Early security proofs of the keys in quantum cryptography systems were based on the assumption that the transmitting and receiving stations were completely isolated from the outside world—the eavesdropper. However, this condition cannot be implemented in practice, since quantum cryptography systems are open systems, in the sense that an eavesdropper can have indirect access, for example, through a fiber communication channel to critical equipment elements (phase modulators, intensity modulators, etc) using active sensing of the state of these elements—Trojan-horse attacks. A new Trojan-horse attack based on joint unambiguous measurements of reflected probing states from an intensity modulator and information states in a quantum communication channel is proposed. Estimates of attack parameters for a number of quantum key distribution protocols are given, when an attack leads to compromise of keys.

中文翻译：

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量子密码学中的明确测量和特洛伊木马攻击

量子密码系统中密钥的早期安全性证明是基于这样的假设，即发送站和接收站与外界（窃听者）完全隔离。但是，由于量子密码系统是开放系统，因此从某种意义上说，窃听者可以通过光纤通信通道间接访问关键设备元件（相位调制器，强度调制器等），因此该条件实际上无法实现。使用主动感知这些元素的状态（特洛伊木马攻击）。提出了一种新的特洛伊木马攻击，该攻击基于对强度调制器的反射探测状态和量子通信信道中信息状态的联合明确测量。