arc4.h" 61 #include "mbedtls/platform_util.h" 62 63 #include <string.h> 64 65 #if defined(MBEDTLS_SELF_TEST) 66 #if defined(MBEDTLS_PLATFORM_C) 67 #include "mbedtls/platform.h" 68 #else 69 #include <stdio.h> 70 #define mbedtls_printf printf 71 #endif /* MBEDTLS_PLATFORM_C */ 72 #endif /* MBEDTLS_SELF_TEST */ 73 74 #if !defined(MBEDTLS_ARC4_ALT) 75 76 void mbedtls_arc4_init( mbedtls_arc4_context *ctx ) 77 { 78 memset( ctx, 0, sizeof( mbedtls_arc4_context ) ); 79 } 80 81 void mbedtls_arc4_free( mbedtls_arc4_context *ctx ) 82 { 83 if( ctx == NULL ) 84 return; 85 86 mbedtls_platform_zeroize( ctx, sizeof( mbedtls_arc4_context ) ); 87 } 88 89 /* 90 * ARC4 key schedule 91 */ 92 void mbedtls_arc4_setup( mbedtls_arc4_context *ctx, const unsigned char *key, 93 unsigned int keylen ) 94 { 95 int i, j, a; 96 unsigned int k; 97 unsigned char *m; 98 99 ctx->x = 0; 100 ctx->y = 0; 101 m = ctx->m; 102 103 for( i = 0; i < 256; i++ ) 104 m[i] = (unsigned char) i; 105 106 j = k = 0; 107 108 for( i = 0; i < 256; i++, k++ ) 109 { 110 if( k >= keylen ) k = 0; 111 112 a = m[i]; 113 j = ( j + a + key[k] ) & 0xFF; 114 m[i] = m[j]; 115 m[j] = (unsigned char) a; 116 } 117 } 118 119 /* 120 * ARC4 cipher function 121 */ 122 int mbedtls_arc4_crypt( mbedtls_arc4_context *ctx, size_t length, const unsigned char *input, 123 unsigned char *output ) 124 { 125 int x, y, a, b; 126 size_t i; 127 unsigned char *m; 128 129 x = ctx->x; 130 y = ctx->y; 131 m = ctx->m; 132 133 for( i = 0; i < length; i++ ) 134 { 135 x = ( x + 1 ) & 0xFF; a = m[x]; 136 y = ( y + a ) & 0xFF; b = m[y]; 137 138 m[x] = (unsigned char) b; 139 m[y] = (unsigned char) a; 140 141 output[i] = (unsigned char) 142 ( input[i] ^ m[(unsigned char)( a + b )] ); 143 } 144 145 ctx->x = x; 146 ctx->y = y; 147 148 return( 0 ); 149 } 150 151 #endif /* !MBEDTLS_ARC4_ALT */ 152 153 #if defined(MBEDTLS_SELF_TEST) 154 /* 155 * ARC4 tests vectors as posted by Eric Rescorla in sep. 1994: 156 * 157 * http://groups.google.com/group/comp.security.misc/msg/10a300c9d21afca0 158 */ 159 static const unsigned char arc4_test_key[3][8] = 160 { 161 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF }, 162 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF }, 163 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 } 164 }; 165 166 static const unsigned char arc4_test_pt[3][8] = 167 { 168 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF }, 169 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, 170 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 } 171 }; 172 173 static const unsigned char arc4_test_ct[3][8] = 174 { 175 { 0x75, 0xB7, 0x87, 0x80, 0x99, 0xE0, 0xC5, 0x96 }, 176 { 0x74, 0x94, 0xC2, 0xE7, 0x10, 0x4B, 0x08, 0x79 }, 177 { 0xDE, 0x18, 0x89, 0x41, 0xA3, 0x37, 0x5D, 0x3A } 178 }; 179 180 /* 181 * Checkup routine 182 */ 183 int mbedtls_arc4_self_test( int verbose ) 184 { 185 int i, ret = 0; 186 unsigned char ibuf[8]; 187 unsigned char obuf[8]; 188 mbedtls_arc4_context ctx; 189 190 mbedtls_arc4_init( &ctx ); 191 192 for( i = 0; i < 3; i++ ) 193 { 194 if( verbose != 0 ) 195 mbedtls_printf( " ARC4 test #%d: ", i + 1 ); 196 197 memcpy( ibuf, arc4_test_pt[i], 8 ); 198 199 mbedtls_arc4_setup( &ctx, arc4_test_key[i], 8 ); 200 mbedtls_arc4_crypt( &ctx, 8, ibuf, obuf ); 201 202 if( memcmp( obuf, arc4_test_ct[i], 8 ) != 0 ) 203 { 204 if( verbose != 0 ) 205 mbedtls_printf( "failed\n" ); 206 207 ret = 1; 208 goto exit; 209 } 210 211 if( verbose != 0 ) 212 mbedtls_printf( "passed\n" ); 213 } 214 215 if( verbose != 0 ) 216 mbedtls_printf( "\n" ); 217 218 exit: 219 mbedtls_arc4_free( &ctx ); 220 221 return( ret ); 222 } 223 224 #endif /* MBEDTLS_SELF_TEST */ 225 226 #endif /* MBEDTLS_ARC4_C */ 227