325 research outputs found
Modalities, Cohesion, and Information Flow
It is informally understood that the purpose of modal type constructors in
programming calculi is to control the flow of information between types. In
order to lend rigorous support to this idea, we study the category of
classified sets, a variant of a denotational semantics for information flow
proposed by Abadi et al. We use classified sets to prove multiple
noninterference theorems for modalities of a monadic and comonadic flavour. The
common machinery behind our theorems stems from the the fact that classified
sets are a (weak) model of Lawvere's theory of axiomatic cohesion. In the
process, we show how cohesion can be used for reasoning about multi-modal
settings. This leads to the conclusion that cohesion is a particularly useful
setting for the study of both information flow, but also modalities in type
theory and programming languages at large
A Temporal Logic for Hyperproperties
Hyperproperties, as introduced by Clarkson and Schneider, characterize the
correctness of a computer program as a condition on its set of computation
paths. Standard temporal logics can only refer to a single path at a time, and
therefore cannot express many hyperproperties of interest, including
noninterference and other important properties in security and coding theory.
In this paper, we investigate an extension of temporal logic with explicit path
variables. We show that the quantification over paths naturally subsumes other
extensions of temporal logic with operators for information flow and knowledge.
The model checking problem for temporal logic with path quantification is
decidable. For alternation depth 1, the complexity is PSPACE in the length of
the formula and NLOGSPACE in the size of the system, as for linear-time
temporal logic
Combining behavioural types with security analysis
Today's software systems are highly distributed and interconnected, and they
increasingly rely on communication to achieve their goals; due to their
societal importance, security and trustworthiness are crucial aspects for the
correctness of these systems. Behavioural types, which extend data types by
describing also the structured behaviour of programs, are a widely studied
approach to the enforcement of correctness properties in communicating systems.
This paper offers a unified overview of proposals based on behavioural types
which are aimed at the analysis of security properties
Hidden-Markov Program Algebra with iteration
We use Hidden Markov Models to motivate a quantitative compositional
semantics for noninterference-based security with iteration, including a
refinement- or "implements" relation that compares two programs with respect to
their information leakage; and we propose a program algebra for source-level
reasoning about such programs, in particular as a means of establishing that an
"implementation" program leaks no more than its "specification" program.
This joins two themes: we extend our earlier work, having iteration but only
qualitative, by making it quantitative; and we extend our earlier quantitative
work by including iteration. We advocate stepwise refinement and
source-level program algebra, both as conceptual reasoning tools and as targets
for automated assistance. A selection of algebraic laws is given to support
this view in the case of quantitative noninterference; and it is demonstrated
on a simple iterated password-guessing attack
03411 Abstracts Collection -- Language Based Security
From October 5th to 10th 2003,the Dagstuhl Seminar 03411
``Language Based security\u27\u27 was held
in the International Conference and Research Center (IBFI), Schloss Dagstuhl.
During the seminar, several participants presented their current
research, and ongoing work and open problems were discussed. Abstracts of
the presentations given during the seminar are put together in this paper
Logical Relations for Session-Typed Concurrency
Program equivalence is the fulcrum for reasoning about and proving properties
of programs. For noninterference, for example, program equivalence up to the
secrecy level of an observer is shown. A powerful enabler for such proofs are
logical relations. Logical relations only recently were adopted for session
types -- but exclusively for terminating languages. This paper scales logical
relations to general recursive session types. It develops a logical relation
for progress-sensitive noninterference (PSNI) for intuitionistic linear logic
session types (ILLST), tackling the challenges non-termination and concurrency
pose, and shows that logical equivalence is sound and complete with regard to
closure of weak bisimilarity under parallel composition, using a
biorthogonality argument. A distinguishing feature of the logical relation is
its stratification with an observation index (as opposed to a step or unfolding
index), a crucial shift to make the logical relation closed under parallel
composition in a concurrent setting. To demonstrate practicality of the logical
relation, the paper develops an information flow control (IFC) refinement type
system for ILLST, with support of secrecy-polymorphic processes, and shows that
well-typed programs are self-related by the logical relation and thus enjoy
PSNI. The refinement type system has been implemented in a type checker,
featuring local security theories to support secrecy-polymorphic processes.Comment: arXiv admin note: text overlap with arXiv:2208.1374
Noninterference Analysis of Reversible Systems: An Approach Based on Branching Bisimilarity
The theory of noninterference supports the analysis and the execution of
secure computations in multi-level security systems. Classical
equivalence-based approaches to noninterference mainly rely on weak
bisimulation semantics. We show that this approach is not sufficient to
identify potential covert channels in the presence of reversible computations.
As illustrated via a database management system example, the activation of
backward computations may trigger information flows that are not observable
when proceeding in the standard forward direction. To capture the effects of
back and forth computations, it is necessary to switch to a more expressive
semantics that, in an interleaving framework, has been proven to be branching
bisimilarity in a previous work by De Nicola, Montanari, and Vaandrager. In
this paper we investigate a taxonomy of noninterference properties based on
branching bisimilarity along with their preservation and compositionality
features, then we compare it with the classical hierarchy based on weak
bisimilarity
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