Efficient integer encoding for homomorphic encryption via ring isomorphisms

Abstract

Homomorphic encryption allows computation on encrypted data at the cost of a significant loss in efficiency. In this paper we propose a powerful integer encoding for homomorphic encryption. The proposed encoding offers more efficient and convenient homomorphic computations on integers compared to previously used methods. This is possible by making the message space of the encryption scheme isomorphic to an integer quotient ring. The encoding can be used across various latticebased homomorphic encryption schemes such as NTRU and various ring- LWE based schemes. We analyse the efficiency of our proposed encoding, which shows a significant gain compared to a naive integer encoding for a ring-LWE based scheme.