Information-Theoretic Secure Key Sharing for Wide-Area Mobile Applications

With the rapid growth of handheld devices in the Internet of Things (loT) networks, mobile applications have become ubiquitous in everyday life. As technology is developed, so also do the risks and threats associated with it - especially in the forthcoming quantum era. Existing loT networks, however, lack a quantum-resistant secret key sharing scheme to meet confidential message transmission demands in wide-area mobile applications. To address this issue, this article proposes a new scheme, channel reciprocity (CR), based on quantum key distribution (QKD) CR-QKD, accomplishes the secret key sharing goal by combining emerging QKD and CR-based key generation (CRKG) techniques. Exploiting the laws of quantum physics and wireless channels properties, the proposed scheme is able to ensure key secrecy, even against computationally unbounded adversaries. Elaborated for a single-user case, the basic mechanism is extended into a multi-user case - by redesigning a multi-user edge forwarding strategy. In addition, to make CR-QKD more practical, some enhancement strategies are studied to reduce the time delay, and to improve the secret key generation rate in a secure manner. A CR-QKD prototype is demonstrated in a metropolitan area network, where secret keys are shared between two remote loT devices roughly fifteen kilometers apart. Experimental results have verified CR-QKD allows a secret key rate of 424 bits per second, with a retransmission rate of 2.1 percent.