Harry Fuecks came across a need in his development work to bridge a gap between a PHP script and some Java work he'd done. He found the way that fit his situation the best - the encryption of the data on the PHP side via OpenSSL.
Needed a mechanism to be able to pass chunks of data securely from PHP to Java [...] One solution might be something "from scratch" involving mcrypt or PHP libraries like Crypt_RSA. [...] Another approach is GnuPG, either via the command line as discussed in this tutorial or via the GnuPG extension from PECL.
Option 3 is using OpenSSL and PHP's openssl_seal() function. SSL is normally used for encrypting networked communication between peers but that's not all it can do. [...] What's more - and perhaps the biggest win - it also allows us to re-use existing SSL certificates.
He uses the openssl_seal functionality on top of the EVP encrypted envelope on the certificate to handle the encrypt/decrypt of the data. Both the PHP code and Java code (and execution example) are included in the post.