Designing quantum-resilient blockchain architectures: A system-level framework for post-quantum cryptographic integration

Abstract

Since the introduction of Bitcoin in 2008, blockchain systems have predominantly relied on classical public-key cryptographic mechanisms, particularly ECDSA, for transaction authentication and establishing digital trust. The rapid advancement of quantum computing poses a long-term threat to blockchain systems that rely on classical public-key cryptography. Existing approaches primarily focus on replacing individual cryptographic primitives, with comparatively limited attention to their integration and system-level effects within blockchain architectures. To address this gap, this study proposes a Quantum-Secure Blockchain Architecture (QSBA) based on a modular Cryptographic Abstraction Layer (CAL) that supports cryptographic agility and the integration of classical and post-quantum primitives. A blockchain prototype was implemented to evaluate ECDSA, ML-DSA, and SLH-DSA for transaction authentication and ML-KEM for quantum-resistant key establishment. The evaluation combines cryptographic microbenchmarks with distributed network experiments involving up to 1000 nodes, 5000 transactions, and transaction arrival rates of up to 5000 transactions per second. The results show that ML-DSA provides a practical balance between post-quantum security and system performance, whereas SLH-DSA incurs substantially higher computational, storage, communication, and congestion overhead. ML-KEM demonstrates low latency in key generation, encapsulation, and decapsulation, supporting its suitability for post-quantum key establishment. To provide an integrated comparison, the proposed Quantum-Secure Blockchain Adaptability (QSBA) Score combines security suitability, computational performance, communication cost, distributed network behavior, and congestion resilience, using CRITIC (Criteria Importance Through Intercriteria Correlation)-derived, data-driven weights. ML-DSA achieves the highest QSBA Score of 0.9522, compared with 0.4993 for ECDSA and 0.5007 for SLH-DSA. The findings demonstrate that the selection of post-quantum primitives directly affects not only cryptographic performance but also blockchain communication and scalability, and that a system-level architectural approach is necessary for practical migration toward quantum-secure blockchain systems.