  State-of-the-art Quantum Key Distribution (QKD) is based on the uncertainty
principle of qubits on quantum measurements and is theoretically proven to be
unconditionally secure. Over the past three decades, QKD has been explored with
single photons as the information carrier. More recently, attention has shifted
towards using weak coherent laser pulses as the information carrier. In this
paper, we propose a novel quantum key distribution mechanism over a pure
optical channel using randomized Glauber states. The proposed mechanism closely
resembles a quantum mechanical implementation of the public key envelope idea.
For the proposed solution, we explore physical countermeasures to provide path
authentication and to avoid man-in-the-middle attacks. Other attack vectors can
also be effectively mitigated by leveraging the QPKE, the uncertainty principle
and the DPSK modulation technique.
