MultiPrime cloud-RSA: a fast homomorphic encryption scheme for data confidentiality protection in clouds

Concerns over data confidentiality are amongst the main barriers limiting the widespread adoption of cloud solutions. Indeed, scientists have invented a new promising form of encryption, homomorphic encryption (HE), which can be considered as a powerful tool to get over these concerns. Since cloud environments are more vulnerable to attacks and since cloud consumers frequently access to cloud computing services using light-weight devices, the HE schemes must be promoted, in terms of security level and running time, to operate efficiently. In El Makkaoui et al. (2017), we boosted the normal RSA cryptosystem at security level, cloud-RSA. In this paper, we suggest a new fast variant of the Cloud-RSA scheme, MultiPime cloud-RSA, to accelerate its decryption process. The variant uses a modulus of the form n = Πk i=1 pi for k ≥ 2 and employs the Chinese remaindering to decrypt. Theoretical and simulation results show that the new variant offers a large decryption speed-up over the cloud-RSA scheme whilst maintaining a recommended security level.