1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
|
/*
* Copyright (C) 1999 AT&T Laboratories Cambridge. All Rights Reserved.
*
* This is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
* USA.
*/
/*
* vncauth.c - Functions for VNC password management and authentication.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <vncauth.h>
#include <d3des.h>
/*
* We use a fixed key to store passwords, since we assume that our local
* file system is secure but nonetheless don't want to store passwords
* as plaintext.
*/
unsigned char fixedkey[8] = {23,82,107,6,35,78,88,7};
/*
* Encrypt a password and store it in a file. Returns 0 if successful,
* 1 if the file could not be written.
*/
int
vncEncryptAndStorePasswd(char *passwd, char *fname)
{
FILE *fp;
int i;
unsigned char encryptedPasswd[8];
if ((fp = fopen(fname,"w")) == NULL) return 1;
chmod(fname, S_IRUSR|S_IWUSR);
/* pad password with nulls */
for (i = 0; i < 8; i++) {
if (i < strlen(passwd)) {
encryptedPasswd[i] = passwd[i];
} else {
encryptedPasswd[i] = 0;
}
}
/* Do encryption in-place - this way we overwrite our copy of the plaintext
password */
deskey(fixedkey, EN0);
des(encryptedPasswd, encryptedPasswd);
for (i = 0; i < 8; i++) {
putc(encryptedPasswd[i], fp);
}
fclose(fp);
return 0;
}
/*
* Decrypt a password from a file. Returns a pointer to a newly allocated
* string containing the password or a null pointer if the password could
* not be retrieved for some reason.
*/
char *
vncDecryptPasswdFromFile(char *fname)
{
FILE *fp;
int i, ch;
unsigned char *passwd = (unsigned char *)malloc(9);
if ((fp = fopen(fname,"r")) == NULL) return NULL;
for (i = 0; i < 8; i++) {
ch = getc(fp);
if (ch == EOF) {
fclose(fp);
return NULL;
}
passwd[i] = ch;
}
fclose(fp);
deskey(fixedkey, DE1);
des(passwd, passwd);
passwd[8] = 0;
return (char *)passwd;
}
/*
* Generate CHALLENGESIZE random bytes for use in challenge-response
* authentication.
*/
void
vncRandomBytes(unsigned char *bytes)
{
int i;
unsigned int seed = (unsigned int) time(0);
srandom(seed);
for (i = 0; i < CHALLENGESIZE; i++) {
bytes[i] = (unsigned char)(random() & 255);
}
}
/*
* Encrypt CHALLENGESIZE bytes in memory using a password.
*/
void
vncEncryptBytes(unsigned char *bytes, char *passwd)
{
unsigned char key[8];
int i;
/* key is simply password padded with nulls */
for (i = 0; i < 8; i++) {
if (i < strlen(passwd)) {
key[i] = passwd[i];
} else {
key[i] = 0;
}
}
deskey(key, EN0);
for (i = 0; i < CHALLENGESIZE; i += 8) {
des(bytes+i, bytes+i);
}
}
|
