Cryptology ePrint Archive: Report 2019/1456

ModFalcon: compact signatures based on module NTRU lattices

Chitchanok Chuengsatiansup and Thomas Prest and Damien Stehl� and Alexandre Wallet and Keita Xagawa

Abstract: Lattices lead to promising practical post-quantum digital signatures, combining asymptotic efficiency with strong theoretical security guarantees. However, tuning their parameters into practical instantiations is a delicate task. On the one hand, NIST round 2 candidates based on Lyubashevsky's design (such as dilithium and qtesla) allow several tradeoffs between security and efficiency, but at the expense of a large bandwidth consumption. On the other hand, the hash-and-sign falcon signature is much more compact and is still very efficient, but it allows only two security levels, with large compactness and security gaps between them. We introduce a new family of signature schemes based on the falcon design, which relies on module lattices. Our concrete instantiation enjoys the compactness and efficiency of falcon, and allows an intermediate security level. It leads to the most compact lattice-based signature achieving a quantum security above 128 bits.

Category / Keywords: public-key cryptography / public-key cryptography, Lattice-Based Cryptography, module lattices, signature scheme, public key encryption, NTRU

Date: received 17 Dec 2019, last revised 18 Dec 2019

Contact author: wallet alexandre at gmail com, damien stehle@gmail com, thomas prest@pqshield com, elisaemol@gmail com, xagawa@gmail com