一句话：提出用各组件泄漏量界定整体系统 g-leakage 的组合性边界，并推广 min-entropy 泄漏与并行信道结果。
定量信息流研究秘密与可观察量之间相关性导致的信息泄漏。其中 g-leakage 框架统一了多数信息论度量，但它通过最小化问题定义，对大规模系统计算代价较高。本文研究系统对应信道可分解为更简单信道的情形，通常发生在可观察量由多个组件构成时。主要贡献是推导整体系统（乘性）g-leakage 关于各组件 g-leakage 的上下界，并讨论 min-entropy 泄漏与并行信道等特例，从而推广和系统化已有结果。作者通过示例展示方法的有效性，并评估所给界的精度。
Information flow is the branch of security that studies the leakage of information due to correlation between secrets and observables. Since in general such correlation cannot be avoided completely, it is important to quantify the leakage. The most followed approaches to defining appropriate measures are those based on information theory. In particular, one of the most successful approaches is the recently proposed $g$-leakage framework, which encompasses most of the information-theoretic ones. A problem with $g$-leakage, however, is that it is defined in terms of a minimization problem, which, in the case of large systems, can be computationally rather heavy. In this paper we study the case in which the channel associated to the system can be decomposed into simpler channels, which typically happens when the observables consist of multiple components. Our main contribution is the derivation of bounds on the (multiplicative version of) $g$-leakage of the whole system in terms of the $g$-leakages of its components. We also consider the particular cases of min-entropy leakage and of parallel channels, generalizing and systematizing results from the literature. We demonstrate the effectiveness of our method and evaluate the precision of our bounds using examples.
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@article{Kawamoto0P16,
title = {On the Compositionality of Quantitative Information Flow},
author = {Yusuke Kawamoto and Konstantinos Chatzikokolakis and Catuscia Palamidessi},
journal = {Logical Methods in Computer Science},
volume = {Volume 13, Issue 3},
year = {2017},
doi = {10.23638/lmcs-13(3:11)2017}
}