1 /* 2 * An implementation of the ARCFOUR algorithm 3 * 4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved 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 * This file is part of mbed TLS (https://tls.mbed.org) 47 */ 48 /* 49 * The ARCFOUR algorithm was publicly disclosed on 94/09. 50 * 51 * http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0 52 */ 53 54 #if !defined(MBEDTLS_CONFIG_FILE) 55 #include "mbedtls/config.h" 56 #else 57 #include MBEDTLS_CONFIG_FILE 58 #endif 59 60 #if defined(MBEDTLS_ARC4_C) 61 62 #include "mbedtls/arc4.h" 63 64 #include <string.h> 65 66 #if defined(MBEDTLS_SELF_TEST) 67 #if defined(MBEDTLS_PLATFORM_C) 68 #include "mbedtls/platform.h" 69 #else 70 #include <stdio.h> 71 #define mbedtls_printf printf 72 #endif /* MBEDTLS_PLATFORM_C */ 73 #endif /* MBEDTLS_SELF_TEST */ 74 75 #if !defined(MBEDTLS_ARC4_ALT) 76 77 /* Implementation that should never be optimized out by the compiler */ 78 static void mbedtls_zeroize( void *v, size_t n ) { 79 volatile unsigned char *p = (unsigned char*)v; while( n-- ) *p++ = 0; 80 } 81 82 void mbedtls_arc4_init( mbedtls_arc4_context *ctx ) 83 { 84 memset( ctx, 0, sizeof( mbedtls_arc4_context ) ); 85 } 86 87 void mbedtls_arc4_free( mbedtls_arc4_context *ctx ) 88 { 89 if( ctx == NULL ) 90 return; 91 92 mbedtls_zeroize( ctx, sizeof( mbedtls_arc4_context ) ); 93 } 94 95 /* 96 * ARC4 key schedule 97 */ 98 void mbedtls_arc4_setup( mbedtls_arc4_context *ctx, const unsigned char *key, 99 unsigned int keylen ) 100 { 101 int i, j, a; 102 unsigned int k; 103 unsigned char *m; 104 105 ctx->x = 0; 106 ctx->y = 0; 107 m = ctx->m; 108 109 for( i = 0; i < 256; i++ ) 110 m[i] = (unsigned char) i; 111 112 j = k = 0; 113 114 for( i = 0; i < 256; i++, k++ ) 115 { 116 if( k >= keylen ) k = 0; 117 118 a = m[i]; 119 j = ( j + a + key[k] ) & 0xFF; 120 m[i] = m[j]; 121 m[j] = (unsigned char) a; 122 } 123 } 124 125 /* 126 * ARC4 cipher function 127 */ 128 int mbedtls_arc4_crypt( mbedtls_arc4_context *ctx, size_t length, const unsigned char *input, 129 unsigned char *output ) 130 { 131 int x, y, a, b; 132 size_t i; 133 unsigned char *m; 134 135 x = ctx->x; 136 y = ctx->y; 137 m = ctx->m; 138 139 for( i = 0; i < length; i++ ) 140 { 141 x = ( x + 1 ) & 0xFF; a = m[x]; 142 y = ( y + a ) & 0xFF; b = m[y]; 143 144 m[x] = (unsigned char) b; 145 m[y] = (unsigned char) a; 146 147 output[i] = (unsigned char) 148 ( input[i] ^ m[(unsigned char)( a + b )] ); 149 } 150 151 ctx->x = x; 152 ctx->y = y; 153 154 return( 0 ); 155 } 156 157 #endif /* !MBEDTLS_ARC4_ALT */ 158 159 #if defined(MBEDTLS_SELF_TEST) 160 /* 161 * ARC4 tests vectors as posted by Eric Rescorla in sep. 1994: 162 * 163 * http://groups.google.com/group/comp.security.misc/msg/10a300c9d21afca0 164 */ 165 static const unsigned char arc4_test_key[3][8] = 166 { 167 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF }, 168 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF }, 169 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 } 170 }; 171 172 static const unsigned char arc4_test_pt[3][8] = 173 { 174 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF }, 175 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, 176 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 } 177 }; 178 179 static const unsigned char arc4_test_ct[3][8] = 180 { 181 { 0x75, 0xB7, 0x87, 0x80, 0x99, 0xE0, 0xC5, 0x96 }, 182 { 0x74, 0x94, 0xC2, 0xE7, 0x10, 0x4B, 0x08, 0x79 }, 183 { 0xDE, 0x18, 0x89, 0x41, 0xA3, 0x37, 0x5D, 0x3A } 184 }; 185 186 /* 187 * Checkup routine 188 */ 189 int mbedtls_arc4_self_test( int verbose ) 190 { 191 int i, ret = 0; 192 unsigned char ibuf[8]; 193 unsigned char obuf[8]; 194 mbedtls_arc4_context ctx; 195 196 mbedtls_arc4_init( &ctx ); 197 198 for( i = 0; i < 3; i++ ) 199 { 200 if( verbose != 0 ) 201 mbedtls_printf( " ARC4 test #%d: ", i + 1 ); 202 203 memcpy( ibuf, arc4_test_pt[i], 8 ); 204 205 mbedtls_arc4_setup( &ctx, arc4_test_key[i], 8 ); 206 mbedtls_arc4_crypt( &ctx, 8, ibuf, obuf ); 207 208 if( memcmp( obuf, arc4_test_ct[i], 8 ) != 0 ) 209 { 210 if( verbose != 0 ) 211 mbedtls_printf( "failed\n" ); 212 213 ret = 1; 214 goto exit; 215 } 216 217 if( verbose != 0 ) 218 mbedtls_printf( "passed\n" ); 219 } 220 221 if( verbose != 0 ) 222 mbedtls_printf( "\n" ); 223 224 exit: 225 mbedtls_arc4_free( &ctx ); 226 227 return( ret ); 228 } 229 230 #endif /* MBEDTLS_SELF_TEST */ 231 232 #endif /* MBEDTLS_ARC4_C */ 233