Unconditionally Secure Quantum Signatures

TL;DR

This paper reviews unconditionally secure quantum signature schemes that offer information-theoretic security for classical messages, addressing the threat posed by quantum computers to traditional cryptographic signatures.

Contribution

It provides a comprehensive review of existing unconditionally secure quantum signature schemes, highlighting their importance in a post-quantum cryptographic landscape.

Findings

Quantum signatures remain secure against quantum attacks.

Existing schemes achieve unconditional security for classical message signing.

The review emphasizes the significance of quantum signatures for future cryptography.

Abstract

Signature schemes, proposed in 1976 by Diffie and Hellman, have become ubiquitous across modern communications. They allow for the exchange of messages from one sender to multiple recipients, with the guarantees that messages cannot be forged or tampered with and that messages also can be forwarded from one recipient to another without compromising their validity. Signatures are different from, but no less important than encryption, which ensures the privacy of a message. Commonly used signature protocols - signatures based on the Rivest-Adleman-Shamir (RSA) algorithm, the digital signature algorithm (DSA), and the elliptic curve digital signature algorithm (ECDSA) - are only computationally secure, similar to public key encryption methods. In fact, since these rely on the difficulty of finding discrete logarithms or factoring large primes, it is known that they will become completely insecure with the emergence of quantum computers. We may therefore see a shift towards signature protocols that will remain secure even in a post-quantum world. Ideally, such schemes would provide unconditional or information-theoretic security. In this paper, we aim to provide an accessible and comprehensive review of existing unconditionally secure signature schemes for signing classical messages, with a focus on unconditionally secure quantum signature schemes.