发表机构
The Hong Kong University of Science and Technology (Guangzhou)（香港科技大学（广州））
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
针对现有基于状态观测的不透明性无法捕捉部分场景需求的问题，提出存在性不透明性（EO）概念，其更具表达力，还开发了对应验证方法，为不透明性保护问题可行性提供新准则。
AI 中文摘要
不透明性是离散事件系统（DES）中用于保密性的基本系统属性。经典不透明性通常在基于事件的观测下定义，要求任何秘密系统行为对于外部入侵者而言，仍与某些非秘密行为无法区分。然而，在路径规划或不透明性保护任务等诸多应用中，入侵者观测的是系统状态而非事件。此外，系统展现出可被用于执行不透明性保护任务的秘密行为往往就足够了，但这类系统属性无法被现有基于状态观测的不透明性概念完全捕捉。受此局限性启发，我们提出了一种对现有基于状态观测的不透明性的放松概念，称为存在性不透明性（EO），它仅要求存在秘密行为（而非所有秘密行为），这些秘密行为在入侵者的状态观测下与非秘密行为无法区分。我们证明，EO概念比现有基于状态观测的不透明性概念更具表达力。此外，我们开发了一类EO属性及其对应的验证方法，可用于分析离散事件系统中的存在性不透明性，并为确定不透明性保护问题的可行性提供了新准则。
英文摘要
Opacity is a fundamental system property for confidentiality in discrete-event systems (DES). Classical opacity is typically defined under event-based observations, requiring that any secret system behavior remains indistinguishable from some non-secret behavior to an external intruder. However, in many applications such as path planning or opacity-preserving tasks, the intruder observes system states rather than events. Moreover, it often suffices that the system exhibits secret behaviors that can be exploited for opacity-preserving task execution, but such a system property cannot be fully captured by existing notions of state-observation-based opacity. Motivated by this limitation, we propose a relaxed notion of existing state-observation-based opacity, called existential opacity (EO), which only requires the existence of secret behaviors (instead of all secret behaviors) that are indistinguishable from a non-secret behavior under the state observations of the intruder. We show that the notion of EO is more expressive than existing state-observation-based opacity notions. In addition, a class of EO properties together with their corresponding verification approaches are developed, enabling the analysis of existential opacity in discrete-event systems and providing a new criterion for determining the feasibility of opacity-preserving problems.
