Counterfactual quantum key distribution protocols allow two sides to establish a common secret key using an insecure channel and authenticated public communication. As opposed to many other quantum key distribution protocols, part of the quantum state used to establish each bit never leaves the transmitting side, which hinders some attacks. We show how to adapt detector blinding attacks to this setting. In blinding attacks, gated avalanche photodiode detectors are disabled or forced to activate using bright light pulses. We present two attacks that use this ability to compromise the security of counterfactual quantum key distribution. The first is a general attack but technologically demanding. (The attacker must be able to reduce the channel loss by half.) The second attack could be deployed with easily accessible technology and works for implementations where single photon sources are approximated by attenuated coherent states. The attack is a combination of a photon number splitting attack and the first blinding attack which could be deployed with easily accessible technology. The proposed attacks show counterfactual quantum key distribution is vulnerable to detector blinding and that experimental implementations should include explicit countermeasures against it.

反事实量子密钥分发协议允许双方使用不安全的通道和经过身份验证的公共通信来建立公共密钥。与许多其他量子密钥分发协议相反，用于建立每个比特的部分量子状态永远不会离开传输端，这会阻碍一些攻击。我们展示了如何使检测器致盲攻击适应此设置。在致盲攻击中，门控雪崩光电二极管探测器被禁用或强制使用强光脉冲激活。我们提出了两种使用这种能力来破坏反事实量子密钥分发安全性的攻击。第一种是一般攻击，但技术要求很高。（攻击者必须能够将信道损失减少一半。）第二次攻击可以使用易于访问的技术进行部署，并且适用于通过衰减相干状态近似单光子源的实现。该攻击是光子数分裂攻击和第一次致盲攻击的组合，可以使用易于访问的技术进行部署。提议的攻击表明反事实量子密钥分发容易受到检测器致盲的影响，并且实验实施应包括针对它的明确对策。