In this work, we have proposed an approach for providing very high security to the cloud system. Our proposed method comprises of three phases namely authentication phase, cloud data centre selection phase and user related service agreement phase. For the purpose of accessing data from the cloud server, we will need a secure authentication key. In the authentication phase, the user authentication is verified and gets the key then encrypts the file using blowfish algorithm. Before encryption the input data is divided into column-wisely with the help of pattern matching approach. In the approach, the encryption and decryption processes are carried out by employing the blowfish algorithm. We can optimally select the cloud data centre to store the data; here the position is optimally selected with the help of bat algorithm. In the final phase, the user service agreement is verified. The implementation will be done by cloud sim simulator.