mbed TLS Build
Dependents: Encypting_Funcional
arc4.c
00001 /* 00002 * An implementation of the ARCFOUR algorithm 00003 * 00004 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved 00005 * SPDX-License-Identifier: Apache-2.0 00006 * 00007 * Licensed under the Apache License, Version 2.0 (the "License"); you may 00008 * not use this file except in compliance with the License. 00009 * You may obtain a copy of the License at 00010 * 00011 * http://www.apache.org/licenses/LICENSE-2.0 00012 * 00013 * Unless required by applicable law or agreed to in writing, software 00014 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 00015 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 00016 * See the License for the specific language governing permissions and 00017 * limitations under the License. 00018 * 00019 * This file is part of mbed TLS (https://tls.mbed.org) 00020 */ 00021 /* 00022 * The ARCFOUR algorithm was publicly disclosed on 94/09. 00023 * 00024 * http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0 00025 */ 00026 00027 #if !defined(MBEDTLS_CONFIG_FILE) 00028 #include "mbedtls/config.h" 00029 #else 00030 #include MBEDTLS_CONFIG_FILE 00031 #endif 00032 00033 #if defined(MBEDTLS_ARC4_C) 00034 00035 #include "mbedtls/arc4.h" 00036 00037 #include <string.h> 00038 00039 #if defined(MBEDTLS_SELF_TEST) 00040 #if defined(MBEDTLS_PLATFORM_C) 00041 #include "mbedtls/platform.h" 00042 #else 00043 #include <stdio.h> 00044 #define mbedtls_printf printf 00045 #endif /* MBEDTLS_PLATFORM_C */ 00046 #endif /* MBEDTLS_SELF_TEST */ 00047 00048 #if !defined(MBEDTLS_ARC4_ALT) 00049 00050 /* Implementation that should never be optimized out by the compiler */ 00051 static void mbedtls_zeroize( void *v, size_t n ) { 00052 volatile unsigned char *p = (unsigned char*)v; while( n-- ) *p++ = 0; 00053 } 00054 00055 void mbedtls_arc4_init( mbedtls_arc4_context *ctx ) 00056 { 00057 memset( ctx, 0, sizeof( mbedtls_arc4_context ) ); 00058 } 00059 00060 void mbedtls_arc4_free( mbedtls_arc4_context *ctx ) 00061 { 00062 if( ctx == NULL ) 00063 return; 00064 00065 mbedtls_zeroize( ctx, sizeof( mbedtls_arc4_context ) ); 00066 } 00067 00068 /* 00069 * ARC4 key schedule 00070 */ 00071 void mbedtls_arc4_setup( mbedtls_arc4_context *ctx, const unsigned char *key, 00072 unsigned int keylen ) 00073 { 00074 int i, j, a; 00075 unsigned int k; 00076 unsigned char *m; 00077 00078 ctx->x = 0; 00079 ctx->y = 0; 00080 m = ctx->m ; 00081 00082 for( i = 0; i < 256; i++ ) 00083 m[i] = (unsigned char) i; 00084 00085 j = k = 0; 00086 00087 for( i = 0; i < 256; i++, k++ ) 00088 { 00089 if( k >= keylen ) k = 0; 00090 00091 a = m[i]; 00092 j = ( j + a + key[k] ) & 0xFF; 00093 m[i] = m[j]; 00094 m[j] = (unsigned char) a; 00095 } 00096 } 00097 00098 /* 00099 * ARC4 cipher function 00100 */ 00101 int mbedtls_arc4_crypt( mbedtls_arc4_context *ctx, size_t length, const unsigned char *input, 00102 unsigned char *output ) 00103 { 00104 int x, y, a, b; 00105 size_t i; 00106 unsigned char *m; 00107 00108 x = ctx->x ; 00109 y = ctx->y ; 00110 m = ctx->m ; 00111 00112 for( i = 0; i < length; i++ ) 00113 { 00114 x = ( x + 1 ) & 0xFF; a = m[x]; 00115 y = ( y + a ) & 0xFF; b = m[y]; 00116 00117 m[x] = (unsigned char) b; 00118 m[y] = (unsigned char) a; 00119 00120 output[i] = (unsigned char) 00121 ( input[i] ^ m[(unsigned char)( a + b )] ); 00122 } 00123 00124 ctx->x = x; 00125 ctx->y = y; 00126 00127 return( 0 ); 00128 } 00129 00130 #endif /* !MBEDTLS_ARC4_ALT */ 00131 00132 #if defined(MBEDTLS_SELF_TEST) 00133 /* 00134 * ARC4 tests vectors as posted by Eric Rescorla in sep. 1994: 00135 * 00136 * http://groups.google.com/group/comp.security.misc/msg/10a300c9d21afca0 00137 */ 00138 static const unsigned char arc4_test_key[3][8] = 00139 { 00140 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF }, 00141 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF }, 00142 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 } 00143 }; 00144 00145 static const unsigned char arc4_test_pt[3][8] = 00146 { 00147 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF }, 00148 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, 00149 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 } 00150 }; 00151 00152 static const unsigned char arc4_test_ct[3][8] = 00153 { 00154 { 0x75, 0xB7, 0x87, 0x80, 0x99, 0xE0, 0xC5, 0x96 }, 00155 { 0x74, 0x94, 0xC2, 0xE7, 0x10, 0x4B, 0x08, 0x79 }, 00156 { 0xDE, 0x18, 0x89, 0x41, 0xA3, 0x37, 0x5D, 0x3A } 00157 }; 00158 00159 /* 00160 * Checkup routine 00161 */ 00162 int mbedtls_arc4_self_test( int verbose ) 00163 { 00164 int i, ret = 0; 00165 unsigned char ibuf[8]; 00166 unsigned char obuf[8]; 00167 mbedtls_arc4_context ctx; 00168 00169 mbedtls_arc4_init( &ctx ); 00170 00171 for( i = 0; i < 3; i++ ) 00172 { 00173 if( verbose != 0 ) 00174 mbedtls_printf( " ARC4 test #%d: ", i + 1 ); 00175 00176 memcpy( ibuf, arc4_test_pt[i], 8 ); 00177 00178 mbedtls_arc4_setup( &ctx, arc4_test_key[i], 8 ); 00179 mbedtls_arc4_crypt( &ctx, 8, ibuf, obuf ); 00180 00181 if( memcmp( obuf, arc4_test_ct[i], 8 ) != 0 ) 00182 { 00183 if( verbose != 0 ) 00184 mbedtls_printf( "failed\n" ); 00185 00186 ret = 1; 00187 goto exit; 00188 } 00189 00190 if( verbose != 0 ) 00191 mbedtls_printf( "passed\n" ); 00192 } 00193 00194 if( verbose != 0 ) 00195 mbedtls_printf( "\n" ); 00196 00197 exit: 00198 mbedtls_arc4_free( &ctx ); 00199 00200 return( ret ); 00201 } 00202 00203 #endif /* MBEDTLS_SELF_TEST */ 00204 00205 #endif /* MBEDTLS_ARC4_C */
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