Web services intend to provide an application integration technology that can be successfully used over the Internet in a secure, interoperable and trusted manner. Policies are high-level guidelines defining the way an institution conducts its activities. The WS-Policy standard describes how to apply policies of security definition, enforcement of access control, authentication and logging. WS-Trust defines a security token service and a trust engine which are used by web services to authenticate other web services. Using the functions defined in WS-Trust, applications can engage in secure communication after establishing trust. BPEL is a language for web service composition that intends to provide convenient and effective means for application integration over the Internet. We address security considerations in BPEL and how to enforce them, as well as its interactions with other web services standards such as WS-Security and WS-Policy. / by Ola Ajaj. / Thesis (M.S.C.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

Hardware/Software (HW/SW) interfaces are pervasive in modern computer systems. Most of HW/SW interfaces are implemented by devices and their device drivers. Unfortunately, HW/SW interfaces are unreliable and insecure due to their intrinsic complexity and error-prone nature. Moreover, assuring HW/SW interface reliability and security is challenging. First, at the post-silicon validation stage, HW/SW integration validation is largely an ad-hoc and time-consuming process. Second, at the system deployment stage, transient hardware failures and malicious attacks make HW/SW interfaces vulnerable even after intensive testing and validation. In this dissertation, we present a comprehensive solution for HW/SW interface assurance over the system life cycle. This solution is composited of two major parts. First, our solution provides a systematic HW/SW co-validation framework which validates hardware and software together; Second, based on the co-validation framework, we design two schemes for assuring HW/SW interfaces over the system life cycle: (1) post-silicon HW/SW co-validation at the post-silicon validation stage; (2) HW/SW co-monitoring at the system deployment stage. Our HW/SW co-validation framework employs a key technique, conformance checking which checks the interface conformance between the device and its reference model. Furthermore, property checking is carried out to verify system properties over the interactions between the reference model and the driver. Based on the conformance between the reference model and the device, properties hold on the reference model/driver interface also hold on the device/driver interface. Conformance checking discovers inconsistencies between the device and its reference model thereby validating device interface implementations of both sides. Property checking detects both device and driver violations of HW/SW interface protocols. By detecting device and driver errors, our co-validation approach provides a systematic and ecient way to validate HW/SW interfaces. We developed two software tools which implement the two assurance schemes: DCC (Device Conformance Checker), a co-validation framework for post-silicon HW/SW integration validation; and CoMon (HW/SW Co-monitoring), a runtime verication framework for detecting bugs and malicious attacks across HW/SW interfaces. The two software tools lead to discovery of 42 bugs from four industry hardware devices, the device drivers, and their reference models. The results have demonstrated the signicance of our approach in HW/SW interface assurance of industry applications.

Thesis (Msc (Mathematical Sciences. Computer Science))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Model checkers are programs that automatically verify, without human assistance, that certain user-specified properties hold in concurrent software systems. Since these programs often have expensive time and memory requirements, an active area of research is the development of distributed model checkers that run on clusters. Of particular interest is how the communication between the machines can be reduced to speed up their running time. In this thesis the design decisions involved in an on-the-fly distributed model checker are identified and discussed. Furthermore, the implementation of such a program is described. The central idea behind the algorithm is the generation and distribution of data throughout the nodes of the cluster. We introduce several techniques to reduce the communication among the nodes, and study their effectiveness by means of a set of models. / AFRIKAANSE OPSOMMING: Modeltoetsers is programme wat outomaties bevestig, sonder enige hulp van die gebruiker, dat gelopende sagteware aan sekere gespesifiseerde eienskappe voldoen. Die feit dat hierdie programme dikwels lang looptye en groot geheues benodig, het daartoe aanleiding gegee dat modeltoetsers wat verspreid oor ’n groep rekenaars hardloop, aktief nagevors word. Dit is veral belangrik om vas te stel hoe die kommunikasie tussen rekenaars verminder kan word om sodoende die looptyd te verkort. Hierdie tesis identifiseer en bespreek die ontwerpsbesluite betrokke in die ontwikkeling van ’n verspreide modeltoetser. Verder word die implementasie van so ’n program beskryf. Die kernidee is die generasie en verspreiding van data na al die rekenaars in die groep wat aan die probleem werk. Ons stel verskeie tegnieke voor om die kommunikasie tussen die rekenaar te verminder en bestudeer die effektiwiteit van hierdie tegnieke aan die hand van ’n lys modelle.