使用BouncyCastle轻量级API的OpenPGP加密

I have to encrypt some content using a 256 bit AES-CBC key. The encryption protocol to be followed is OpenPGP. Since the key size is 256 bit and the public/private keys will also be of 4096 bit I will have to use the lightweight APIs. I have found several questions that show how to encrypt using a 256 bit AES-CBC key but I cannot figure out how to integrate that with PGP.I have to encrypt some content using a 256 bit