Quantum Blockchain Relying on Quantum Secure Direct Communication Network

As a popular decentralized and distributed database exhibiting transparency and unforgeability, blockchain has received widespread attention. At the time of writing, its security hinges on classical cryptography, which maintains a high grade of security by exploiting the potentially excessive computational complexity of mathematical problems to be solved by state-of-the-art computers. However, as computational technology develops, this encryption philosophy is likely to be challenged and there is a risk of “store now and decrypt later” attacks. A compelling solution to this security threat is to intrinsically integrate blockchain with quantum technology. Against this background, we propose a quantum blockchain scheme relying on quantum secure direct communication (QSDC). Specifically, we conceive QSDC-based blockchain for identity verification, message encryption, and consensus. We also propose an optical network based realization of the proposed QSDC-aided blockchain using the present-day technology. Our simulations quantify the benefits of the scheme, especially in terms of its resource utilization. This work provides a new prospect for the intrinsic fusion of quantum information technology and blockchain technology, paving the way for its rapid commercialization.