"Distributed phase reference schemes are a new class of protocols for Quantum Key Distribution, in which the quantum signals have overall phase-relationships to each other. This is expected to protect against some loss-related attacks. However, proving the full security of these schemes is a new challenge for theorists, as one can no longer identify individual signals (such as qubits in BB84, for instance), and so the security proof techniques do not apply directly.
In this talk I will present two such protocols (the Differential Phase Shift and the Coherent One Way protocols). Their ""unconditionnal security"" has not been proven yet, but I will present some specific attacks on these schemes, which give us upper bounds for the security, as well as a ""feeling"" on how these schemes should perform."