Applying Logarithm and Russian Multiplication Protocols to Improve Paillier’s Cryptosystem

Abstract

Cloud computing provides on-demand access to a diverse set of remote IT services. It offers a number of advantages over traditional computing methods. These advantages include pay-as-you-go pricing, increased agility and on-demand scalabil-ity. It also reduces costs due to increased efficiency and better business continuity. The most significant barrier preventing many businesses from moving to the cloud is the security of crucial data maintained by the cloud provider. The cloud server must have complete access to the data to respond to a client request. That implies the decryption key must be sent to the cloud by the client, which may compromise the confidentiality of data stored in the cloud. One way to allow the cloud to use encrypted data without knowing or decrypting it is homomorphic encryption. In this paper, we focus on improving the Paillier cryptosystem, first by using two protocols that allow the cloud to perform the multiplication of encrypted data and then comparing the two protocols in terms of key size and time.