Abstract
Quantum digital signatures (QDSs) allow the sending of messages from one sender to multiple recipients, with the guarantee that messages cannot be forged or tampered with. Additionally, messages cannot be repudiated--if one recipient accepts a message, she is guaranteed that others will accept the same message as well. While messaging with these types of security guarantees are routinely performed in the modern digital world, current technologies only offer security under computational assumptions. QDSs, on the other hand, offer security guaranteed by quantum mechanics. All thus far proposed variants of QDSs require long-term, high quality quantum memory, making them unfeasible in the foreseeable future. Here, we present a QDS scheme where no quantum memory is required, which also needs just linear optics. This makes QDSs feasible with current technology.
Highlights
Quantum digital signatures (QDSs) allow the sending of messages from one sender to multiple recipients, with the guarantee that messages cannot be forged or tampered with
The key advantage of QDSs is in the information-theoretic security, similar to quantum key distribution (QKD)
In [2], a QDS scheme based on coherent states was proposed, where comparison can be performed using linear optics
Summary
Quantum digital signatures (QDSs) allow the sending of messages from one sender to multiple recipients, with the guarantee that messages cannot be forged or tampered with. We present a QDS scheme where no quantum memory is required, which needs just linear optics This makes QDSs feasible with current technology. For QDSs to compete with classical protocols we may have to store millions of qubits (or qumodes) coherently, for long times This is a serious shortcoming given that state-of-the-art quantum memories cannot achieve coherence times longer than minutes [4]. QDSs without quantum memory.—QDS protocols have a distribution stage, where quantum signatures are sent to all future recipients, and a messaging stage, where classical messages are sent and verified. The quantum signatures are converted to classical information through quantum measurements, eliminating the
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