Giuseppe De Falco

Digital signatures are a critical cryptographic primitive requiring quantum-safe solutions. One possibility are quantum digital signatures (QDS), which offer information-theoretic (IT) security without a trusted authority. However, even the most promising QDS proposals are largely limited to the tripartite scenario (one sender, two receivers) and are vulnerable to equivocation-based attacks that hinder transferability and non-repudiation. To overcome such limitations, we introduce an equivocation-resistant signature (ERS) protocol based on preshared keys and universal hashing that achieves IT security and scales to an arbitrary number of receivers. We benchmark the ERS protocol against state-of-the-art QDS schemes demonstrating orders-of-magnitude reductions in preshared key consumption and signature size. Our findings position our ERS protocol as a strong candidate for implementing IT-secure digital signatures in today’s quantum communication infrastructures.

Quantum key distribution (QKD) is an innovative technology allowing information-theoretically-secure key sharing among distant users relying only on fundamental rules of quantum physics, without assumptions about the computational power of the attacker. This work presents the architecture of the Rome QKD Metropolitan Area Network (QMAN), the different layers required to sustain such network, including the Key Management System developed by Leonardo and the interconnection with the Italian Quantum Backbone to intregrate this network in the EuroQCI program. The Rome QMAN is a quantum-safe hybrid network, made up of several nodes that are connected with both commercial fibre and a free-space link.