International journal of network security

How Can Quasi-trusted Nodes Help to Securely Relay QKD Keys?

Quoc‐Cuong Le, Patrick Bellot

Published Nov 1, 2009• 1 citation

Abstract

We propose a new definition for quasi-trusted relays. Our quasi-trusted relays are defined as follows: (1) being honest enough to correctly follow a given multi-party finitetime communication protocol; (2) however, being under the monitoring of eavesdroppers. From the new definition, we first develop a simple 3-party quasi-trusted model called Quantum Quasi-Trusted Bridge (QQTB) model. In this model, the origin Alice and the destination Bob are assumed out of range of Quantum Key Distribution (QKD). Carol is a quasi-trusted relay that can share QKD links with Alice and Bob. We show that QQTB protocol allows Alice and Bob, in cooperation with Carol, to securely establish secret keys. The originality of QQTB protocol is that we do not need invoke entangled photon pairs. Then, we extend QQTB model to Quantum Quasi-Trusted Relay (QQTR) model that is capable of securely distributing secret keys over arbitrarily long distances. Although QQTB model requires entangled photon sources, the originality is that we do not invoke entanglement swapping and entanglement purification as in [5, 6, 15]. Keywords: Controlled-NOT (C-NOT) gate, quantum circuit, quantum Key Distribution (QKD), QKD relaying model, quasi-trusted model, unconditional security 1

DOI: 10.6633/ijns.200911.9(3).06

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