생체의 모델링과 Simulation

Microsoft has promoted ASP.NET’s new web services more than almost any other part of the.NET Framework. But despite their efforts, confusion is still widespread about what a web service is and, more importantly, what it’s meant to accomplish. This chapter introduces web services and explains their role in Microsoft’s vision of the programmable web. Along the way, you’ll learn about the open standards plumbing that allows web services to work and removes some of the confusion surrounding technical terms like WSDL (Web Service Description Language), SOAP, and UDDI (universal description, discovery, and integration).

Web Services Architecture

Control of Discrete-event Systems provides a survey of the most important topics in the discrete-event systems theory with particular focus on finite-state automata, Petri nets and max-plus algebra. Coverage ranges from introductory material on the basic notions and definitions of discrete-event systems to more recent results. Special attention is given to results on supervisory control, state estimation and fault diagnosis of both centralized and distributed/decentralized systems developed in the framework of the Distributed Supervisory Control of Large Plants (DISC) project. Later parts of the text are devoted to the study of congested systems though fluidization, an over approximation allowing a much more efficient study of observation and control problems of timed Petri nets. Finally, the max-plus algebraic approach to the analysis and control of choice-free systems is also considered. Control of Discrete-event Systems provides an introduction to discrete-event systems for readers that are not familiar with this class of systems, but also provides an introduction to research problems and open issues of current interest to readers already familiar with them. Most of the material in this book has been presented during a Ph.D. school held in Cagliari, Italy, in June 2011. This book constitutes the refereed proceedings of the Third International Workshop on Tools and Algorithms for the Construction and Analysis of Systems, TACAS '97, held in Enschede, The Netherlands, in April 1997. The book presents 20 revised full papers and 5 tool demonstrations carefully selected out of 54 submissions; also included are two extended abstracts and a full paper corresponding to invited talks. The papers are organized in topical sections on space reduction techniques, tool demonstrations, logical techniques, verification support, specification and analysis, and theorem proving, model checking and applications. The refereed proceedings of the 24th International Conference on Applications and Theory of Petri Nets, ICATPN 2003, held in Eindhoven, The Netherlands, in June 2003. The 25 revised full papers presented together with 6 invited contributions were carefully reviewed and selected from 77 submissions. All current issues on research and development in the area of Petri nets are addressed, in particular concurrent systems design and analysis, model checking, networking, business process modeling, formal methods in software engineering, agent systems, systems specification, systems validation, discrete event systems, protocols, and prototyping. The contents of this volume are application oriented. The volume contains a de tailed presentation of 19 applications of CP-nets, covering a broad range of ap plication areas. Most of the projects have been carried out in an industrial set ting.

Coloured Petri Nets Basic Concepts, Analysis Methods and Practical Use

We describe a largely automated and systematic analysis of TLS implementations by what we call 'protocol state fuzzing': we use state machine learning to infer state machines from protocol implementations, using only blackbox testing, and then inspect the inferred state machines to look for spurious behaviour which might be an indication of flaws in the program logic. For detecting the presence of spurious behaviour the approach is almost fully automatic: we automatically obtain state machines and any spurious behaviour is then trivial to see. Detecting whether the spurious behaviour introduces exploitable security weaknesses does require manual investigation. Still, we take the point of view that any spurious functionality in a security protocol implementation is dangerous and should be removed.

We analysed both server- and client-side implementations with a test harness that supports several key exchange algorithms and the option of client certificate authentication. We show that this approach can catch an interesting class of implementation flaws that is apparently common in security protocol implementations: in three of the TLS implementations analysed new security flaws were found (in GnuTLS, the Java Secure Socket Extension, and OpenSSL). This shows that protocol state fuzzing is a useful technique to systematically analyse security protocol implementations. As our analysis of different TLS implementations resulted in different and unique state machines for each one, the technique can also be used for fingerprinting TLS implementations.

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Protocol state fuzzing of TLS implementations

TLS is possibly the most used protocol for secure communications, with a 18-year history of flaws and fixes, ranging from its protocol logic to its cryptographic design, and from the Internet standard to its diverse implementations. We develop a verified reference implementation of TLS 1.2. Our code fully supports its wire formats, ciphersuites, sessions and connections, re-handshakes and resumptions, alerts and errors, and data fragmentation, as prescribed in the RFCs; it interoperates with mainstream web browsers and servers. At the same time, our code is carefully structured to enable its modular, automated verification, from its main API down to computational assumptions on its cryptographic algorithms. Our implementation is written in F# and specified in F7. We present security specifications for its main components, such as authenticated stream encryption for the record layer and key establishment for the handshake. We describe their verification using the F7 typechecker. To this end, we equip each cryptographic primitive and construction of TLS with a new typed interface that captures its security properties, and we gradually replace concrete implementations with ideal functionalities. We finally typecheck the protocol state machine, and obtain precise security theorems for TLS, as it is implemented and deployed. We also revisit classic attacks and report a few new ones.

/pdf/implementing-tls-with-verified-cryptographic-security-2oi9gct34l.pdf

Implementing TLS with Verified Cryptographic Security

C-O Diagrams have been introduced as a means to have a more visual representation of electronic contracts, where it is possible to represent the obligations, permissions and prohibitions of the different signatories, as well as what are the penalties in case of not fulfillment of their obligations and prohibitions. In such diagrams we are also able to represent absolute and relative timing constraints. In this paper we present a formal semantics for C-O Diagrams based on timed automata extended with an ordering of states and edges in order to represent different deontic modalities.

Timed Automata Semantics for Visual e-Contracts

In this paper we consider a Timed Automata model for the Publish/Subscribe paradigm, where special attention is given to its temporal aspects. Despite this special interest, we present a generic model for publishing and managing WS-resourses in the context of Web services with distributed resources. The model includes operations for clients to discover and subscribe to resources, with the intention of being notified when the resource property values fulfill certain conditions. Furthermore, error handling is provided in case discovery fails or a resource life has expired. Model-checking is used to verify the model soundness, by means of the UPPAAL tool, and a specific case study is presented to illustrate how the model deals with the scalability problem.

Model-checking verification of publish-subscribe architectures in web service contexts

Web services secure conversation extends Web services trust to provide mechanisms for establishing security contexts. A security context is an abstract concept that refers an authenticated state where the participants have derived secure session keys for multiples request/response exchanges. In this paper we model this protocol with the HLPSL language and we analyse it with the AVISPA toolbox.

http://www.dsi.uclm.es/retics/publications/2007/iciw07.pdf

Analysis of Web Services Secure Conversation with Formal Methods

Relationships between entities ini¾?today's increasingly interconnected context have grown in complexity and evolved from simple communication processes to more complicated distributed systems. Electronics contracts e-contracts are of general purpose and aimed to specify relationships in a wide variety of scenario, including web and cloud services, inter and intra organization, electronic banking, etc. It is in this context that we aim to develop a consistent definition for these relationships together with a set of techniques to check their proper use. In this paper we present a process algebra to describe these contract relationships and a set of formal machinery to determine whether an implementation follows the rules established by these contracts. The main formal technique used is a simulation relation where an implementation is checked step by step against a given contract. Several toy examples are provided to facilitate understanding of the formal definitions.

The Simulation Relation for Formal E-Contracts

Air pollution is currently a great concern especially in large cities. To reduce pollution levels, governments are imposing traffic restrictions. However, the decision about which grade of traffic restriction must be applied in a particular city zone is a cumbersome task. This decision depends on the pollution scenario occurred at a time period. To face this issue, we propose an analyzable and flexible intelligent system integrating Complex Event Processing (CEP) technology and Colored Petri Net (CPN) formalism to help domain experts to conduct such a decision-making process. This system uses a CEP engine to automatically analyze and correlate real air sensing data to detect pollutant averages at a particular sensor station. This produced information is then consumed in runtime by a CPN model in charge of obtaining the pollution scenarios, which are the basis to make decisions on the traffic regulations.

Gregorio Díaz

Papers

Timed Automata Semantics for Visual e-Contracts

Model-checking verification of publish-subscribe architectures in web service contexts

Analysis of Web Services Secure Conversation with Formal Methods

The Simulation Relation for Formal E-Contracts

An Intelligent System Integrating CEP and Colored Petri Nets for Helping in Decision Making About Pollution Scenarios