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236
Process Algebras for Quantitative Analysis
, 2005
"... In the 1980s process algebras became widely accepted formalisms for describing and analysing concurrency. Extensions of the formalisms, incorporating some aspects of systems which had previously been abstracted, were developed for a number of different purposes. In the area of performance analysis m ..."
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Cited by 47 (6 self)
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In the 1980s process algebras became widely accepted formalisms for describing and analysing concurrency. Extensions of the formalisms, incorporating some aspects of systems which had previously been abstracted, were developed for a number of different purposes. In the area of performance analysis models must quantify both timing and probability. Addressing this domain led to the formulation of stochastic process algebras. In this paper we give a brief overview of stochastic process algebras and the problems which motivated them, before focussing on their relationship with the underlying mathematical stochastic process. This is presented in the context of the PEPA formalism.
PEPA nets: A structured performance modelling formalism
 Performance Evaluation
, 2003
"... In this paper we describe a formalism which uses the stochastic process algebra PEPA as the inscription language for labelled stochastic Petri nets. Viewed in another way, the net is used to provide a structure for linking related PEPA systems. The combined modelling language naturally represents su ..."
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Cited by 41 (23 self)
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In this paper we describe a formalism which uses the stochastic process algebra PEPA as the inscription language for labelled stochastic Petri nets. Viewed in another way, the net is used to provide a structure for linking related PEPA systems. The combined modelling language naturally represents such applications as mobile code systems where the PEPA terms are used to model the program code which moves between network hosts (the places in the net). We describe the implementation of a tool to support this modelling formalism and apply this to model a hierarchical cellular network. 1
Probabilistically accurate program transformations
 In SAS
, 2011
"... Abstract. The standard approach to program transformation involves the use of discrete logical reasoning to prove that the transformation does not change the observable semantics of the program. We propose a new approach that, in contrast, uses probabilistic reasoning to justify the application of t ..."
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Cited by 38 (14 self)
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Abstract. The standard approach to program transformation involves the use of discrete logical reasoning to prove that the transformation does not change the observable semantics of the program. We propose a new approach that, in contrast, uses probabilistic reasoning to justify the application of transformations that may change, within probabilistic accuracy bounds, the result that the program produces. Our new approach produces probabilistic guarantees of the form P(D  ≥ B) ≤ ɛ, ɛ ∈ (0, 1), where D is the difference between the results that the transformed and original programs produce, B is an acceptability bound on the absolute value of D, and ɛ is the maximum acceptable probability of observing large D. We show how to use our approach to justify the application of loop perforation (which transforms loops to execute fewer iterations) to a set of computational patterns. 1
Probabilistic Model Checking of an Anonymity System
 Journal of Computer Security
, 2004
"... We use the probabilistic model checker PRISM to analyze the Crowds system for anonymous Web browsing. This case study demonstrates how probabilistic model checking techniques can be used to formally analyze security properties of a peertopeer group communication system based on random message ..."
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Cited by 38 (1 self)
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We use the probabilistic model checker PRISM to analyze the Crowds system for anonymous Web browsing. This case study demonstrates how probabilistic model checking techniques can be used to formally analyze security properties of a peertopeer group communication system based on random message routing among members. The behavior of group members and the adversary is modeled as a discretetime Markov chain, and the desired security properties are expressed as PCTL formulas. The PRISM model checker is used to perform automated analysis of the system and verify anonymity guarantees it provides. Our main result is a demonstration of how certain forms of probabilistic anonymity degrade when group size increases or random routing paths are rebuilt, assuming that the corrupt group members are able to identify and/or correlate multiple routing paths originating from the same sender.
PMaude: Rewritebased specification language for probabilistic object systems
 In Proc. 3rd Workshop on Quantitative Aspects of Programming Languages (QAPL’05
, 2005
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Probabilistic Analysis of Anonymity
 IN PROC. 15TH COMPUTER SECURITY FOUNDATIONS WORKSHOP
, 2002
"... We present a formal analysis technique for probabilistic security properties of peertopeer communication systems based on random message routing among members. The behavior of group members and the adversary is modeled as a discretetime Markov chain, and security properties are expressed as PCTL ..."
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Cited by 33 (1 self)
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We present a formal analysis technique for probabilistic security properties of peertopeer communication systems based on random message routing among members. The behavior of group members and the adversary is modeled as a discretetime Markov chain, and security properties are expressed as PCTL formulas. To illustrate feasibility of the approach, we model the Crowds system for anonymous Web browsing, and use a probabilistic model checker, PRISM, to perform automated analysis of the system and verify anonymity guarantees it provides. The main result of the Crowds analysis is a demonstration of how certain forms of anonymity degrade with the increase in group size and the number of random routing paths.
Analysis of probabilistic contract signing
 Journal of Computer Security
, 2003
"... (this research was performed while at SRI International) We present three case studies, investigating the use of probabilistic model checking to automatically analyse properties of probabilistic contract signing protocols. We use the probabilistic model checker PRISM to analyse three protocols: Rabi ..."
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Cited by 32 (6 self)
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(this research was performed while at SRI International) We present three case studies, investigating the use of probabilistic model checking to automatically analyse properties of probabilistic contract signing protocols. We use the probabilistic model checker PRISM to analyse three protocols: Rabin’s probabilistic protocol for fair commitment exchange; the probabilistic contract signing protocol of BenOr, Goldreich, Micali, and Rivest; and a randomised protocol for signing contracts of Even, Goldreich, and Lempel. These case studies illustrate the general methodology for applying probabilistic model checking to formal verification of probabilistic security protocols. For the BenOr et al. protocol, we demonstrate the difficulty of combining fairness with timeliness. If, as required by timeliness, the judge responds to participants ’ messages immediately upon receiving them, then there exists a strategy for a misbehaving participant that brings the protocol to an unfair state with arbitrarily high probability, unless unusually strong assumptions are made about the quality of the communication channels between the judge and honest participants. We quantify the tradeoffs involved in the attack strategy, and discuss possible modifications of the protocol that ensure both fairness and timeliness. For the Even et al. protocol, we demonstrate that the responder enjoys a distinct advantage. With probability 1, the protocol reaches a state in which the responder possesses the initiator’s commitment, but the initiator does not possess the responder’s commitment. We then analyse several variants of the protocol, exploring the tradeoff between fairness and the number of messages that must be exchanged between participants.
Performance modelling with UML and stochastic process algebras
 IEE Proceedings: Computers and Digital Techniques
, 2003
"... Abstract: We describe a software toolset which allows UML modellers to annotate their models with performance information. An equivalent performance model is extracted from the UML, solved, and the results reflected back to the UML level. Used in this way, our toolset gives a highlevel approach to ..."
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Cited by 32 (14 self)
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Abstract: We describe a software toolset which allows UML modellers to annotate their models with performance information. An equivalent performance model is extracted from the UML, solved, and the results reflected back to the UML level. Used in this way, our toolset gives a highlevel approach to software performance modelling where the benefits of the performance modelling process are achieved without significant additional notational burden.
Partial order reduction for probabilistic systems
 In Proc. 1st QEST
, 2004
"... In the past, several model checking algorithms have been proposed to verify probabilistic reactive systems. The techniques to combat the stateexplosion problem have mainly concentrated on symbolic methods with variants of decision diagrams or abstraction methods. In this paper, we show how partial ..."
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Cited by 30 (3 self)
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In the past, several model checking algorithms have been proposed to verify probabilistic reactive systems. The techniques to combat the stateexplosion problem have mainly concentrated on symbolic methods with variants of decision diagrams or abstraction methods. In this paper, we show how partial order reduction with a variant of Peled’s ample set method can be applied in the context of LTL model checking for probabilistic systems modelled by Markov decision processes. 1
Logical and stochastic modeling with SMART
, 2003
"... We describe the main features of SmArT, a software package providing a seamless environment for the logic and probabilistic analysis of complex systems. SmArT can combine dierent formalisms in the same modeling study. For the analysis of logical behavior, both explicit and symbolic statespace g ..."
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Cited by 29 (15 self)
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We describe the main features of SmArT, a software package providing a seamless environment for the logic and probabilistic analysis of complex systems. SmArT can combine dierent formalisms in the same modeling study. For the analysis of logical behavior, both explicit and symbolic statespace generation techniques, as well as symbolic CTL modelchecking algorithms, are available. For the study of stochastic and timing behavior, both sparsestorage and Kronecker numerical solution approaches are available when the underlying process is a Markov chain. In addition,