Issues and challenges of classical cryptography in cloud computing

Cloud computing nowadays draws the attention of different users as it gives scalable and on-demand access to the resource. As a large number of users can access various cloud resources simultaneously, there will be a threat to every user present in the cloud environment. With the advent of cloud computing, security plays the primary concern. The cryptography plays a key role in maintaining the basic property such as confidentiality, integrity, and availability (CIA) of the information shared between different users. Traditional cryptography provides a secure exchange of information between the users. The data can be shared by using some key which will be used to encrypt the data at the sender side and to decrypt the data at the receiver side. In traditional cryptography, any operation to be performed in the cloud data need a decryption process that exposes confidential data in the cloud platform. These issues are addressed by the homomorphic encryption (HE) technique. This technique enables the cloud user to operate such as update and sort on the encrypted data itself. The partial HE (PHE) and full HE (FHE) are two available variants of HE to overcome the issues of the traditional cryptography system. This research is based on the different traditional cryptography and HE technique along with issues and challenges faced during the implementation. In this paper, the RSA algorithm is implemented as HE. Moreover, the authors try to reduce the time complexity of the RSA algorithm by implementing the homo-morphic RSA.