Do not rely on it or use it for security purposes. Do not override methods unless you have good, specific reasons. All methods should be final unless you have a good reason. Java's new security features that allow for signing code can allow applets more access to the end user's resources and system. You should sign code only if absolutely necessary.
Unsigned code is much less likely to be able do damage.
Resources and References University of Washington Department of Computer Science and Engineering, The Kimera Java Security Project . Princeton University Department of Computer Science, Secure Internet Programming . Java Developer's Guide , Sams.net Publishing, 1996. Tricks of the Java Programming Gurus , Sams.net publishing, 1996. EarthWeb is a division of INT Media Group, Incorporated.