diff --git a/common/rfb/CSecurity.h b/common/rfb/CSecurity.h
index 36da5c7..3fedc50 100644
--- a/common/rfb/CSecurity.h
+++ b/common/rfb/CSecurity.h
@@ -49,6 +49,7 @@
     virtual void destroy() { delete this; }
     virtual int getType() const = 0;
     virtual const char* description() const = 0;
+    virtual bool isSecure() const { return false; }
 
     /*
      * Use variable directly instead of dumb get/set methods.