Agile and versatile quantum communication: signatures and secrets

Abstract

Agile cryptography allows for a resource-efficient swap of a cryptographic core in case the security of an underlying classical cryptographic algorithm becomes compromised. Conversely, versatile cryptography allows the user to switch the cryptographic task without requiring any knowledge of its inner workings. In this paper, we suggest how these related principles can be applied to the field of quantum cryptography by explicitly demonstrating two quantum cryptographic protocols, quantum digital signatures (QDS) and quantum secret sharing (QSS), on the same hardware sender and receiver platform. Crucially, the protocols differ only in their classical post-processing. The system is also suitable for quantum key distribution (QKD) and is highly compatible with deployed telecommunication infrastructures, since it uses standard quadrature phase shift keying (QPSK) encoding and heterodyne detection. For the first time, QDS protocols are modified to allow for postselection at the receiver, enhancing protocol performance. The cryptographic primitives QDS and QSS are inherently multipartite and we prove that they are secure not only when a player internal to the task is dishonest, but also when (external) eavesdropping on the quantum channel is allowed. In our first proof-of-principle demonstration of an agile and versatile quantum communication system, the quantum states were distributed at GHz rates. This allows for a one-bit message to be securely signed using our QDS protocols in less than 0.05 ms over a 2 km fiber link and in less than 0.2~s over a 20 km fiber link. To our knowledge, this also marks the first demonstration of a continuous-variable direct QSS protocol.

11+6 pages. 8 figures. Accepted to Physical Review X

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Cited by in corpus (11)

• Experimental quantum secure network with digital signatures and encryption
• Advanced Architectures for High-Performance Quantum Networking
• Breaking Rate-Distance Limitation of Measurement-Device-Independent Quantum Secret Sharing
• One-Time Universal Hashing Quantum Digital Signatures without Perfect Keys
• Secure and practical multiparty quantum digital signatures
• Integrated quantum communication network and vibration sensing in optical fibers
• Quantum steering as a resource for secure tripartite Quantum State Sharing
• Continuous-variable quantum digital signatures that can withstand coherent attacks
• Asynchronous measurement-device-independent quantum digital signatures
• Efficient source-independent quantum conference key agreement
• Sharing classical secrets with continuous-variable entanglement: Composable security and network coding advantage