In this paper, we are proposing a new homomorphic encryption scheme which supports arithmetic over the real numbers. Our scheme is based on RLWE over a subring of a cyclotomic ring called conjugate-invariant ring. We show that this problem is no easier than a standard lattice problem over ideal lattices by the reduction of Peikert et al. (STOC 2017). Our scheme allows real numbers to be packed in a ciphertext without any waste of a plaintext space and consequently we can encrypt twice as many plaintext slots as the previous scheme while maintaining the same security level, storage, and computational costs.
Category / Keywords: ring learning with errors, homomorphic encryption, real number arithmetic Original Publication (with major differences): The 21st Annual International Conference on Information Security and Cryptology (ICISC 2018) Date: received 5 Oct 2018, last revised 28 Oct 2018 Contact author: yongsoosong at ucsd edu Available format(s): PDF | BibTeX Citation Note: Camera-ready version with minor revisions Version: 20181029:015054 (All versions of this report) Short URL: ia.cr/2018/952