Authority-based user authentication in quantum key distribution

Abstract

We propose secure protocols for user authenticated quantum key distribution. We argue that the use of a trusted authority becomes inevitable in a realistic environment as that of multi-user key distribution. Here, we specifically look at one protocol that use nonorthogonal bases with two-qubit entanglement. As the trusted authority being the only one knowing the correlations of this entanglement he/she can protect an unauthorized user from getting the right key.