A New Architecture for Intrusion-Tolerant Web Services Based on Design Diversity Techniques

Web services are the realization of service-oriented architecture (SOA). Security is an important challenge of SOAP-based Web services. So far, several security techniques and standards based on traditional security mechanisms, such as encryption and digital signature, have been proposed to enhance the security of Web services. The aim has been to employ the concepts and techniques of fault-tolerant computing to make Web services more secure, which is called intrusion-tolerance. Intrusion-tolerance means the continuous delivery of services in presence of security attacks, which can be used as a fundamental approach for enhancing the security of Web services. In this paper, we propose a novel architecture for intrusion-tolerant Web services with emphasis on intrusion-tolerance concepts and composite Web service techniques. The proposed architecture, which is called design-diverse intrusion-tolerant Web service (DDITWS), takes the advantages of design diversity techniques. For Web service composition, BPEL4WS is used. Formal modeling and verification of the proposed architecture is performed using colored Petri nets (CPNs) and CPN Tools. We have checked the behavioral properties of the model to ensure its correctness. The reliability and security evaluation of the proposed architecture is also performed using a stochastic Petri net (SPN) model and the SHARPE tool. The results show that the reliability and mean-time-to-security-failure (MTTSF) in the proposed architecture are improved.