Towards quantum-safe blockchain: Exploration of PQC and public-key recovery on embedded systems

Blockchain technology ensures accountability, transparency, and redundancy, but its reliance on public-key cryptography makes it vulnerable to quantum computing threats. This article addresses the urgent need for quantum-safe blockchain solutions by integrating post-quantum cryptography (PQC) into blockchain frameworks. Utilizing algorithms from the NIST PQC standardization process, it is aimed to fortify blockchain security and resilience, particularly for IoT and embedded systems. Despite the importance of PQC, its implementation in blockchain systems tailored for embedded environments remains underexplored. A quantum-secure blockchain architecture is proposed, evaluating various PQC primitives and optimizing transaction sizes through techniques such as public-key recovery for Falcon, achieving up to 17% reduction in transaction size. The analysis identifies Falcon-512 as the most suitable algorithm for quantum-secure blockchains in computer-based environments and XMSS as a viable but unsatisfactory stateful alternative. However, for embedded-based blockchains, Dilithium demonstrates a higher transactions-per-second (TPS) rate compared to Falcon, primarily due to Falcon's slower signing performance on ARM CPUs. This highlights the signing time as a critical limiting factor within embedded blockchains. Additionally, smart contract functionality is integrated, assessing the impact of PQC on smart contract authentication. The findings demonstrate the feasibility and practicality, paving the way for robust and future-proof IoT applications.