U-EPS: An Ultra-small and Efficient Post-quantum Signature Scheme

Lamport and Winternitz signature schemes are well known one-time quantum resistant digital signature schemes. Along this line, several new one-time signature schemes are proposed. However, their private key and signature sizes are of O(n(2)) for k < n-bit security. Considering the applications in Internet of Things (IoT) and blockchains, O(n(2)) size is notably high. In this paper, we introduce a new one-time post-quantum signature scheme called U-EPS which achieve k = 112-bit security with private key size 2n and signature sizes 3n bits (for n = 256), respectively. Our scheme only requires two calls of hash function and a single call of encryption/decryption algorithm for signature generation and verification procedures. We provide a concrete instantiation and implementation of U-EPS using SPIX-256 which is a NIST Lightweight Cryptographic Project Round 2 candidate. Finally, we give the comparison results with existing schemes.