Unified Butterfly for NTT in Post-Quantum Cryptography Algorithm CRYSTALs-Kyber

Quantum computing is a fast developing technology that puts the presently implemented cryptosystems at risk. National Institute of Standards and Technology announced CRSYTALs-Kyber as a standard after Post Quantum Cryptography competition. Kyber is a Lattice-based Cryptography algorithm that uses Number Theoretic transform technique to perform polynomial multiplication. To make NTT efficient, a compact and high-performance butterfly unit is required. In this work we have presented an FPGA based pipelined butterfly structure by incorporating a multiplier-free and low-complex Barrett reduction algorithm. Consequently, our design achieves an 18.2% increase in maximum operating frequency and 32.9% improvement in hardware efficiency.