# Asynchronous Quantum-Resistant Blockchain for Secure Intelligence Sharing
## 1 Introduction  
Sharing threat intelligence data is essential in a contemporary, interconnected digital landscape where cyber threats evolve rapidly and pose significant risks to organizations and individuals alike. By pooling together data on emerging threats, attack techniques, and vulnerabilities, organizations can gain a comprehensive understanding of the threat landscape and identify potential risks early on. According to a Ponemon Institute report [1], high-performing companies are often willing to share intelligence than other companies. The report highlights the collaborative benefits of shared threat intelligence in enhancing cybersecurity posture and reducing risk. Moreover, government agencies, such as the Cybersecurity and Infrastructure Security Agency (CISA) in the United States, actively promote threat intelligence sharing among public and private sector organizations. Through programs like the Automated Indicator Sharing (AIS) [2], participating organizations can exchange actionable threat indicators in real time, enabling them to strengthen their cyber defenses and respond to emerging threats more effectively. However, when the source of intelligence information is unclear, it may lead to problems with quality and content. Research by [PERSON] et al. [3] also pointed out that the current intelligence information focuses on quantity rather than the quality of information. Furthermore, organizations may engage in the sharing community with opportunistic motives, such as minimal contribution or exploiting the intelligence provided by others, leading to free-riding behavior. Therefore, the tamper-proof information sharing process and contributing members are important issues for information sharing. Blockchain as a tamper-proof and decentralized storage technology has gained lots of attention recently. Along with well-known cryptocurrencies, non-fungible tokens (NFTs) have also made frequent appearances in various reports and news. For instance, in December 2021, an NFT artwork created by the artist [PERSON] was sold for a staggering $91.8 million [4]. This event brought blockchain applications into the global spotlight, with widespread adoption in not only the financial sector but also in enterprises [5], healthcare [6], and the legal system [7]. Additionally, countries worldwide are actively seeking international patents related to blockchain [8], with China and the United States leading the way, having filed nearly 55,000 patents as of June 2021. This highlights the international significance of blockchain as an indispensable, decentralized data storage technology. Nevertheless, the emergence of quantum computing poses a threat to most public key algorithms used today, as established by major international companies such as Microsoft and Google. These research have demonstrated the potential impact of quantum computing on current cryptographic techniques [9; 10]. Therefore, it has become imperative to replace national critical infrastructure with post-quantum algorithms, prompting the National Institute of Standards and Technology (NIST) to initiate a competition for post-quantum cryptography standards. Recognizing the escalating risks posed by advancements in quantum computing, the National Institute of Standards and Technology (NIST) has undertaken a comprehensive initiative to standardize post-quantum cryptographic (PQC) algorithms. As of August 2024, NIST has finalized its initial set of encryption standards designed to withstand quantum computer-based cyberattacks. The primary standard for general encryption is based on the CRYSTALS-KYBER algorithm, now referred to as ML-KEM (Module-Lattice-Based Key-Encapsulation Mechanism). For digital signatures, NIST has standardized two algorithms: ML-DSA (Module-Lattice-Based Digital Signature Algorithm), derived from the CRYSTALS-Dilithium algorithm, and SLH-DSA (Stateless Hash-Based Digital Signature Algorithm), based on the SPHINCS+ algorithm.