diff --git a/rfb/CSecurityVncAuth.cxx b/rfb/CSecurityVncAuth.cxx
new file mode 100644
index 0000000..3d6c87c
--- /dev/null
+++ b/rfb/CSecurityVncAuth.cxx
@@ -0,0 +1,63 @@
+/* Copyright (C) 2002-2003 RealVNC Ltd.  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 software; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
+ * USA.
+ */
+//
+// CSecurityVncAuth
+//
+
+#include <string.h>
+#include <stdio.h>
+#include <rfb/CConnection.h>
+#include <rfb/UserPasswdGetter.h>
+#include <rfb/vncAuth.h>
+#include <rfb/CSecurityVncAuth.h>
+#include <rfb/LogWriter.h>
+#include <rfb/util.h>
+
+using namespace rfb;
+
+static LogWriter vlog("VncAuth");
+
+CSecurityVncAuth::CSecurityVncAuth(UserPasswdGetter* upg_)
+  : upg(upg_)
+{
+}
+
+CSecurityVncAuth::~CSecurityVncAuth()
+{
+}
+
+bool CSecurityVncAuth::processMsg(CConnection* cc, bool* done)
+{
+  *done = false;
+  rdr::InStream* is = cc->getInStream();
+  rdr::OutStream* os = cc->getOutStream();
+
+  rdr::U8 challenge[vncAuthChallengeSize];
+  is->readBytes(challenge, vncAuthChallengeSize);
+  CharArray passwd;
+  if (!upg->getUserPasswd(0, &passwd.buf)) {
+    vlog.error("Getting password failed");
+    return false;
+  }
+  vncAuthEncryptChallenge(challenge, passwd.buf);
+  memset(passwd.buf, 0, strlen(passwd.buf));
+  os->writeBytes(challenge, vncAuthChallengeSize);
+  os->flush();
+  *done = true;
+  return true;
+}