New arbitrated quantum signature of classical messages against collective amplitude damping noise

Recently, Chong et al. [Opt. Comm. 284, (2011) 893–895] pointed out that a dishonest party in Yang and Wen's arbitrated quantum signature scheme [Opt. Comm. 283, (2010) 3198–3201] is able to reveal the other party's secret key without being detected by using the Trojan-horse attacks. However, the solution to avoid the attack still remains open. This work further points out that in Yang and Wen's scheme, the arbitrator is unable to arbitrate the dispute between two users. Consequently, a user can deny that he/she has signed or verified a signature without performing a Trojan-horse attack. A solution is proposed to solve this problem as well as the open problem mentioned earlier. ► We solve the Trojan-horse attacks pointed out by Chong et al. ► We solve the dispute problem between two users in Yang and Wen's scheme. ► Instead of quantum fingerprint, a cryptographic hash function is used.