Abstract To counter the threats posed by quantum computing attacks on blockchain systems, researchers have explored both post-quantum blockchain and quantum blockchain solutions. However, post-quantum blockchain typically relies on complex mathematical puzzles, which result in high computational complexity and, consequently, low operational efficiency. Conversely, quantum blockchain is entirely dependent on the quantum processing capabilities of its nodes, leading to significant consumption of quantum resources, high networking costs, and reduced practicality. To address these challenges, a blockchain framework based on a semi-quantum key distribution network, referred to as Semi-Quantum Blockchain (SQB), is proposed. SQB enables classical users to engage in transactions while ensuring the unconditional security provided by quantum cryptography, significantly reducing the costs associated with network formation. The security analysis demonstrates that SQB provides robust post-quantum security and significantly outperforms its peers in terms of quantum resource consumption and quantum communication efficiency, establishing it as a secure and efficient blockchain solution.
Abstract To counter the threats posed by quantum computing attacks on blockchain systems, researchers have explored both post-quantum blockchain and quantum blockchain solutions. However, post-quantum blockchain typically relies on complex mathematical puzzles, which result in high computational complexity and, consequently, low operational efficiency. Conversely, quantum blockchain is entirely dependent on the quantum processing capabilities of its nodes, leading to significant consumption of quantum resources, high networking costs, and reduced practicality. To address these challenges, a blockchain framework based on a semi-quantum key distribution network, referred to as Semi-Quantum Blockchain (SQB), is proposed. SQB enables classical users to engage in transactions while ensuring the unconditional security provided by quantum cryptography, significantly reducing the costs associated with network formation. The security analysis demonstrates that SQB provides robust post-quantum security and significantly outperforms its peers in terms of quantum resource consumption and quantum communication efficiency, establishing it as a secure and efficient blockchain solution.
The rapid development of quantum computing poses severe threats to traditional blockchain security mechanisms, while existing full-quantum blockchains face challenges regarding high hardware costs and limited scalability. To address these issues, this paper proposes a secure and practical semi-quantum blockchain system. Specifically, a Semi-Quantum Delegated Proof of Stake consensus mechanism is constructed by integrating an adapted semi-quantum voting protocol with the Borda count method and a malicious behavior penalty model. Furthermore, a lightweight transaction verification framework is designed based on semi-quantum key distribution, enabling classical users with limited quantum capabilities to participate securely. Theoretical analysis demonstrates that the system achieves unconditional security against quantum attacks while maintaining high throughput. These results indicate that the proposed asymmetric resource design significantly lowers hardware barriers compared to full-quantum schemes, effectively balancing security, practicality, and cost-effectiveness for post-quantum blockchain networks.
Amid breakthroughs in quantum computing, blockchain systems are experiencing a dual-track evolution characterized by threats from quantum attacks and empowerment through quantum technologies. Traditional blockchain architectures, which rely on public-private key cryptography and hash functions, face systemic risks to core functions such as transaction integrity verification and consensus security when exposed to quantum attacks. This paper systematically analyzes and compares two distinct technical approaches in the field of quantum-secure blockchain: post-quantum blockchain and quantum blockchain. The former enhances existing systems by integrating post-quantum cryptographic algorithms to resist quantum threats, aiming for a smooth transition from current architectures. The latter reconstructs distributed ledger technology based on quantum information properties such as entanglement, forming novel architectures involving quantum key distribution networks, quantum digital signatures, and quantum consensus algorithms. The feasibility and development potential of these approaches are examined in application scenarios such as industrial IoT. A comparative analysis is conducted on their technical constraints and implementation challenges from the perspectives of transaction efficiency, security model validation, and standardization maturity. This lays a foundation for future empirical research. Finally, potential development paths are discussed, and targeted research directions such as diversified migration and dynamic hybrid strategies are proposed to guide further studies.
The emergence of quantum computing poses a significant threat to the security of blockchain protocols, primarily due to the vulnerability of current cryptographic algorithms to quantum attacks. This vulnerability jeopardizes the integrity of data and assets stored on blockchain networks, which currently hold hundreds of billions of dollars in cryptocurrencies and other digital assets. To mitigate this risk, various proposals and solutions have been presented in the literature. However, most existing proposals are either theoretical, rely on large quantum key distribution (QKD) networks, or advocate for the development of new quantumresistant blockchain networks from scratch. Despite the understanding of the quantum threat and potential solutions, practical implementations are scarce. A recent survey paper addresses this gap by proposing an end-to-end framework for achieving postquantum resistance in existing blockchain networks. The framework, outlined in the survey, is compatible with Ethereum-based networks and offers practical solutions for key generation, secure communication between nodes, and transaction verification. Notably, the framework utilizes quantum entropy for key generation, and post-quantum TLS connections, and introduces post-quantum signatures in transactions. Additionally, it incorporates on-chain verification mechanisms using Solidity smart contracts and modified EVM Opcode. This chapter represents a significant contribution to the field by providing a comprehensive overview of existing solutions and proposing a practical framework for enhancing blockchain security against quantum threats.
Quantum computing's development poses a significant threat to the cryptographic security of current blockchain technologies, potentially undermining the integrity of digital transactions. Quantum computers can break the complex mathematical problems that algorithms like RSA and ECC rely on, which could lead to vulnerabilities such as double-spending and fraud. To address these risks, the blockchain community is exploring quantum-resistant protocols that employ post-quantum cryptographic algorithms, which are designed to withstand quantum computing attacks. Quantum-secure blockchain protocols integrate quantum key distribution (QKD) and post-quantum cryptography (PQC) to enhance security. QKD uses quantum mechanics principles to secure communication channels, ensuring that any attempt to intercept the key introduces detectable anomalies. PQC involves algorithms like lattice-based, hash-based, or multivariate polynomial-based algorithms that are believed to be secure against quantum attacks. These protocols aim to maintain the confidentiality, integrity, and security of data transmitted over the blockchain, ensuring the longevity and reliability of blockchain systems in the face of evolving computational advancements. A quantum-secure blockchain scheme (QSB) utilizes a consensus mechanism, QPoA, and IQS. The QPoA is leveraged for block generation while the IQS is deployed in transaction verification1. Furthermore, the integration of quantum computing with blockchain can address current limitations, such as slow transaction speeds and lack of scalability, by optimizing calculations and enabling smarter, more sophisticated smart contracts. The development and implementation of quantum-resistant blockchains are essential for future-proofing digital transactions and maintaining trust in decentralized systems
Blockchain technology has recently attracted significant attention from academia and industry alike due to its potential to address security challenges in data transfer. The cryptographic mechanisms underlying traditional Blockchain systems rely on mathematical problems that are computationally difficult for classical computers to solve efficiently. However, recent advances in quantum computing, notably through Shor’s and Grover’s algorithms, present significant risks to the security of these traditional cryptographic systems, potentially exposing them to quantum-based cyberattacks. These risks underscore the need to strengthen Blockchain’s resilience against quantum-enabled threats. Two distinct approaches have emerged in response. The first approach focuses on post-quantum Blockchains, which aim to adopt cryptographic algorithms resistant to quantum attacks. The second approach, referred to as quantum Blockchain, explores the use of quantum computing principles to fundamentally redesign Blockchain mechanisms and algorithms. This paper provides a comprehensive analysis of both post-quantum and quantum Blockchain approaches, addressing open questions, challenges, and research trends in these fields.
This paper examines the growing threat that quantum computing presents to blockchain security. Core blockchain cryptographic frameworks, specifically the Elliptic Curve Digital Signature Algorithm and the Secure Hash Algorithm 256, are vulnerable to quantum algorithms. Both the Shor algorithm and the Grover algorithm are capable of breaking the Elliptic Curve Digital Signature Algorithm, enabling attackers to calculate private keys from public keys, while the Grover algorithm can also compromise hash-based systems that depend on brute-force methods, such as Proof-of-Work. On-chain analysis indicates that billions of dollars’ worth of crypto-assets are held in addresses susceptible to these quantum attacks. A proposed countermeasure is migration to Post-Quantum Cryptography, which incorporates quantum-resistant algorithms, such as CRYSTALS-Dilithium and Falcon. However, this migration introduces a trilemma among network security, decentralization, and performance. Post-Quantum Cryptography algorithms significantly increase transaction sizes and computational costs, which pose economic and technical challenges for large blockchain networks. The paper further discusses how the timeline for quantum advancements will be shaped by geopolitical competition, and how the catch-the-crop, decrypt-later strategy puts current data at risk from future quantum decryption. It emphasizes that active migration to Post-Quantum Cryptography is urgent, calling on stakeholders to prioritize system audits, transition to cryptographically flexible infrastructures, promote research into quantum-resistant solutions, and establish governance frameworks that enable prompt and decentralized upgrades.