POST-QUANTUM BLOCKCHAIN PROTOCOLS RESISTANT TO HYBRID CLASSICAL - QUANTUM ATTACKS

Abstract

With the emergence of quantum computing, the classical blockchain systems are under the immediate risk because quantum algorithms can undermine the common cryptographic algorithms. This paper explores post-quantum blockchain tools that are resistant to hybrid classical-quantum attacks, which are a combination of classical computation threats and quantum adversary models. Quantitative experimental method Six post-quantum cryptographic primitives, lattice-based (CRYSTALS-Dilithium, Falcon), hash-based (XMSS, SPHINCS+), and code-based (McEliece), were merged with three consensus mechanisms Proof-of-Work (PoW), Proof-of-Stake (PoS), and Practical Byzantine Fault Tolerance (PBFT). Simulations of hybrid attack vectors were done to measure attack success rates, key compromise probability, verification latency, throughput, energy consumption and consensus integrity values.Results have shown the lattice-based signatures are the most robust with the lowest key compromise risk, the hash-based and code-based schemes have equal trade-offs between performance and security. The PoS and PBFT consensus protocols are better than PoW in transaction throughput and energy efficiency, but they are not affected by hybrid attacks in terms of security or finality. The analysis indicates that there are imperative performance-security trade-offs, and modular, cryptographically agile blockchain designs are a must.The results will have practical implications to blockchain system designers to ensure the implementation of post-quantum secure blockchain decentralizations in finance, healthcare, and government applications. The study proves that post-quantum cryptography can be effectively integrated in blockchain infrastructures to protect the decentralized networks in the new quantum world.