Encrypt Ruby/Rails source code

Question

Is there a way to encrypt Rails code so that the user could not mess with the written code?
What I actually want to do is to distribute a LAN-Only REST Web Server application, which will be installed on customer's computer. I do not want them to copy my work and distribute it without me knowing it.
I've already read this one:
Ruby on Rails source code security / obfuscation
And people have suggested to use http://rubyencoder.com/
Is there any open-source alternative to this one? Does it work at all? Is it possible to package the Rails app with JRuby in a jar file or something? Any suggestions on blocking the third-party access is appreciated.