1,634 research outputs found
Dynamic analysis overview and a proposed verification tool for temporal properties in security-critical software
The need for correct software is increasing as computers are proliferating in every aspect of our lives. Dynamic analysis is a possible way of
increasing the reliability of software by introducing a monitoring and verification mechanism over and above a computer system, so that if under
some unprecedented circumstance, any of its specifications are violated,
an alarm will be raised. This paper gives an overview of the literature
in the subject and also puts forward a proposal of further research and
investigation which seems to be very promising.peer-reviewe
MCMAS-SLK: A Model Checker for the Verification of Strategy Logic Specifications
We introduce MCMAS-SLK, a BDD-based model checker for the verification of
systems against specifications expressed in a novel, epistemic variant of
strategy logic. We give syntax and semantics of the specification language and
introduce a labelling algorithm for epistemic and strategy logic modalities. We
provide details of the checker which can also be used for synthesising agents'
strategies so that a specification is satisfied by the system. We evaluate the
efficiency of the implementation by discussing the results obtained for the
dining cryptographers protocol and a variant of the cake-cutting problem
The Past, Present, and Future(s): Verifying Temporal Software Properties
Software systems are increasingly present in every aspect of our society, as their deployment can be witnessed from seemingly trivial applications of light switches, to critical control systems of nuclear facilities. In the context of critical systems, software faults and errors could potentially lead to detrimental consequences, thus more rigorous methodologies beyond the scope of testing need be applied to software systems. Formal verification, the concept of being able to mathematically prove the correctness of an algorithm with respect to a mathematical formal specification, can indeed help us prevent these failures. A popular specification language for these formal specifications is temporal logic, due to its intuitive, yet precise expressions that can be utilized to both specify and verify fundamental properties pertaining to software systems. Temporal logic can express properties pertaining to safety, liveness, termination, non-termination, and more with regards to various systems such as Windows device drivers, kernel APIs, database servers, etc. This dissertation thus presents automated scalable techniques for verifying expressive temporal logic properties of software systems, specifically those beyond the scope of existing techniques. Furthermore, this work considers the temporal sub-logics fair-CTL, CTL*, and CTL*lp, as verifying these more expressive sub-logics has been an outstanding research problem. We begin building our framework by introducing a novel scalable and high-performance CTL verification technique. Our CTL methodology is unique relative to existing techniques in that it facilitates reasoning about more expressive temporal logics. In particular, it allows us to further introduce various methodologies that allow us to verify fair-CTL, CTL*, and CTL*lp. We support the verification of fair-CTL through a reduction to our CTL model checking technique via the use of infinite non-deterministic branching to symbolically partition fair from unfair executions. For CTL∗, we propose a method that uses an internal encoding which facilitates reasoning about the subtle interplay between the nesting of path and state temporal operators that occurs within CTL∗ proofs. A precondition synthesis strategy is then used over a program transformation which trades nondeterminism in the transition relation for nondeterminism explicit in variables predicting future outcomes when necessary. Finally, we propose a linear-past extension to CTL*, that being CTL*lp, in which the past is linear and each moment in time has a unique past. We support this extension through the use of history variables over our CTL∗ technique. We demonstrate the fully automated implementation of our techniques, and report our bench- marks carried out on code fragments from the PostgreSQL database server, Apache web server, Windows OS kernel, as well as smaller programs demonstrating the expressiveness of fair-CTL, CTL*, and CTL*lp specifications. Together, these novel methodologies lead to a new class of fully automated tools capable of proving crucial properties that no tool could previously prove in the infinite-state setting
Applying Formal Methods to Networking: Theory, Techniques and Applications
Despite its great importance, modern network infrastructure is remarkable for
the lack of rigor in its engineering. The Internet which began as a research
experiment was never designed to handle the users and applications it hosts
today. The lack of formalization of the Internet architecture meant limited
abstractions and modularity, especially for the control and management planes,
thus requiring for every new need a new protocol built from scratch. This led
to an unwieldy ossified Internet architecture resistant to any attempts at
formal verification, and an Internet culture where expediency and pragmatism
are favored over formal correctness. Fortunately, recent work in the space of
clean slate Internet design---especially, the software defined networking (SDN)
paradigm---offers the Internet community another chance to develop the right
kind of architecture and abstractions. This has also led to a great resurgence
in interest of applying formal methods to specification, verification, and
synthesis of networking protocols and applications. In this paper, we present a
self-contained tutorial of the formidable amount of work that has been done in
formal methods, and present a survey of its applications to networking.Comment: 30 pages, submitted to IEEE Communications Surveys and Tutorial
Flow Logic
Flow networks have attracted a lot of research in computer science. Indeed,
many questions in numerous application areas can be reduced to questions about
flow networks. Many of these applications would benefit from a framework in
which one can formally reason about properties of flow networks that go beyond
their maximal flow. We introduce Flow Logics: modal logics that treat flow
functions as explicit first-order objects and enable the specification of rich
properties of flow networks. The syntax of our logic BFL* (Branching Flow
Logic) is similar to the syntax of the temporal logic CTL*, except that atomic
assertions may be flow propositions, like or , for
, which refer to the value of the flow in a vertex, and
that first-order quantification can be applied both to paths and to flow
functions. We present an exhaustive study of the theoretical and practical
aspects of BFL*, as well as extensions and fragments of it. Our extensions
include flow quantifications that range over non-integral flow functions or
over maximal flow functions, path quantification that ranges over paths along
which non-zero flow travels, past operators, and first-order quantification of
flow values. We focus on the model-checking problem and show that it is
PSPACE-complete, as it is for CTL*. Handling of flow quantifiers, however,
increases the complexity in terms of the network to , even
for the LFL and BFL fragments, which are the flow-counterparts of LTL and CTL.
We are still able to point to a useful fragment of BFL* for which the
model-checking problem can be solved in polynomial time. Finally, we introduce
and study the query-checking problem for BFL*, where under-specified BFL*
formulas are used for network exploration
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