00001 /* 00002 * An implementation of the ARCFOUR algorithm 00003 * 00004 * Copyright (C) 2006-2007 Christophe Devine 00005 * 00006 * This program is free software; you can redistribute it and/or modify 00007 * it under the terms of the GNU General Public License as published by 00008 * the Free Software Foundation; either version 2 of the License, or 00009 * (at your option) any later version. 00010 * 00011 * This program is distributed in the hope that it will be useful, 00012 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 * GNU General Public License for more details. 00015 * 00016 * You should have received a copy of the GNU General Public License along 00017 * with this program; if not, write to the Free Software Foundation, Inc., 00018 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 00019 */ 00020 /* 00021 * The ARCFOUR algorithm was publicly disclosed on 94/09. 00022 * 00023 * http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0 00024 */ 00025 00026 #include "xyssl/config.h" 00027 00028 #if defined(XYSSL_ARC4_C) 00029 00030 #include "xyssl/arc4.h" 00031 00032 /* 00033 * ARC4 key schedule 00034 */ 00035 void arc4_setup( arc4_context *ctx, unsigned char *key, int keylen ) 00036 { 00037 int i, j, k, a; 00038 unsigned char *m; 00039 00040 ctx->x = 0; 00041 ctx->y = 0; 00042 m = ctx->m; 00043 00044 for( i = 0; i < 256; i++ ) 00045 m[i] = (unsigned char) i; 00046 00047 j = k = 0; 00048 00049 for( i = 0; i < 256; i++, k++ ) 00050 { 00051 if( k >= keylen ) k = 0; 00052 00053 a = m[i]; 00054 j = ( j + a + key[k] ) & 0xFF; 00055 m[i] = m[j]; 00056 m[j] = (unsigned char) a; 00057 } 00058 } 00059 00060 /* 00061 * ARC4 cipher function 00062 */ 00063 void arc4_crypt( arc4_context *ctx, unsigned char *buf, int buflen ) 00064 { 00065 int i, x, y, a, b; 00066 unsigned char *m; 00067 00068 x = ctx->x; 00069 y = ctx->y; 00070 m = ctx->m; 00071 00072 for( i = 0; i < buflen; i++ ) 00073 { 00074 x = ( x + 1 ) & 0xFF; a = m[x]; 00075 y = ( y + a ) & 0xFF; b = m[y]; 00076 00077 m[x] = (unsigned char) b; 00078 m[y] = (unsigned char) a; 00079 00080 buf[i] = (unsigned char) 00081 ( buf[i] ^ m[(unsigned char)( a + b )] ); 00082 } 00083 00084 ctx->x = x; 00085 ctx->y = y; 00086 } 00087 00088 #if defined(XYSSL_SELF_TEST) 00089 00090 #include <string.h> 00091 #include <stdio.h> 00092 00093 /* 00094 * ARC4 tests vectors as posted by Eric Rescorla in sep. 1994: 00095 * 00096 * http://groups.google.com/group/comp.security.misc/msg/10a300c9d21afca0 00097 */ 00098 static const unsigned char arc4_test_key[3][8] = 00099 { 00100 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF }, 00101 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF }, 00102 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 } 00103 }; 00104 00105 static const unsigned char arc4_test_pt[3][8] = 00106 { 00107 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF }, 00108 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, 00109 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 } 00110 }; 00111 00112 static const unsigned char arc4_test_ct[3][8] = 00113 { 00114 { 0x75, 0xB7, 0x87, 0x80, 0x99, 0xE0, 0xC5, 0x96 }, 00115 { 0x74, 0x94, 0xC2, 0xE7, 0x10, 0x4B, 0x08, 0x79 }, 00116 { 0xDE, 0x18, 0x89, 0x41, 0xA3, 0x37, 0x5D, 0x3A } 00117 }; 00118 00119 /* 00120 * Checkup routine 00121 */ 00122 int arc4_self_test( int verbose ) 00123 { 00124 int i; 00125 unsigned char buf[8]; 00126 arc4_context ctx; 00127 00128 for( i = 0; i < 3; i++ ) 00129 { 00130 if( verbose != 0 ) 00131 printf( " ARC4 test #%d: ", i + 1 ); 00132 00133 memcpy( buf, arc4_test_pt[i], 8 ); 00134 00135 arc4_setup( &ctx, (unsigned char *) arc4_test_key[i], 8 ); 00136 arc4_crypt( &ctx, buf, 8 ); 00137 00138 if( memcmp( buf, arc4_test_ct[i], 8 ) != 0 ) 00139 { 00140 if( verbose != 0 ) 00141 printf( "failed\n" ); 00142 00143 return( 1 ); 00144 } 00145 00146 if( verbose != 0 ) 00147 printf( "passed\n" ); 00148 } 00149 00150 if( verbose != 0 ) 00151 printf( "\n" ); 00152 00153 return( 0 ); 00154 } 00155 00156 #endif 00157 00158 #endif