Collusion attack and counterattack on the quantum key agreement via non-maximally entangled cluster states
This addresses a security flaw in quantum cryptography protocols, which is incremental as it builds on prior work to enhance robustness against collusion.
The paper identifies a collusion attack vulnerability in a previous quantum key agreement protocol using non-maximally entangled cluster states, where dishonest participants can manipulate the final shared key undetected, and proposes an improved protocol to counter this attack.
Recently, Li et al. (Int J Theor Phys: DOI: 10.1007/s10773-020-04588-w, 2020) proposed a multiparty quantum key agreement protocol via non-maximally entangled cluster states. They claimed that the proposed protocol can help all the involved participants have equal influence on the final shared key. However, this study points out a loophole that makes Li et al.'s protocol suffer from a collusion attack, i.e. several dishonest participants can conspire to manipulate the final shared key without being detected by others. To avoid this loophole, an improvement is proposed here.