Unconditionally secure digital signatures implemented in an eight-user quantum network

Yoann Pelet, Ittoop Vergheese Puthoor, Natarajan Venkatachalam, Soren Wengerowsky, Martin Loncari, Sebastian Philipp Neumann, Bo Liu, Zeljko Samec, Mario Stipcevi, Rupert Ursin, Erika Andersson, John G Rarity, Djeylan Aktas and Siddarth Koduru Joshi

Abstract

The ability to know and verifiably demonstrate the origins of messages can often be as important as encrypting the message itself. Here we present an experimental demonstration of an unconditionally secure digital signature (USS) protocol implemented for the first time, to the best of our knowledge, on a fully connected quantum network without trusted nodes. We choose a USS protocol which is secure against forging, repudiation and messages are transferrable. We show the feasibility of unconditionally secure signatures using only bi-partite entangled states distributed throughout the network and experimentally evaluate the performance of the protocol in real world scenarios with varying message lengths.