EncryptableBehaviour is a project mainly written in PHP, it's free.
Store data encrypted in the db transparently
Written for 1.3
Encrypts data in a db. Encrypted fields should be binary type.
Usage: var $actsAs = array( 'Encryptable' => array( 'fields' => array( 'EncryptedModel' => array( 'encrypted_field' ) ) ) );
TODO - Recursing through associated models should be better.