AI 中文总结
针对抗损耗的$f$-BB84量子位置验证方案，证明攻击者需满足近线性量子门下界，确立了该方案在有界量子门假设下的安全性，核心为损耗BB84纠缠游戏的紧解析权衡。
AI 中文摘要
量子位置验证是一项密码学任务，其中验证者试图确定证明者在空间中的位置。近期实验已实现一类被广泛研究的位置验证方案，即$f$-BB84场景，但它们在存在实际损耗和不完美态制备下的安全性仍未被完全理解。我们针对该方案的任何攻击给出了新的下界，特别证明了攻击者需满足近线性的量子门下界，即使允许攻击者声明高达50%的传输损耗、裁判制备的挑战不完美，且协议中使用的量子消息可任意慢。我们的结果适用于近期及即将开展的$f$-BB84实验实现，尤其在攻击者受限于有界量子门假设的情况下确立了其安全性。核心要素是损耗BB84纠缠一夫多体游戏的紧解析权衡，该权衡无需攻击者输出一致，替代了此前仅数值层面的观测结果。
英文摘要
Quantum position-verification is a cryptographic task wherein a verifier attempts to establish the location in space of a prover. Recent experiments have implemented a well-studied class of position-verification schemes, known as the $f$-BB84 scenario, but their security under realistic loss and imperfect state preparation remains incompletely understood. We give a new lower bound on any attack on this scheme, in particular proving nearly-linear quantum gate lower bounds on the attacker, even when allowing the attacker to declare a transmission loss of up to $50\%$, allowing for the challenges prepared by the referee to be imperfect, and allowing the quantum messages used in the protocol to be arbitrarily slow. Our results are applicable to recent and upcoming experimental implementations of $f$-BB84, and in particular establish their security under a bounded quantum gate assumption on the attacker. The key ingredient is a tight analytic tradeoff for a lossy BB84 monogamy-of-entanglement game, valid without requiring the attackers' outputs to agree, which replaces observations previously made numerically.
Comments23 pages, 4 figures
