In cloud computing, the data owners outsource their data to public cloud server. For providing security, secure search over encrypted cloud has been used under single user model. But At times this has been supported by multiple owners to share benefits of cloud computing. To enable cloud server for secure search I have proposed a system with secret key generation and new data user authentication with multiple keyword search in multiple owner model for privacy preserving. To prevent the attackers from eavesdropping secret keys and pretending to be legal data users submitting searches, I propose a novel dynamic secret key generation protocol and a new data user authentication protocol. Secret Key generation is done by getting multiple keywords from the user.