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/*
* 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., 51 Franklin Street, Fifth Floor, 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);
}
}
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