1 /* 2 * Copyright (C) 1999 AT&T Laboratories Cambridge. All Rights Reserved. 3 * 4 * This is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License as published by 6 * the Free Software Foundation; either version 2 of the License, or 7 * (at your option) any later version. 8 * 9 * This software is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, write to the Free Software 16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 17 * USA. 18 */ 19 20 /* 21 * vncauth.c - Functions for VNC password management and authentication. 22 */ 23 24 #ifdef __STRICT_ANSI__ 25 #define _BSD_SOURCE 26 #define _POSIX_SOURCE 27 #define _XOPEN_SOURCE 600 28 #endif 29 #ifdef LIBVNCSERVER_HAVE_SYS_TYPES_H 30 #include <sys/types.h> 31 #endif 32 #include <stdio.h> 33 #include <stdlib.h> 34 #include <unistd.h> 35 #include <rfb/rfbproto.h> 36 #include "d3des.h" 37 38 #include <string.h> 39 #include <math.h> 40 41 #ifdef LIBVNCSERVER_HAVE_SYS_STAT_H 42 #include <sys/stat.h> 43 #endif 44 45 #include <time.h> 46 47 #ifdef WIN32 48 #define srandom srand 49 #define random rand 50 #else 51 #include <sys/time.h> 52 #endif 53 54 55 /* libvncclient does not need this */ 56 #ifndef rfbEncryptBytes 57 58 /* 59 * We use a fixed key to store passwords, since we assume that our local 60 * file system is secure but nonetheless don't want to store passwords 61 * as plaintext. 62 */ 63 64 static unsigned char fixedkey[8] = {23,82,107,6,35,78,88,7}; 65 66 67 /* 68 * Encrypt a password and store it in a file. Returns 0 if successful, 69 * 1 if the file could not be written. 70 */ 71 72 int 73 rfbEncryptAndStorePasswd(char *passwd, char *fname) 74 { 75 FILE *fp; 76 unsigned int i; 77 unsigned char encryptedPasswd[8]; 78 79 if ((fp = fopen(fname,"w")) == NULL) return 1; 80 81 /* windows security sux */ 82 #ifndef WIN32 83 fchmod(fileno(fp), S_IRUSR|S_IWUSR); 84 #endif 85 86 /* pad password with nulls */ 87 88 for (i = 0; i < 8; i++) { 89 if (i < strlen(passwd)) { 90 encryptedPasswd[i] = passwd[i]; 91 } else { 92 encryptedPasswd[i] = 0; 93 } 94 } 95 96 /* Do encryption in-place - this way we overwrite our copy of the plaintext 97 password */ 98 99 rfbDesKey(fixedkey, EN0); 100 rfbDes(encryptedPasswd, encryptedPasswd); 101 102 for (i = 0; i < 8; i++) { 103 putc(encryptedPasswd[i], fp); 104 } 105 106 fclose(fp); 107 return 0; 108 } 109 110 111 /* 112 * Decrypt a password from a file. Returns a pointer to a newly allocated 113 * string containing the password or a null pointer if the password could 114 * not be retrieved for some reason. 115 */ 116 117 char * 118 rfbDecryptPasswdFromFile(char *fname) 119 { 120 FILE *fp; 121 int i, ch; 122 unsigned char *passwd = (unsigned char *)malloc(9); 123 124 if ((fp = fopen(fname,"r")) == NULL) { 125 free(passwd); 126 return NULL; 127 } 128 129 for (i = 0; i < 8; i++) { 130 ch = getc(fp); 131 if (ch == EOF) { 132 fclose(fp); 133 free(passwd); 134 return NULL; 135 } 136 passwd[i] = ch; 137 } 138 139 fclose(fp); 140 141 rfbDesKey(fixedkey, DE1); 142 rfbDes(passwd, passwd); 143 144 passwd[8] = 0; 145 146 return (char *)passwd; 147 } 148 149 150 /* 151 * Generate CHALLENGESIZE random bytes for use in challenge-response 152 * authentication. 153 */ 154 155 void 156 rfbRandomBytes(unsigned char *bytes) 157 { 158 int i; 159 static rfbBool s_srandom_called = FALSE; 160 161 if (!s_srandom_called) { 162 srandom((unsigned int)time(NULL) ^ (unsigned int)getpid()); 163 s_srandom_called = TRUE; 164 } 165 166 for (i = 0; i < CHALLENGESIZE; i++) { 167 bytes[i] = (unsigned char)(random() & 255); 168 } 169 } 170 171 #endif 172 173 /* 174 * Encrypt CHALLENGESIZE bytes in memory using a password. 175 */ 176 177 void 178 rfbEncryptBytes(unsigned char *bytes, char *passwd) 179 { 180 unsigned char key[8]; 181 unsigned int i; 182 183 /* key is simply password padded with nulls */ 184 185 for (i = 0; i < 8; i++) { 186 if (i < strlen(passwd)) { 187 key[i] = passwd[i]; 188 } else { 189 key[i] = 0; 190 } 191 } 192 193 rfbDesKey(key, EN0); 194 195 for (i = 0; i < CHALLENGESIZE; i += 8) { 196 rfbDes(bytes+i, bytes+i); 197 } 198 } 199 200 void 201 rfbEncryptBytes2(unsigned char *where, const int length, unsigned char *key) { 202 int i, j; 203 rfbDesKey(key, EN0); 204 for (i = 0; i< 8; i++) 205 where[i] ^= key[i]; 206 rfbDes(where, where); 207 for (i = 8; i < length; i += 8) { 208 for (j = 0; j < 8; j++) 209 where[i + j] ^= where[i + j - 8]; 210 rfbDes(where + i, where + i); 211 } 212 } 213
