Faster AVX2 optimized NTT multiplication for Ring-LWE lattice cryptography
Gregor Seiler
Cryptology ePrint Archive, 2018, Report 2018/039.
Constant-time polynomial multiplication is one of the most time-consuming operations in many lattice-based cryptographic constructions. For schemes based on the hardness of Ring-LWE in power-of-two cyclotomic fields with completely splitting primes, the AVX2 optimized implementation of the Number-Theoretic Transform (NTT) from the NewHope key-exchange scheme is the state of the art for fast multiplication. It uses floating point vector instructions. We show that by using a modification of the Montgomery reduction algorithm that enables a fast approach with integer instructions, we can improve on the polynomial multiplication speeds of NewHope and Kyber by a factor of $4.2$ and $6.3$ on Skylake, respectively.
BibTeX Citation
@misc{Seiler18,
author = {Gregor Seiler},
title = {Faster AVX2 optimized NTT multiplication for Ring-LWE lattice cryptography},
series = {Cryptology ePrint Archive},
year = 2018,
note = {Report 2018/039},
}