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-rw-r--r--vncauth.c161
1 files changed, 161 insertions, 0 deletions
diff --git a/vncauth.c b/vncauth.c
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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., 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 "rfb.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);
+ }
+}