Dado <mario_zupan@inet.hr> scribbled on the stall wall:

Realistically, the only way to do this in JAVA is to require network access
everytime the application is run and to get a cookie from a network
authentication server.  Note that NOTHING pisses users like me off more
than REQUIRING network access to use a program though.

First, a general comment: there is no guaranteed way of protecting your
application from being pirated. The only consolation that you will have is
that it must be really good to be stolen.

Now, you can try and make it more _difficult_ (but certainly not
_impossible_) to steal your product by requiring a license key to unlock the
product's capabilities; such key can be generated by you on the basis of
some information unique to the user (like MAC, although it is not 100%
unique either... but sufficiently unique for the licensing purposes). Java
bytecode can be easily reverse-engineered, so to further protect your
product you will probably want to obfuscate it. Search Google for java
bytecode obfuscation.

Finally, instead of trying to block access to your source code, you can make
it open-sourced and make it available to the users under some sort of
license (e.g. look at the licensing practices of MySQL).

Alex Molochnikov
Gestalt Corporation
www.gestalt.com