19 research outputs found
Runtime Enforcement for Component-Based Systems
Runtime enforcement is an increasingly popular and effective dynamic
validation technique aiming to ensure the correct runtime behavior (w.r.t. a
formal specification) of systems using a so-called enforcement monitor. In this
paper we introduce runtime enforcement of specifications on component-based
systems (CBS) modeled in the BIP (Behavior, Interaction and Priority)
framework. BIP is a powerful and expressive component-based framework for
formal construction of heterogeneous systems. However, because of BIP
expressiveness, it remains difficult to enforce at design-time complex
behavioral properties.
First we propose a theoretical runtime enforcement framework for CBS where we
delineate a hierarchy of sets of enforceable properties (i.e., properties that
can be enforced) according to the number of observational steps a system is
allowed to deviate from the property (i.e., the notion of k-step
enforceability). To ensure the observational equivalence between the correct
executions of the initial system and the monitored system, we show that i) only
stutter-invariant properties should be enforced on CBS with our monitors, ii)
safety properties are 1-step enforceable. Given an abstract enforcement monitor
(as a finite-state machine) for some 1-step enforceable specification, we
formally instrument (at relevant locations) a given BIP system to integrate the
monitor. At runtime, the monitor observes and automatically avoids any error in
the behavior of the system w.r.t. the specification. Our approach is fully
implemented in an available tool that we used to i) avoid deadlock occurrences
on a dining philosophers benchmark, and ii) ensure the correct placement of
robots on a map.Comment: arXiv admin note: text overlap with arXiv:1109.5505 by other author
Gray-box monitoring of hyperproperties with an application to privacy
Runtime verification is a complementary approach to testing, model checking and other static verification techniques to verify software properties. Monitorability characterizes what can be verified (monitored) at run time. Different definitions of monitorability have been given both for trace properties and for hyperproperties (properties defined over sets of traces), but these definitions usually cover only some aspects of what is important when characterizing the notion of monitorability. The first contribution of this paper is a refinement of classic notions of monitorability both for trace properties and hyperproperties, taking into account, among other things, the computability of the monitor. A second contribution of our work is to show that black-box monitoring of HyperLTL (a logic for hyperproperties) is in general unfeasible, and to suggest a gray-box approach in which we combine static and runtime verification. The main idea is to call a static verifier as an oracle at run time allowing, in some cases, to give a final verdict for properties that are considered to be non-monitorable under a black-box approach. Our third contribution is the instantiation of this solution to a privacy property called distributed data minimization which cannot be verified using black-box runtime verification. We use an SMT-based static verifier as an oracle at run time. We have implemented our gray-box approach for monitoring data minimization into the proof-of-concept tool Minion. We describe the tool and apply it to a few case studies to show its feasibility
A modular notation for monitoring network systems
Design of next generation network systems with predictable behavior in all situations poses a significant challenge. Monitoring of events happening at different points in a distributed environment can detect the occurrence of events that indicates significant error conditions. We use Modular Timing Diagrams (MTD) as a specification language to describe these error conditions. MTD's are a component-oriented and compositional notation. We take advantage of these features of MTD and point out that, in many cases, global MTD specifications describing behaviors of several system component can be efficiently decomposed into a set of sub-specifications. Each of the sub-specifications describes a local monitor that is specific to the component on which the monitor is intended to run. We illustrate the compositional nature of MTD in describing several network monitoring conditions related to network security
Introduction to Runtime Verification
International audienceThe aim of this chapter is to act as a primer for those wanting to learn about Runtime Verification (RV). We start by providing an overview of the main specification languages used for RV. We then introduce the standard terminology necessary to describe the monitoring problem, covering the pragmatic issues of monitoring and instrumentation, and discussing extensively the monitorability problem
Various Notions of Opacity Verified and Enforced at Runtime
In this paper, we are interested in the validation of opacity where opacity means the impossibility for an attacker to retrieve the value of a secret in a system of interest. Roughly speaking, ensuring opacity provides confidentiality of a secret on the system that must not leak to an attacker. More specifically, we study how we can verify and enforce, at system runtime, several levels of opacity. Besides already considered notions of opacity, we also introduce a new one that provides a stronger level of confidentiality