Migration to Quantum Safe Blockchains: A Compact Architecture Using MPPK Key Encapsulation Mechanism and HPPK Digital Signatures

Abstract

The advent of quantum computing threatens the public-key cryptography that underlies modern blockchains, including ECDSA, Ed25519, and ECDH. Although NIST has standardized lattice-based schemes (ML-KEM and ML-DSA) as quantum-safe standards, their large key and signature sizes (several kilobytes each) pose scalability challenges for blockchains. We propose a quantum-safe blockchain architecture based entirely on multivariate polynomial cryptography, specifically the MPPK KEM key encapsulation mechanism and HPPK DS digital signature scheme. Using their linear configuration, MPPK KEM, and HPPK DS produce compact public keys (196-536 bytes) and signatures (144-272 bytes) – considerably smaller than ML-DSA’s 2–3 KB. We present a blockchain design that natively integrates these primitives. We analyze its security under classical and quantum adversarial models. We estimate transaction throughput and block capacity. Compared to lattice-based alternatives, our projections suggest that compact representations significantly improve transaction throughput and reduce on-chain storage. This work aims to contribute to ongoing quantum-safe standardization efforts, including those within ETSI, by demonstrating a concrete architectural pathway.