Completely Secure Alternative Quantum Key Distribution with High Bit Rates Over Long Distances

At present, quantum key distribution (QKD) can generate completely secure keys over a small distance (~5 km) with a poor bit rate (~10 bits/s) using untrusted devices in practical settings. In addition, QKD requires the support of a classical authentication scheme to ensure security. Here, we present the idea of an alternative QKD that can generate completely secure keys over a large distance (~100 km) with an estimated high bit rate (~10⁶ bits/s) using untrusted devices in practical settings. We also point out that entangled states can be used for quantum communication and that messages can be entangled.