Homomorphic additive lightweight block cipher scheme for securing IoT applications

Abstract

Recent emerging systems and applications may be able to process encrypted data to preserve user privacy. However, designing an efficient Homomorphic Encryption (HE) algorithm that can achieve good performance and robustness against attacks is primordial to better respond to real-time requirements and tiny devices. Unfortunately, existing homomorphic asymmetric schemes suffer from high computational complexity, storage, and communication overhead. On the other hand, homomorphic symmetric approaches suffer from a low level of security, and a big majority of them suffer from weaknesses in defending against known plain-text/cipher-text attacks. In this paper, an efficient symmetric homomorphic block cipher scheme is proposed to allow the performing of addition and average operations over cipher-texts. It defines a simple round function that should be iterated for nr≥2 iterations. Moreover, the dynamic key approach is used in this solution to reach a high level of security. To the best of our knowledge, it is a new symmetric additive homomorphic block cipher structure, and it defines three novel variants of addition round keys and two novel variants of the diffusion matrix. Furthermore, the proposed solution is analyzed in detail and evaluated in terms of security and performance levels. In comparison with well-known asymmetric additive HE schemes such as Paillier, BGN (Boneh, Goh, Nissim), BCP (Bresson, Catalano, Pointcheval), and ElGamal ECC (Elliptic Curve ), the obtained results prove that the proposed solution reaches a good balance between both performance and security levels. Therefore, the proposed solution can be applied on limited devices and especially for real-time scenarios that require the additive homomorphic property and the average calculation over cipher-texts.