Design superseded (notice added 2026-07-06): the QBER/visibility-based coherence scoring in this v1 design is withdrawn — channel-quality metrics correlate with fiber distance and are optimizable by short co-located links, so they do not constitute unforgeable proof of infrastructure investment (see the paper's own §8.3(4)). A redesigned mechanism (secure-key-length lottery) is in preparation and will be linked here. The ETSI 014 integration architecture and the general hardware-attestation problem statement remain valid; the v1 scoring function and its incentive analysis should not be cited as current design. We present Proof of Coherence (PoC), a novel blockchain consensus mechanism that leverages real-time quantum key distribution (QKD) hardware metrics as the basis for leader election and block validation. Unlike post-quantum cryptographic approaches that defend against quantum computers using classical hardware, PoC requires nodes to operate QKD equipment and uses channel quality metrics—particularly quantum coherence time, quantum bit error rate (QBER), and visibility—as unforgeable proof of physical infrastructure investment.
Design superseded (notice added 2026-07-06): the QBER/visibility-based coherence scoring in this v1 design is withdrawn — channel-quality metrics correlate with fiber distance and are optimizable by short co-located links, so they do not constitute unforgeable proof of infrastructure investment (see the paper's own §8.3(4)). A redesigned mechanism (secure-key-length lottery) is in preparation and will be linked here. The ETSI 014 integration architecture and the general hardware-attestation problem statement remain valid; the v1 scoring function and its incentive analysis should not be cited as current design. We present Proof of Coherence (PoC), a novel blockchain consensus mechanism that leverages real-time quantum key distribution (QKD) hardware metrics as the basis for leader election and block validation. Unlike post-quantum cryptographic approaches that defend against quantum computers using classical hardware, PoC requires nodes to operate QKD equipment and uses channel quality metrics—particularly quantum coherence time, quantum bit error rate (QBER), and visibility—as unforgeable proof of physical infrastructure investment.
Ensuring data confidentiality and integrity in critical infrastructures has become increasingly challenging due to the rise of quantum computing and the limitations of classical cryptographic systems. This paper presents Q-ChainX, a hybrid system, which combines the concepts of Quantum Key Distribution (QKD) with a Post-Quantum Cryptographic (PQC) enabled blockchain, to build ultra secure, tamper resistant and resilient in the future data infrastructures. The suggested architecture consists of two communication layers, namely quantum and classical communication to transmit data and secure keys, respectively, and uses entanglement-based E91 QKD to generate symmetric keys. The cryptographic core supports NTRU and CRYSTALS-Dilithium algorithms to substitute the standard RSA and ECC, which are resistant to quantum attacks. The consensus is obtained by the modified Proof-of-Authority mechanism supported by quantum randomness in the form of QRNGs, to allow a secure and fair election of validators. The key generation rates of a simulated Hyperledger environment simulated in Hyperledger-SimulaQron were found to be over 3800 bps, transaction finality time was found to be 408 ms on 15 nodes, and the consensus success rate was found to be 99.5. The hybrid quantum-PQC mode recorded 99.95 % data integrity and zero key compromise, ranked above the classical set up in all significant security parameters. These findings confirm the practicability of applying Q-ChainX in practice to the smart grids, defense communications, and medical data platforms. The further upgrading will be oriented on the optimization of quantum hardware, expansion of satellite-based QKD, and interoperability with multi-chain ecosystems. Q-ChainX is also a quantum leap to quantum resilient distributed systems, and it guarantees privacy, trust, and sustainability in the era of quantum computing.
This paper proposes a novel blockchain consensus mechanism termed "Distributed Proof-of-Work with Quantum Key Distribution" (DPW-QKD). The core idea is to leverage quantum key distribution (QKD) to replace computationally intensive hash functions in traditional Proof-of-Work (PoW) systems, thereby significantly reducing energy consumption. The system operates by nodes generating cryptographic keys through QKD, which are then utilized in a distributed QKD protocol to verify transaction validity. This approach eliminates the need for miners to solve complex cryptographic puzzles, creating a more energy-efficient and potentially more secure consensus model. The paper outlines the architecture, key components, and operational principles of the DPW-QKD system, highlighting its advantages and potential challenges. Mathematical formulations are presented to illustrate the key processes and security considerations within the system. The research aims to explore a viable pathway towards a sustainable and robust blockchain technology, driven by the inherent security of quantum mechanics.
Integrating Internet of Things (IoT) networks with blockchain technology has introduced transformative potential for secure, decentralized applications. However, with expanding IoT networks and the rapid advancements in quantum computing, which can break the classical encryption mechanism employed in these networks, securing validator communications in blockchain consensus mechanisms becomes increasingly challenging. This study presents PureQuantum, a novel quantum-enhanced framework that integrates quantum key distribution (QKD) into a proof-of-authority and association (PoA 2 ) consensus mechanism. Our experimental evaluation demonstrates that PureQuantum achieves a key generation time of approximately 2.315 s (BB84) and an average error rate of 0.2493, thereby ensuring robust resistance to classical and quantum computational threats. Exploring the architecture, design, and performance of PureQuantum, this concept highlights its ability to balance scalability, energy efficiency, and quantum-resilient security. By integrating QKD into validator communication protocols, PureQuantum provides a future-proof framework capable of supporting the demands of IoT-enabled decentralized systems.
Quantum computing is an evolution of classical computing, capable of solving problems that are competitive enough to break the existing cryptographic primitives upon which current blockchain systems are based. Popular schemes like RSA, ECDSA, and SHA-256 can be compromised by quantum algorithms (Shor's and Grover's), raising questions about the security and trustworthiness of blockchain-based applications in finance, healthcare, and supply chains. Many current approaches focus on isolated aspects of the blockchain, such as cryptographic primitives or key exchange, without a comprehensive strategy that can guarantee end-to-end security in the face of a quantum threat. Finally, traditional consensus mechanisms such as Proof-of-Work and Proof-of-Stake are vulnerable to Sybil attacks, centralization, and leader-selection bias. When the adversary has access to a quantum computer, these issues become significantly worse. In this paper, we present QuantumShield-BC, a modular blockchain framework incorporating post-quantum cryptographic signatures, quantum key distribution (QKD), and a novel Quantum Byzantine Fault Tolerance (Q-BFT) consensus mechanism driven by quantum random number generation (QRNG) to address these challenges. QKD: The system supports tamper-proof key exchange, quantum-resilient consensus among validator nodes, and secure transaction signing. Experimental evaluation demonstrates that QuantumShield-BC achieves low consensus latency and high throughput, while providing perfect security against simulated attacks from Shor's and Grover's algorithms. The proposed framework eradicates the Sybil attack effectiveness up to 0%, eliminates replay and MITM vulnerabilities, and achieves an average throughput of over 7,000 transactions per second with 100 validators, orders of magnitude better than classical blockchain systems. The importance of each quantum part to the system's robustness is also demonstrated using an ablation study. With its unique ability to provide a post-quantum framework for high-assurance, general-purpose, scalable, and interoperable blockchain networks resistant to quantum-inspired attacks or quantum retrieval, QuantumShield-BC is practical for deployment in critical infrastructure and digital trust ecosystems where performance and a future-proof foundation are essential.
The emergence of quantum computing threatens classical cryptographic systems, prompting the development of quantum-resistant solutions. At the same time, blockchain technology has been recognized for its capacity to provide immutable, auditable records, but existing implementations largely rely on cryptographic primitives vulnerable to quantum attacks. In genomic research, the integrity, provenance, and confidentiality of sequence data are paramount: any undetected tampering can compromise downstream analyses, misguide clinical decisions, or violate patient trust. This paper introduces Quantum Blockchain for Verifiable Genome Mapping Systems (QB-VGMS), a hybrid architecture that melds quantum key distribution (QKD)–based secure channels with a permissioned, quantum-resistant blockchain to enable end-to-end verifiability of genome mapping operations. In our design, genome fragments are hashed using SHA-3 and stored on-chain alongside metadata, while bulk sequence data resides in encrypted off-chain repositories. The consensus protocol employs QKD to distribute fresh symmetric keys among validator nodes, coupled with a quantum-random leader election to resist both classical and quantum adversaries. We describe a prototype implementation using simulated QKD links and Hyperledger Fabric extended for quantum security. Performance evaluation on human chromosome 21 datasets (48 MB total, partitioned into 1 MB fragments) demonstrates sub-one-second average transaction latency and throughput scaling up to 15 fragments per second under concurrent load. Security assessments confirm tamper-evident auditing and confidentiality against unauthorized decryption attempts. We conclude by discussing practical deployment challenges—such as QKD hardware integration, consensus scalability, and regulatory compliance—and outline pathways for integrating advanced privacy-enhancing technologies.
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