Vehicular ad hoc network (VANET) is a wireless ad hoc network that operates in a vehicular environment to provide communication between vehicles. VANET can be used by a diverse range of applications to improve road safety. Cooperative collision warning system (CCWS) is one of the safety applications that can provide situational awareness and warning to drivers by exchanging safety messages between cooperative vehicles. Currently, the routing strategies for safety message dissemination in CCWS are scoped broadcast. However, the broadcast schemes are not efficient as a warning message is sent to a large number of vehicles in the area, rather than only the endangered vehicles. They also cannot prioritize the receivers based on their critical time to avoid collision. This paper presents a more efficient multicast routing scheme that can reduce unnecessary transmissions and also use adaptive transmission range. The multicast scheme involves methods to identify an abnormal vehicle, the vehicles that may be endangered by the abnormal vehicle, and the latest time for each endangered vehicle to receive the warning message in order to avoid the danger. We transform this multicast routing problem into a delay-constrained minimum Steiner tree problem. Therefore, we can use existing algorithms to solve the problem. The advantages of our multicast routing scheme are mainly its potential to support various road traffic scenarios, to optimize the wireless channel utilization, and to prioritize the receivers.

Traditionally, network-based intrusion detection systems (NIDS) monitor network traffic for signs of malicious activities. However, with the growing use of virtual private networks (VPNs) that encrypt network traffic, the NIDS can no longer analyse the encrypted data. This essentially negates any protection offered by the NIDS. Although the encrypted traffic can be decrypted at a network gateway for analysis, this compromises on data confidentiality. In this paper, we propose a detection framework which allows a traditional NIDS to continue functioning, without compromising the confidentiality afforded by the VPN. Our approach uses Shamir's secret-sharing scheme and randomised network proxies to enable detection of malicious activities in encrypted channels. Additionally, this approach is able to detect any malicious attempts to forge network traffic with the intention of evading detection. Our experiments show that the probability of a successful evasion is low, at about 0.98% in the worst case. We implement our approach in a prototype and present some preliminary results. Overall, the proposed approach is able to consistently detect intrusions and does not introduce any additional false positives.

A novel user-centric authorisation framework suitable for e-commerce in an open environment is proposed. The credential-based approach allows a user to gain access rights anonymously from various service providers who may not have pre-existing relationships. Trust establishment is achieved by making use of referrals from external third parties in the form of Anonymous Attribute Certificates. The concepts of One-task Authorisation Key and Binding Signature are proposed to facilitate pseudonymity in authorisation service. These mechanisms enhance user privacy and tackle the problem of scalability in identity-based access control systems.

This paper introduces location-based security services and discusses a new model for tamper-resistant location determination. These location-based security services are demonstrated in terms of a framework for both WAP and web-based Internet applications, which facilities the acquisition of location using the proposed model for tamper-resistant location determination. The framework is realized in two example applications that utilize location-based security services to enhance access control and audit facilities.

As the use of information technology is increasing rapidly in organizations around the world, an important task is to design global networks with high security, eÆciency and functionality.While centralized systems have the advantages of simpli ed management, they face the problems of bottleneck and single point of failure.In this paper, we propose a new authorization scheme that operates over existing centralized authentication mechanisms.The goal is to enhance the performance and scalability in a centrally administered security architecture.A new technique of using one-shot authorization toke n s i s i n troduced.It facilitates a mechanism for updating or revocation of the access rights of users in online or o-line authorization models.A smart card is used as an authorization device in addition to its traditional function of user authentication.This scheme provides the mobility for users and the exibility in coping with dierent access control policies in a cross domain multi-application environment.