Chat Application with PGP encryption

I am looking for a good web / app developer who is experienced in PGP encryption.
- I already build the chat application in PHP, I am looking for someone who can build PGP encryption in the already existing application
- Create an Android or iPhone application for it, not for publishing but for ourselves
- Need some advice and having some questions on this project how to do this securely
We need someone who also is willing to maintenance the project every month. So also long term work