I tried the examples of Java Security. However, operations that need a private key die with errors like java.security.UnrecoverableKeyException: DerInputStream.getLength(): lengthTag=10, too big.. Searches on the web yield no clue. Still figuring it out.

I started revising my submission, with William Yu (PDF) to the Philippine Journal of ICT and Microelectronics. This work was started months ago and deals with client-server HTTP content, but is relevant to the stuff I'm trying out with P2P.