What's a good way to encrypt data using an asymmetric key, that's available to both java and ruby?

I have a customer that wants to encrypt some data in his database (not passwords; this needs actual encryption, not hashing). The application which will be doing the encrypting/writing is in Java, but the process which will DECRYPT it is behind a secure firewall开发者_运维百科, and is written in ruby.

The idea was to use a public/private key scheme; the java system would encrypt it with the public key, then the process on his local box would use the private key to decrypt it as needed.

I'm looking for any experience anyone has doing something like that; my main question is what sorts of libraries on java and ruby can interoperate with the same keys and data.

OpenPGP is supported by both Java and Ruby.

The nice thing about OpenPGP is that key management is all specified upfront, so you don't have to reinvent that particular wheel. (Encrypting and decrypting the data itself isn't hard. Managing the keys in a secure way is.)