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
rfbEncryptAndStorePasswd(char * passwd,char * fname)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 *
rfbDecryptPasswdFromFile(char * fname)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
rfbRandomBytes(unsigned char * bytes)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
rfbEncryptBytes(unsigned char * bytes,char * passwd)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
rfbEncryptBytes2(unsigned char * where,const int length,unsigned char * key)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