Utilization of timed automata as a verification tool for real-time security protocols

Thesis (Master)--Izmir Institute of Technology, Computer Engineering, Izmir, 2010Includes bibliographical references (leaves: 85-92)Text in English; Abstract: Turkish and Englishxi, 92 leavesTimed Automata is an extension to the automata-theoretic approach to the modeling of real time systems that introduces time into the classical automata. Since it has been first proposed by Alur and Dill in the early nineties, it has become an important research area and been widely studied in both the context of formal languages and modeling and verification of real time systems. Timed automata use dense time modeling, allowing efficient model checking of time-sensitive systems whose correct functioning depend on the timing properties. One of these application areas is the verification of security protocols. This thesis aims to study the timed automata model and utilize it as a verification tool for security protocols. As a case study, the Neuman-Stubblebine Repeated Authentication Protocol is modeled and verified employing the time-sensitive properties in the model. The flaws of the protocol are analyzed and it is commented on the benefits and challenges of the model

Timed Automata Semantics for Analyzing Creol

We give a real-time semantics for the concurrent, object-oriented modeling language Creol, by mapping Creol processes to a network of timed automata. We can use our semantics to verify real time properties of Creol objects, in particular to see whether processes can be scheduled correctly and meet their end-to-end deadlines. Real-time Creol can be useful for analyzing, for instance, abstract models of multi-core embedded systems. We show how analysis can be done in Uppaal.Comment: In Proceedings FOCLASA 2010, arXiv:1007.499

A Few Considerations on Structural and Logical Composition in Specification Theories

Over the last 20 years a large number of automata-based specification theories have been proposed for modeling of discrete,real-time and probabilistic systems. We have observed a lot of shared algebraic structure between these formalisms. In this short abstract, we collect results of our work in progress on describing and systematizing the algebraic assumptions in specification theories.Comment: In Proceedings FIT 2010, arXiv:1101.426

Adaptive Task Automata with Earliest-Deadline-First Scheduling

Adjusting to resource changes, dynamic environmental conditions, or new usage modes are some of the reasons why real-time embedded systems need to be adaptive. This requires a rigorous framework for designing such systems, to ensure that the adaptivity does not result in invalidating the system’s real-time constraints. To address this need, we have recently introduced adaptive task automata, a framework for modeling, verification, and schedulability analysis in adaptive, hard real-time embedded systems, assuming a fixed-priority scheduler. In this work, we extend the adaptive task automata framework to incorporate the earliest-deadline-first scheduling policy, as well as enable implementation of any other dynamic scheduling policy. To prove the decidability of our model, and at the same time maintain a manageable degree of conciseness, we show an encoding of our model as a network of timed automata with clock updates. To support this, we also show that reachability in our class of timed automata with updates is decidable. Our contribution helps to streamline the process of designing safety critical adaptive embedded systems

Modelamiento y especificación de sistemas distribuidos y temporizados

El aumento en la complejidad de los sistemas distribuidos y temporizados hace que ellos sean muy difícil de modelary especificar correctamente. Diferentes métodos formales son útiles para el proceso de modelado y especificaciónde estos tipos de sistemas. Los Autómatas Temporizados (AT) y los Autómatas Temporizados Distribuidos (ATD)son los modelos formales más utilizados para modelar sistemas de tiempo real y distribuidos. Lamentablemente losalgoritmos existentes para calcular la inclusión y complementación de sus lenguajes son indecidible. En este artículo,presentaremos las lógicas (Lógica Temporalizada de Eventos Distribuidos, Lógica Temporizados de Memorizaciónde Eventos) y los autómatas (Autómatas de Eventos Distribuidos, Autómatas de Memorización de Eventos),totalmente decidibles. Estos métodos fueron diseñados para modelar, especificar, estudiar el comportamiento y enespecial verificar el buen funcionamiento de los sistemas de tiempo real y distribuidos.Increasing complexity in distributed and real-time systems makes them very hard to model and specify correctly. Different formal methods are useful for the process of modeling and specification of these kinds of systems. Timed Automata (TA) and Distributed Timed Automata (DTA) are the dominant models of distributed and realtime systems. Unfortunately, their language inclusion and complementation are undecidable. In this paper, we will present logics and automata (Distributed Event Clock Automata (DECA), Memory Event Clock Automata (RMECA), Distributed Event Clock Temporal Logic (DECTL), Memory Event Clock Temporal Logic (RMECTL) fully decidable and they were designed to modeling, specifying and studying the behavior and in particular verifying the correct operation of distributed and real-time systems

Automatic compositional verification of timed systems

Specification and verification of real-time systems are important research topics with crucial applications; however, the so-called state space explosion problem often prevents model checking to be used in practice for large systems. In this work, we present a self-contained toolkit to analyze real-time systems specified using event-recording automata (ERAs), which supports system modeling, animated simulation, and fully automatic compositional verification based on learning techniques. Experimental results show that our tool outperforms the state-of-the-art timed model checker.No Full Tex

Polychronous mode automata

International audienceAmong related synchronous programming principles, the model of computation of the Polychrony workbench stands out by its capability to give high-level description of systems where each component owns a local activation clock (such as, typically,distributed real-time systems or systems on a chip). In order to bring the modeling capability of Polychrony to the context of a model-driven engineering toolset for embedded system design, we define a diagramic notation composed of mode automata and data-flow equations on top of the multi-clocked synchronous model of computation supported by the Polychrony workbench. We demonstrate the agility of this paradigm by considering the example of an integrated modular avionics application. Our presentation features the formalization and use of model transformation techniques of the GME environment to embed the extension of Polychrony's meta-model with mode automata