By Yoann Pelet, Ittoop Vergheese Puthoor, Natarajan Venkatachalam, Sören Wengerowsky, Martin Lončarić, Sebastian Philipp Neumann, Bo Liu, Željko Samec, Mario Stipčević, Rupert Ursin, Erika Andersson, John G. Rarity, Djeylan Aktas, Siddarth Koduru Joshi.
Submitted to arXiv on 9 February 2022.
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. Our USS protocol 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.