Runtime enforcement of regular timed properties by suppressing and delaying events

Abstract

Runtime enforcement is a verification/validation technique aiming at correcting possibly incorrect executions of a system of interest. In this paper, we consider enforcement monitoring for systems where the physical time elapsing between actions matters. Executions are thus modelled as timed words (i.e., sequences of actions with dates). We consider runtime enforcement for timed specifications modelled as timed automata. Our enforcement mechanisms have the power of both delaying events to match timing constraints, and suppressing events when no delaying is appropriate, thus possibly allowing for longer executions. To ease their design and their correctness-proof, enforcement mechanisms are described at several levels: enforcement functions that specify the input-output behaviour in terms of transformations of timed words, constraints that should be satisfied by such functions, enforcement monitors that describe the operational behaviour of enforcement functions, and enforcement algorithms that describe the implementation of enforcement monitors. The feasibility of enforcement monitoring for timed properties is validated by prototyping the synthesis of enforcement monitors from timed automata.

Testing Real-Time Systems With Runtime Enforcement

“…The work reported in [5] on the runtime enforcement of timed properties is also close from our offline phase. Our offline technique assumes a weaker enforcer that can only introduce delays but not shorten interval between events nor suppress events.…”

Verifying Policy Enforcers

“…In this work we present a possible analysis, but there are several complementary aspects worth to be analyzed. For instance, timing aspects in runtime enforcement [30,18] have not been considered, but timing could be another source of interferences. For instance, the joint activation of two enforcers may successfully cause the enforcement of some security policies, but may cause serious slow downs that dramatically annoy users.…”

A Roadmap Toward the Resilient Internet of Things for Cyber-Physical Systems

“…This approach has been pioneered by the work of Schneider [145] on security automata which halt the program whenever it deviates from a safety requirement. Since then, there has been a great effort in the RV community to define new enforcement mechanisms with primitives [146][147][148][149][150] or that support more expressive specifications [151][152][153].…”