We present a new framework for defining information leakage in the setting of US equities trading, and construct methods for deriving trading schedules that stay within specified information leakage bounds. Our approach treats the stock market as an interactive protocol performed in the presence of an adversary, and draws inspiration from the related disciplines of differential privacy as well as quantitative information flow. We apply a linear programming solver using examples from historical trade and quote (TAQ) data for US equities and describe how this framework can inform actual algorithmic trading strategies.

We present a new generalising framework for conditional entropies, considering a limit construction over sequences of core-concave entropies, and prove that quasiconcave functions are the set of such limits. This generalising framework subsumes recently proposed frameworks for entropies in quantitative information flow, including entropies whose conditional form reflects the expected leakage and the leakage in the worst-case scenario. Thanks to the properties of the limits it is also shown that several important information theoretical properties can be proven for the generalised entropies satisfying the axioms.

This work presents an axiomatization for entropy based on an extension of concavity called core-concavity. We show that core-concavity characterizes the largest class of functions for which the data-processing inequality holds, under the assumption that conditional entropy is defined as a generalized average. Also, under the same assumption, we show that data-processing and “conditioning reduces entropy” properties are equivalent. We prove several properties of core-concave functions, including generalization of perfect secrecy and of Fano's inequality. We also show that definitions of conditional entropy based on worst-case can be retrieved as limit cases of generalized averages. A connection between statistical decision making and this axiomatic approach is also presented.

This work explores the problem of designing a channel that leaks the least amount of information while respecting a set of operational constraints. This paper focuses on deterministic channels and deterministic solutions. This setting is relevant because most programs and many channel design problems are naturally modelled by deterministic channels. Moreover, the setting is also relevant when considering an attacker who can observe many outputs of an arbitrary channel while the secret input stays the same: when the number of observations is arbitrarily large, the channel of minimal leakage is deterministic. The deterministic channel design problem has different solutions depending on which leakage measure is chosen. The problem is shown to be NP-hard in general. However, for a particular class of constraints, called k-complete hypergraph constraints, a greedy algorithm is shown to provide the optimal solution for a wide class of leakage measures.

This work introduces a new preorder over channels that is monotonic with Shannon's mutual information for all distributions over the input alphabet. Moreover, this monotonicity also holds when substituting mutual information for quantities relative to Arimoto-Rényi conditional entropies and guessing entropy. Several results connecting this new preorder with others from the literature are proven. This work also discusses an extension of Shannon ordering based on this new preorder, and establishes that channels ordered this way are also ordered with regards to both Shannon and min-capacity.

This paper concerns the analysis of information leaks in security systems. We address the problem of specifying and analyzing large systems in the (standard) channel model used in quantitative information flow (QIF). We propose several operators which match typical interactions between system components. We explore their algebraic properties with respect to the security-preserving refinement relation defined by Alvim et al. and McIver et al. We show how the algebra can be used to simplify large system specifications in order to facilitate the computation of information leakage bounds. We demonstrate our results on the specification and analysis of the Crowds Protocol. Finally, we use the algebra to justify a new algorithm to compute leakage bounds for this protocol.