Securing a quantum key distribution relay network using secret sharing

We present a simple new technique to secure quantum key distribution relay networks using secret sharing. Previous techniques have relied on creating distinct physical paths in order to create the shares. We show, however, how this can be achieved on a single physical path by creating distinct logical channels. The technique utilizes a random `drop-out' scheme to ensure that an attacker must compromise all of the relays on the channel in order to access the key.