Recently, Lang put forward for the first time a quantum gate-based quantum private comparison (QPC) protocol (Int J Theor Phys, 59(2020)833) which uses the quantum controlled-not gates to implement comparison instead of classical exclusive-or computations. It was claimed that this quantum gate-based QPC protocol is secure against both the outside attack and the participant attack. However, in this paper, it is pointed out that this protocol cannot resist a special measurement attack from the third party (TP) and the disturbance attack from an outside attacker. The corresponding improvements are further suggested to remedy these security loopholes.

中文翻译：

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基于量子门的量子私有比较的密码分析与改进

最近，Lang 首次提出了一种基于量子门的量子私有比较（QPC）协议（Int J Theor Phys, 59(2020)833），该协议使用量子控制的非门来实现比较，而不是经典的异或计算。据称，这种基于量子门的 QPC 协议对于外部攻击和参与者攻击都是安全的。然而，本文指出该协议无法抵抗来自第三方（TP）的特殊测量攻击和来自外部攻击者的干扰攻击。进一步建议进行相应的改进以弥补这些安全漏洞。