arXiv subjects

Christa Jenkins

Publications and source records attributed to Christa Jenkins.

3 recordsLinked to original sources

arXiv2026

Automatically Tightening Access Control Policies with Restricter

Robust access control is a cornerstone of secure software, systems, and networks. An access control mechanism is as effective as the policy it enforces. However, authoring effective policies that satisfy desired properties such as the principle of least privilege is a challenging task even for experienced administrators, as evidenced by many real instances of policy misconfiguration. In this paper, we set out to address this pain point by proposing Restricter, which automatically tightens each (permit) policy rule of a policy with respect to an access log, which captures some already exercised access requests and their corresponding access decisions (i.e., allow or deny). Restricter achieves policy tightening by reducing the number of access requests permitted by a policy rule without sacrificing the functionality of the underlying system it is regulating. We implement Restricter for Amazon's Cedar policy language and demonstrate its effectiveness through two realistic case studies.

cs.CR↗

arXiv2022

Proof Engineering with Predicate Transformer Semantics

We present a lightweight, open source Agda framework for manually verifying effectful programs using predicate transformer semantics. We represent the abstract syntax trees (AST) of effectful programs with a generalized algebraic datatype (GADT) AST, whose generality enables even complex operations to be primitive AST nodes. Users can then assign bespoke predicate transformers to such operations to aid the proof effort, for example by automatically decomposing proof obligations for branching code. Our framework codifies and generalizes a proof engineering methodology used by the authors to reason about a prototype implementation of LibraBFT, a Byzantine fault tolerant consensus protocol in which code executed by participants may have effects such as updating state and sending messages. Successful use of our framework in this context demonstrates its practical applicability.

cs.SE↗

arXiv2022

An approach to translating Haskell programs to Agda and reasoning about them

We are using the Agda programming language and proof assistant to formally verify the correctness of a Byzantine Fault Tolerant consensus implementation based on HotStuff / LibraBFT. The Agda implementation is a translation of our Haskell implementation based on LibraBFT. This short paper focuses on one aspect of this work. We have developed a library that enables the translated Agda implementation to closely mirror the Haskell code on which it is based. This makes it easier and more efficient to review the translation for accuracy, and to maintain the translated Agda code when the Haskell code changes, thereby reducing the risk of translation errors. We also explain how we capture the semantics of the syntactic features provided by our library, thus enabling formal reasoning about programs that use them; details of how we reason about the resulting Agda implementation will be presented in a future paper. The library that we present is independent of our particular verification project, and is available, open-source, for others to use and extend.

cs.LO↗