Exploiting Data Redundancy in CKKS Encoding for High-Speed Homomorphic Encryption

This paper presents an efficient encoding method for CKKS Homomorphic Encryption (HE) that exploits data redundancy to make the conversion of complex/real numbers to plaintext polynomials efficient without sacrificing security or accuracy.While the proposed method is amenable to customized hardware implementation, it is specifically designed to be embedded within HE software libraries such as Microsoft SEAL to provide a fast software implementation of CKKS encoding.Experimental evaluations show that the proposed approach results in up to 1.4× and 1.5× speed-ups for encoding complex and real numbers, respectively, compared to the SEAL library CKKS encoding for polynomial modulus degrees from 4096 to 32768.