Cryptanalysis of the arbitrated quantum signature protocols

TL;DR

This paper critically analyzes existing arbitrated quantum signature protocols, revealing vulnerabilities to forgery and disavowal attacks, and discusses potential improvements and future research directions.

Contribution

It provides a detailed cryptanalysis of current AQS protocols, exposing security flaws and proposing avenues for enhancing their robustness.

Findings

Receiver Bob can forge signatures under known message attack.

Bob can achieve universal forgery on classical messages.

Sender Alice can disavow her signatures through simple attacks.

Abstract

As a new model for signing quantum message, arbitrated quantum signature (AQS) has recently received a lot of attention. In this paper we study the cryptanalysis of previous AQS protocols from the aspects of forgery and disavowal. We show that in these protocols the receiver Bob can realize existential forgery of the sender's signature under known message attack. Bob can even achieve universal forgery when the protocols are used to sign a classical message. Furthermore, the sender Alice can successfully disavow any of her signatures by simple attack. The attack strategies are described in detail and some discussions about the potential improvements of the protocols are given. Finally we also present several interesting topics in future study on AQS protocols.