I want to use asymmetric encryption of headers in RESTful requests to verify the identity of the system sending the request: i e System A encrypts it's name, timestamp, and the service name using it's public key in a request to System B. System B then uses the public key of System A to decrypt, proving the authenticity of the request. 1) Does php-mcrypt support this? 2) Has anyone benchmarked this type of operation?