基于恢复的擦除攻击对量子密钥分发系统
Recovery-Induced Erasure Attack on QKD Systems
AI总结：
本研究揭示了基于探测器恢复非线性的擦除攻击机制，展示了其在QKD系统中的安全漏洞及对传统防护措施的挑战。
摘要：
探测器死时间通常被视为量子密钥分发（QKD）安全分析中的固定参数。然而，在实践中，单光子雪崩光电二极管（SPAD）的有效恢复时间取决于入射计数率。在本工作中，我们证明了这种计数率依赖的恢复非线性性构成了一个独特的攻击原语。我们实验性地表征了在受控宽带加载下自由运行SPAD的死时间位移，并观察到当检测率进入高光子计数范围时，有效恢复时间显著增加。我们展示了由恢复引起的可用性减少可以建模为对抗性擦除信道，并推导出在加载下的信号检测概率的保守界限。与之前研究的探测器控制或效率不匹配攻击不同，所提出的机制不依赖于确定性屏蔽或时间辨别。相反，计数率依赖的恢复不对称性导致基底依赖的检测概率抑制（p_⊥ < p_∥），将不匹配引起的错误转换为损失。特别是，我们在主动基底BBM92系统中证明，这种效应降低了观测到的量子比特误码率（QBER）低于中止阈值，同时增加擦除概率。使用实验测量的探测器恢复数据，我们量化了在可实现这种隐蔽抑制的参数范围内。这些结果确立了计数率依赖的探测器恢复作为安全相关漏洞，并表明针对基于时间的效率不匹配设计的防护措施不直接针对恢复引起的擦除（RIE）攻击。我们的发现强调了需要将探测器恢复动态显式纳入实际QKD安全模型中。
英文摘要：
Detector dead time is typically treated as a fixed parameter in quantum key distribution (QKD) security analyses. In practice, however, the effective recovery time of single-photon avalanche photodiodes (SPADs) depends on the incident count rate. In this work, we demonstrate that this count-rate-dependent recovery nonlinearity constitutes a distinct attack primitive. We experimentally characterize the dead time shift of a free-running SPAD under controlled broadband loading and observe a substantial increase in effective recovery time as the detected rate rises into the high photon count regime. We show that recovery-induced availability reduction can be modeled as an adversarial erasure channel and derive a conservative bound on the signal detection probability under loading. Unlike previously studied detector-control or efficiency mismatch attacks, the proposed mechanism does not rely on deterministic blinding or timing discrimination. Instead, count-rate-dependent recovery asymmetry induces basis-dependent suppression of detection probabilities ($p_\perp<p_\parallel$), converting mismatch-induced errors into loss. Particularly, we show in active-basis BBM92 systems, this effect reduces the observed quantum bit error rate (QBER) below the abort threshold while increasing erasure probability. Using experimentally measured detector recovery data, we quantify the parameter regime in which such stealth suppression is achievable. These results establish count-rate-dependent detector recovery as a security-relevant vulnerability and show that countermeasures designed for timing-based efficiency mismatch do not directly address recovery-induced erasure (RIE) attack. Our findings underscore the need to incorporate detector recovery dynamics explicitly into practical QKD security models.
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