论文标题
通过强匡威进行量子隐私放大的沟通的完全不安全感
Total insecurity of communication via strong converse for quantum privacy amplification
论文作者
论文摘要
量子隐私放大是量子密码学的核心任务。给定共享的随机性，最初与窃听者持有的量子系统相关，其目标是提取与后者脱钩的均匀随机性。已知该任务的最佳速率可以满足强横向属性，我们在相应的强匡威指数上提供了下限。在强匡威区域，协议的最终状态与所需的脱钩状态的最终状态在渐近极限下以指数级的快速收敛到其最大值。我们表明，这必然导致完全不安全的通信，即确定窃听者可以确定地推断出任何发送的消息，而当给出了非常有限的额外信息时。实际上，我们证明，在强大的匡威区域，窃听器与可实现的区域相比，在正确推断发送消息方面具有指数优势。此外，我们建立以下技术结果，这是我们的证明至关重要的，并且具有独立感兴趣：平滑最大相关熵的平滑参数满足了强大的相反特性。
Quantum privacy amplification is a central task in quantum cryptography. Given shared randomness, which is initially correlated with a quantum system held by an eavesdropper, the goal is to extract uniform randomness which is decoupled from the latter. The optimal rate for this task is known to satisfy the strong converse property and we provide a lower bound on the corresponding strong converse exponent. In the strong converse region, the distance of the final state of the protocol from the desired decoupled state converges exponentially fast to its maximal value, in the asymptotic limit. We show that this necessarily leads to totally insecure communication by establishing that the eavesdropper can infer any sent messages with certainty, when given very limited extra information. In fact, we prove that in the strong converse region, the eavesdropper has an exponential advantage in inferring the sent message correctly, compared to the achievability region. Additionally we establish the following technical result, which is central to our proofs, and is of independent interest: the smoothing parameter for the smoothed max-relative entropy satisfies the strong converse property.
