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
64static 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
72int
73rfbEncryptAndStorePasswd(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
117char *
118rfbDecryptPasswdFromFile(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
155void
156rfbRandomBytes(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
177void
178rfbEncryptBytes(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
200void
201rfbEncryptBytes2(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