Abstract: Now a day’s public cloud storages have more benefits to provide service to users to manage their data. However for the rapidly increase of public cloud storage, the public cloud should solve the major issue of data confidentiality. That is sharing sensitive data through all the data must be strongly secured for unauthorized access. In order to provide security of sensitive data store in public clouds, a commonly used approach is to encrypt data before upload into public clouds. So that to provide confidentiality of stored public cloud data, the encryption mechanism should also able to support the access of confidential data. In this paper we are propose public key encryption schema for generation of secret key and encrypt the data using that key. The generation of secret key we are using public key power auditing protocol. Another concept is encryption and decryption of data using data encryption standard algorithm. By implementing those concepts we can improve efficiency and security of give shared data in a cloud.

Keywords: Cloud Computing, Cryptography, Security Access Control, Certificate less cryptography.