Java and iPhone AES interoperability

I’ve been trying to get my head around cryptography on the iPhone so that I can create a native iPhone app (iPasskeep) that interoperates with my JPasskeep password keeper application. It has taken a while to get my head around CommonCrypto APIs - how to use them, how not to use them and their limitations. It then took a bit of fiddling to find the right incantations in Java to get an interoperable cryptographic transformation....