Blockchain technology affords data integrity protection and building trust mechanisms in transactions for distributed networks, and, therefore, is seen as a promising revolutionary information technology. At the same time, the ongoing breakthrough in quantum computation technology contributes toward large-scale quantum computers, which might attack classic cryptography, seriously threatening the classic cryptography security currently employed in the blockchain. As a better alternative, a quantum blockchain has high expectations of being immune to quantum computing attacks perpetrated by quantum adversaries. Although several works have been presented, the problems of impracticality and inefficiency in quantum blockchain systems remain prominent and need to be addressed. First, this paper develops a quantum-secure blockchain (QSB) scheme by introducing a consensus mechanism—quantum proof of authority (QPoA) and an identity-based quantum signature (IQS)—wherein QPoA is used for new block generation and IQS is used for transaction signing and verification. Second, QPoA is developed by adopting a quantum voting protocol to achieve secure and efficient decentralization for the blockchain system, and a quantum random number generator (QRNG) is deployed for randomized leader node election to protect the blockchain system from centralized attacks like distributed denial of service (DDoS). Compared to previous work, our scheme is more practical and efficient without sacrificing security, greatly contributing to better addressing the challenges in the quantum era. Extensive security analysis demonstrates that our scheme provides better protection against quantum computing attacks than classic blockchains. Overall, our scheme presents a feasible solution for blockchain systems against quantum computing attacks through a quantum strategy, contributing toward quantum-secured blockchain in the quantum era.

With the rise of IoT technology, remote medical services have gained increasing attention. These services became particularly popular during the COVID-19 pandemic due to their convenience, privacy, and ability to transcend geographical boundaries. In remote medical networks, identity authentication protocols are a crucial component, playing a vital role in ensuring that healthcare providers can operate in a secure and efficient environment. However, some existing identity authentication protocols in remote medical environments are vulnerable to various security threats, such as privileged insider attacks, session key security issues, unauthorized data access, and failure to meet both three-factor security and anonymity. These threats can compromise patient privacy and the integrity of healthcare systems.Therefore, the development of a secure and efficient identity authentication protocol for remote medical services is of utmost importance. To address this need, we propose a Physically Unclonable Function-based identity authentication scheme for telemedicine. In our scheme, we use symmetric encryption and Elliptic Curve Cryptography to encrypt critical information, ensuring a high level of security. We leverage PUF technology to associate devices with users, creating a “device fingerprint” for enhanced authentication. Furthermore, we have provided security proofs for our scheme using the Random Oracle model and the ProVerif protocol analysis tool. Through comprehensive security analysis, we demonstrate that the proposed scheme can resist most known attacks and meets anonymity, forward/backward security, and three-factor security. Lastly, we compared our scheme with existing protocols in terms of computational overhead, storage overhead, and communication overhead using a unified performance benchmark. The results indicate that, while there is no advantage in communication overhead, our scheme reduces computational overhead by approximately 50.71% and storage overhead by 16.32%.

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.