Modeling and analysis of concurrent systems using contour/transition-nets

This dissertation introduces a model for parallel computation, the Contour/Transitition model, which blends the strengths of transition-based systems (concurrency, conflict, and synchronization) with the strength of contour-based systems (control and data absraction) . By using contour/transition-nets to model computer communication protocols, a basis is provided for the formal modeling and analysis of cocurrent systems. The contour/transition model adds three notions to Petri net theory: invocations which corresponds to Petri net procedures: colors which model multiple instantiations of nets; and contours which permit scoping mechanisms. This dissertation develops an extension to Keller's invariant-method for parallel computation that is useful for proving properties of contour/transition-nets. The usefulness of contour/transisition-nets is demonstrated by a model of initial connection handling (a three-way handshake) for a protocol that offers virtual-circuit service (the DoD Transmission Control Protocol)

Modelling and simulation of a biometric identity-based cryptography

Government information is a vital asset that must be kept in a trusted environment and efficiently managed by authorised parties. Even though e-Government provides a number of advantages, it also introduces a range of new security risks. Sharing confidential and top-secret information in a secure manner among government sectors tend to be the main element that government agencies look for. Thus, developing an effective methodology is essential and it is a key factor for e-Government success. The proposed e-Government scheme in this paper is a combination of identity-based encryption and biometric technology. This new scheme can effectively improve the security in authentication systems, which provides a reliable identity with a high degree of assurance. In addition, this paper demonstrates the feasibility of using Finite-state machines as a formal method to analyse the proposed protocols

Analysis of security protocols using finite-state machines

This paper demonstrates a comprehensive analysis method using formal methods such as finite-state machine. First, we describe the modified version of our new protocol and briefly explain the encrypt-then-authenticate mechanism, which is regarded as more a secure mechanism than the one used in our protocol. Then, we use a finite-state verification to study the behaviour of each machine created for each phase of the protocol and examine their behaviour s together. Modelling with finite-state machines shows that the modified protocol can function correctly and behave properly even with invalid input or time delay

Specification of initial connection handling in TCP using structured Petri nets

This paper uses structured Petri nets to specify how connection establishment is handled by the DoD Transmission Control Protocol. The purpose of this paper is to demonstrate an alternate specification technique by examining its application to a portion of a protocol of reasonable complexity.Initially we briefly present the semantics of structured Petri nets. Following this, a terse discussion of the problems of establishing connections in a network takes place. This discussion centers on the use of the three-way handshake, which is used by TCP, as a solution for many of these problems. Finally, the specification of the three-way handshake used in TCP is made. The specification is presented in three sections: first, a general set of notes concerning the nature of this particular specification is discussed; second, the data definitions of the specification are given; and, third, the actual nets themselves are presented.This paper is condensed from a portion of the author's dissertation, which is still in preparation. In the interests of brevity, some components of the specification, such a retransmission handling, have been omitted. Interested readers should contact the author for a more detailed paper

Asynchronous interfaces for IOPT-Flow to support GALS systems

45th Annual Conference of the IEEE Industrial Electronics Society: Lisbon, Portugal: oct. 14-17, 2019Throughout the course of time, distributing a global clock signal over a synchronous circuit has become a demanding task as a result of the broadening size and complexity of modern circuits. Globally Asynchronous Locally Synchronous (GALS) systems emerge as a solution to the laborious task of distributing a global clock over a large circuit, through the partitioning of said circuit into smaller, and therefore, more manageable blocks. The DS-Pnet (Dataflow, Signals and Petri nets) modelling language and its associated framework IOPT-Flow focus on supporting the development of cyber-physical systems, however, they may be a strong push to the development of GALS systems, through their multiple available tools that comprise a graphical editor, a simulator and automatic code generation tools, namely a VHDL (VHSIC Hardware Description Language) code generator. In order to facilitate the implementation of said GALS system in the IOPT-Flow framework, some components were created, these work together to form asynchronous interfaces that are a crucial element to any GALS system, thus providing options to designers that intent to develop a GALS system utilizing the IOPT-Flow framework

A new biometric ID-based cryptography protocol and security analysis using Petri nets

This paper presents a Petri net (PN) approach to modelling, simulating, and analysing the new protocol we have proposed. This new protocol is an enhanced authentication scheme based on a biometric verification mechanism and identity based cryptography. A formal approach like Petri nets allows one to represent cryptographic protocols. For the sake of simplicity, a complex PN model will not be discussed in this paper until all attacks are demonstrated and the model proved to be secure. This paper shows how Petri nets are used to model, analyse and detect flaws in our new protocol. First, our proposed protocol is modelled without an adversary, and then a generic adversary model is added to examine all possible adversary behaviours. Finally we demonstrate how Petri nets can be used to analyse security threats such as man-in-the-middle attack, reflection attack, and parallel session attack on this protocol

Biometric identity-based cryptography for e-Government environment

Government information is a vital asset that must be kept in a trusted environment and efficiently managed by authorised parties. Even though e-Government provides a number of advantages, it also introduces a range of new security risks. Sharing confidential and top-secret information in a secure manner among government sectors tend to be the main element that government agencies look for. Thus, developing an effective methodology is essential and it is a key factor for e-Government success. The proposed e-Government scheme in this paper is a combination of identity-based encryption and biometric technology. This new scheme can effectively improve the security in authentication systems, which provides a reliable identity with a high degree of assurance. In addition, this paper demonstrates the feasibility of using Finite-state machines as a formal method to analyse the proposed protocols

Графы сигнальных переходов для схем асинхронного тракта данных

The paper proposes a method for constructing signal transition graphs (STGs), which are directly mapped into asynchronous circuits for data processing. The advantage of the proposed method is that the resulting circuits are not only output-persistent, but also conformant to the environment. In other approaches, the environment is specified implicitly and/or inexactly and therefore they guarantee only output persistence. The conformation can be verified if both the circuit and its environment are specified by STGs. As an example, we consider a module realizing the function AND2. This module can either wait for both 1s or evaluate the function as soon as at least one 0 arrives. For each case, we draw up a separate STG (scenario) and map it into NCL gates. To provide such a mapping, we specify the behaviors of NCL gates by STG protocols. For data path, such an STG always contains alternative branches with the so-called garbage transitions at the gate inputs. The garbage transitions on a certain wire mean that the circuit is sensitive to the delay in this wire. Ignoring the garbage may lead to a violation of conformation or/and output persistence. For example, in the combinational part of the NCL circuits, the garbage appears on the inputs of NCL gates, and therefore these circuits are not delay insensitive.В статье предлагается метод построения графов сигнальных переходов (STG), которые напрямую отображаются в схемы асинхронной обработки данных. Преимуществом предлагаемого метода является то, что полученные схемы не только неизменны по выходу (output-persistent), но и конформны внешней среде. В других подходах среда задаётся неявно и/или неточно, и поэтому они гарантируют только неизменность по выходу. Конформность можно проверить, если как схема, так и её внешняя среда заданы STG. В качестве примера мы рассматриваем модуль, реализующий функцию 2И. Этот модуль может либо ожидать лог. 1 на обоих входах, либо вычислить функцию, как только придёт хотя бы один 0. Для каждого случая мы составляем отдельный STG (сценарий) и отображаем его в элементы NCL. Чтобы обеспечить такое отображение, мы задаём поведение NCL элементов STG протоколами . Для тракта данных такой STG всегда содержит альтернативные ветви с так называемыми мусорными переключениями на входах элементов. Мусорные переключения на определенном проводе означают, что схема чувствительна к задержке в этом проводе. Игнорирование мусора может привести к нарушению конформности и/или неизменности по выходу. Например, в комбинационной части NCL схем мусор появляется на входах NCL элементов, поэтому эти схемы чувствительны к задержкам

Developing Globally-Asynchronous Locally- Synchronous Systems through the IOPT-Flow Framework

Throughout the years, synchronous circuits have increased in size and com-plexity, consequently, distributing a global clock signal has become a laborious task. Globally-Asynchronous Locally-Synchronous (GALS) systems emerge as a possible solution; however, these new systems require new tools. The DS-Pnet language formalism and the IOPT-Flow framework aim to support and accelerate the development of cyber-physical systems. To do so it offers a tool chain that comprises a graphical editor, a simulator and code gener-ation tools capable of generating C, JavaScript and VHDL code. However, DS-Pnets and IOPT-Flow are not yet tuned to handle GALS systems, allowing for partial specification, but not a complete one. This dissertation proposes extensions to the DS-Pnet language and the IOPT-Flow framework in order to allow development of GALS systems. Addi-tionally, some asynchronous components were created, these form interfaces that allow synchronous blocks within a GALS system to communicate with each other