Abstraction by set-membership

We propose in this paper a slight modification of the Knuth and Bendix algorithm for solving the equality problem in non-equational theories defined by a set of Horn clauses. We prove that the completeness property of the algorithm is then preserved, provided that a weak axiomatization of boolean calculus and equality has been given to the algorithm. In particular, we need only the reflexivity axiom for equality.This algorithm can also be interpreted as the extension to Horn clauses of the resolution/narrowing algorithm proposed by Lankford [LA], which applies only when the equality predicate does not occur positively in non-unit clauses. We give some examples of theorems proved by this method, which show its efficiency in comparison with other paramodulation-based methods.Another application of the Knuth and Bendix algorithm is the proof by induction (Musser [MU], Huet-Hullot [HH], and others). We show that our version of the completion algorithm can be used for proving universally quantified formulas (not only equations) in the initial model defined by a set of Horn clauses.KeywordsNormal FormInference RuleEquational TheoryCritical PairValid ConsequenceThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Web servers and the Web services associated with them have become increasingly important in the last few years. Online banking, e-mail, and money, business- to-business (B2B), and business-to-client (B2C) transactions are growing rapidly. It is difficult to imagine modern business without these forms of networking. However, there are also significant negative aspects. In many cases, due to competitive pressures, companies and government agencies had to implement these services very fast, often too fast and without any appreciation of the concepts of security and protection. As a consequence, it turns out that a hacker can misuse with little effort these Web services or compromise the underlying database (e.g., to obtain access to credit cards numbers or social insurance information). A very significant percentage of the population in developed and developing countries is using wired and wireless connections for reading e-mails, accessing newsgroups, or using Internet banking. All these services are running on a Web server. Most Web servers are running the Apache or the Microsoft Internet Information Server (IIS) (all versions of both servers [Apache 1.3.x/2.x, IIS 3-6]) (Netcraft, 2006). Of these, older versions of the Internet Information Server are especially vulnerable to numerous attacks. Therefore, an attacker is in a position to break, with little effort, into many Web servers running IIS 4 or 5. However, the Apache Web server (running on Windows systems) is also vulnerable to similar attacks. Moreover, using a Web server based on UNIX or Linux is not a guarantee for a secure system. UNIX and Linux systems are also affected by inherent weaknesses and vulnerabilities such as buffer overflows and the handling of format strings (ZDNet, 2006). Readers who like to have more general insight are referred to works by Leiss (1990) and Garfinkel and Spafford (2002). These books give broader perspectives on Internet security.

Web services technologies change the software industry drastically by developing and integrating enterprise web services and applications in order to enable the users to access them. There are several research initiatives in the field of Web services for enterprise applications. However, none of the initiatives have attempted for web applications pertaining to academic institution using Web services technology. Web service composition is the combination of web services from different service providers to create a more sophisticated, value added web service to the web users. Researchers put on efforts to bring out the state-of-the art in web services technologies and security technologies for web services. The composition of web services is another promising area for research and development. A study reveals that there are number of approaches providing secure web services. However, there is no attempt made so far to secure the services at multi-level. This paper proposes a Multi-level Secured Framework (MLSF) for the students, faculty and employees of the academic institutions which provides secured composite web services such as admission service, fees payment service, library service, personalized service and so on. The MLSF enhances the security at various levels such as user level, device level, web services level and institution level.

We present material on how to use the architectures and technologies and how to understand the specifications that are available to build a secure Web Services system. Since this technology is rapidly changing, we present the theory behind the models and explain the thinking behind many of the security specifications that are at the forefront of the technology today. Our emphasis is on showing you how to build and understand the complexities of a secure end-to-end Web Services system. This book gives you both a detailed technical understanding of the major components of an end-to-end enterprise security architecture and a broad description of how to deploy and use Web Services security technologies to protect your corporation and its interaction with the outside world.

A Web Service Architecture for Enforcing Access Control Policies

Web service architectures have gained popularity in recent years within the scientific grid research community. One reason for this is that web services allow software and services from various organizations to be combined easily to provide integrated and distributed applications. However, most applications developed and used by scientific communities are not web-service-oriented, and there is a growing need to integrate them into grid applications based on service-oriented architectures. In this paper, we describe a framework that allows scientists to provide a web service interface to their existing applications as web services without having to write extra code or modify their applications in any way. In addition, application providers do not need to be experts in web services standards, such as Web Services Description Language, Web Services Addressing, Web Services Security, or secure authorization, because the framework automatically generates these details. The framework also enables users to discover these application services, interact with them, and compose scientific workflows from the convenience of a grid portal.

Management applications of the Web Service Offerings Language (WSOL)

The popularity of web services has largely influenced the way in which enterprise business is conducted. Since web services enable easy accessibility of data, dynamic connections, and relatively less human interventions, ensuring confidentiality and integrity of data that is transmitted via web services protocols becomes more significant. If a single service does not fulfill the service consumer requirements, it is necessary to compose several web services, which together satisfy the user requirements. Security attacks occur on SOAP messages that are communicated among web services while accessing a service or during service composition. Most of the existing works on web services security have provided solutions only for ensuring client authentication, confidentiality, and integrity of information in network layer and not in application layer. WS-Security and XML based web service security also provides message layer security in network layer and not in application layer. Hence, a novel approach that prevents the message alteration attack on SOAP messages and a security solution that detects and overcomes XML injection attack have been proposed in this paper. Our approach uses pluggable APIs in the service provider side and security services in the middleware side. The attacks were simulated and non-vulnerability of the proposed solutions to these attacks have been verified.

To address the challenges in Web services security, the author firstly analyzed threats facing Web services and related security standards, presented integrated security framework based on use of authentication, authorization, confidentiality, and integrity mechanisms for Web services, and proposed how to integrate and implement these security mechanisms in order to make Web services robust against the attacks.

Web services (WS) are considered amongst the most successful and convenient way which can take the advantages of the Internet in a flexible and reusable manner. WS constitute now the corner stone of any exchanged transaction over the Internet between any given organizations or more specifically between a client and a provider. Unfortunately, despite the considerable efforts made by researchers of this field in the recent years, security and flexibility of WS still constitute a big challenge. So far WS and the corresponding providers’ URLs are, indeed, advertised on specific UDDIs (Universal Description, Discovery and Integration) where the only role to be achieved is limited to the advertisement. As such, after finding the requested service any given client contacts the right provider to negotiate the service access procedure. These first contacts between clients and providers are usually unprotected (not Encrypted) yielding enough room for Hackers to intrude into these unprotected messages. To solve this problem, we proposed in our previous study [12] a new idea based on the utilization of PKI and the improvement of the UDDI which must play in addition to its initial missions the role of a trust centre lading, thus, to secure WS. In this paper, we pursue our study by attempting to solve also the flexibility problem of WS by using agent technology. More specifically, we are concerned by the flexibility that allows to any given provided WS to be used in different ways (several possibilities of composition with other WS to achieve several missions) by a given client within a fixed delay with a single contract.

We present a method for verifying properties of imperative programs manipulating integer arrays. We assume that we are given a program and a property to be verified. The interpreter that is, the operational semantics of the program is specified as a set of Horn clauses with constraints in the domain of integer arrays, also called constraint logic programs over integer arrays, denoted CLPArray. Then, by specializing the interpreter with respect to the given program and property, we generate a set of verification conditions expressed as a CLPArray program whose satisfiability implies that the program verifies the given property. Our verification method is based on transformations that preserve the least model semantics of CLPArray programs, and hence the satisfiability of the verification conditions. In particular, we apply the usual rules for CLP transformation, such as unfolding, folding, and constraint replacement, tailored to the specific domain of integer arrays. We propose an automatic strategy that guides the application of those rules with the objective of deriving a new set of verification conditions which is either trivially satisfiable because it contains no constrained facts or is trivially unsatisfiable because it contains the fact false. Our approach provides a very rich program verification framework where one can compose together several verification strategies, each of them being implemented by transformations of CLPArray programs.

Computing abductive explanations is an important problem, which has been studied extensively in Artificial Intelligence (AI) and related disciplines. While computing some abductive explanation for a literal χ with respect to a set of abducibles A from a Horn propositional theory Σ is intractable under the traditional representation of Σ by a set of Horn clauses, the problem is polynomial under model-based theory representation, where Σ is represented by its characteristic models. Furthermore, computing all the (possibly exponentially) many explanations is polynomial-time equivalent to the problem of dualizing a positive CNF, which is a well-known problem whose precise complexity in terms of the theory of NP-completeness is not known yet. In this paper, we first review the monotone dualization problem and its connection to computing all abductive explanations for a query literal and some related problems in knowledge discovery. We then investigate possible generalizations of this connection to abductive queries beyond literals. Among other results, we find that the equivalence for generating all explanations for a clause query (resp., term query) χ to the monotone dualization problem holds if χ contains at most k positive (resp., negative) literals for constant k, while the problem is not solvable in polynomial total-time, i.e., in time polynomial in the combined size of the input and the output, unless P=NP for general clause resp. term queries. Our results shed new light on the computational nature of abduction and Horn theories in particular, and might be interesting also for related problems, which remains to be explored.

Simple object access protocol (SOAP) is the communication protocol used by web services to communicate between systems. Since SOAP messages have the ability to bypass firewalls and directly get processed by web servers, their security is critical to the security of the web servers. Secure transit of SOAP messages plays a critical role for the applicability of web services. At present, internet users authenticate themselves using credential are vulnerable to security threats in presence of active attackers. This imposes a burden on users to manage their credentials in different ways. Along with the thorough development and application for web services, the security of it has taken people's attention more and more. While web services security (WSS) can exchange safe SOAP message and enhance the security of web services, it will also have certain influence to the performance of web services. This paper explore the security vulnerability of SOAP message transaction and taking advantage of the existing technologies and solutions related to SOAP and web services, we developing a highly developed security model. This model is useful for solving the problem between security and performance contradiction.

Background/Objectives: Service oriented Architecture (SOA) infrastructures using web services are deployed by many firms worldwide. Web Services provide a standard means of inter-operation between heterogeneous software applications that run on a variety of platforms. Most of the web services are offered with HTTP over Simple Object Access Protocol (SOAP) as the underlying infrastructure. The greatest web security threat is accepting the request from the client without proper validation. The objective is to separate the application logic and the security or validation procedures which offers more advantage for software reuse since it is not necessary to recompile, when the validation or security requirements change. Methods: An Interceptor is created for validation which has the token based authentication procedures along with the steps for validating the data. The system is devised in such a way that the business logic will be triggered if and only if the data is validated and passed by the interceptor procedures. Findings: The proposed system provides a way to keep the validation and security mechanism out of application logic and hence this does not modify the existing functionality. Thus, combining all custom security as one unit of validation before hitting the business logic is the basic idea of the proposed system.

User authentication and data security are very important aspects for the deployment and proper function of biomedical grid portals, since both sensitive data issues and controlled access to grid resources must be addressed. This chapter discusses certification and security issues in biomedical grid portals and presents the security infrastructure of GRISSOM (Grids for In Silico Systems biology and Medicine) platform. The platform consists of a web-based portal and a Web Service that enables statistical analysis of microarray cDNA data with the use of EGEE Grid infrastructure. The security infrastructure addresses user authentication and access issues, data encryption, Grid secure access and Web Service Security. The appendix of the chapter contains code snapshots on how to implement secure authentication in Web Services and create user SSL certificates on demand.