Quantum Digital Signatures

TL;DR

This paper introduces a quantum digital signature scheme that leverages quantum physics principles to achieve unconditionally secure message authentication, with implications for quantum public key distribution and cryptography.

Contribution

It presents a novel quantum digital signature protocol that ensures unconditional security, integrating quantum public keys into classical cryptographic frameworks.

Findings

Scheme achieves unconditionally secure signatures

Quantum public keys are limited in circulation for security

Protocol models quantum public key distribution

Abstract

We present a quantum digital signature scheme whose security is based on fundamental principles of quantum physics. It allows a sender (Alice) to sign a message in such a way that the signature can be validated by a number of different people, and all will agree either that the message came from Alice or that it has been tampered with. To accomplish this task, each recipient of the message must have a copy of Alice's "public key," which is a set of quantum states whose exact identity is known only to Alice. Quantum public keys are more difficult to deal with than classical public keys: for instance, only a limited number of copies can be in circulation, or the scheme becomes insecure. However, in exchange for this price, we achieve unconditionally secure digital signatures. Sending an m-bit message uses up O(m) quantum bits for each recipient of the public key. We briefly discuss how to securely distribute quantum public keys, and show the signature scheme is absolutely secure using one method of key distribution. The protocol provides a model for importing the ideas of classical public key cryptography into the quantum world.