Denial of Service (DoS)/Distributed DoS (DDoS) attack is an eminent threat to an Authentication Server (AS), which is used to guard access to firewalls, virtual private networks and resources connected by wired/wireless networks. In this paper, a new protocol called Identity-Based Privacy-Protected Access Control Filter (IPACF) is proposed to counter DoS/DDoS attacks. The IPACF is stateless for both user and AS since a user and responder must authenticate each other. The value and identity for authentication are changed in every frame. Thus, the privacy of both user and server is protected. The performance of the implementation is reported in this paper. In order to counter more DoS/DDoS attacks that issue fake requests, parallel processing technique is used to implement the AS. The performance comparison of dual server and single server is also reported. To study the capability of IPACF when facing massive DDoS attacks, simulations using OPNET for a network consisting of 1000 nodes with 10 Gbps pipe to the AS are carried out. The simulations show that the performance of AS has very little degradation in terms of packet latency and CPU utilisation for users. Queueing models are used to compare simulations and agreement between models and simulations is acceptable.

Authentication is an essential premise for deploying wireless LAN inter-network roaming in the real world. The technical challenge lies in the fact that a visited network does not initially have the authentication credentials of a roaming user. Existing solutions require that authentication is performed via three-party communications: user to visited network to home network. In this paper, a new concept that mutual authentication between a visited network and a roaming user can be performed locally without the contact with user's home network is proposed. This new protocol not only satisfies the roaming authentication requirements, but also has efficiency in terms of authentication time delay.

A denial of service (DoS) attack is a well-known problem for networks. Although many research papers have addressed the problem of DoS attacks, some drawbacks still exit. The major problem is this: when a responder receives a request or key message, and system resources are required to verify that the request has been sent from a legitimate user, the additional computing time and memory storage involved provides an adversary the opportunity to launch a DoS attack. In order to prevent this attack, we present a new protocol called the identity-based dynamic access control filter (IDF), which checks every filter value on every received frame to determine if they have permission to enter the system and use system resources. In this paper we focus on wireless network protection, but the same concept can be applied to a wired network as well. A performance analysis of the critical step used in preventing a DoS attack is conducted and the result is compared with other public key-based schemes.

A brief review of the principles of stereoscopy is given followed by a discussion of candidate methods for providing stereoscopic viewing of display data. An analog computer implementation of a stereoscopic graphics display system is described. The analog implementation provides real-time display capability but has no data storage capability. Implementation with a small digital computer provides data storage but is significantly slower for displaying dynamic changes in the data. Other points of comparison between the two systems are given with the conclusion that a hybrid system would combine good features of both. Experimental evaluation relative to eye fatigue is given for three specific viewing techniques. Example stereograms are given for both the digital and analog systems. Of particular interest was application of the display system for viewing biomedical data, as illustrated by an example display of a vectorcardiogram.

A general class of adaptive replacement schemes for use in paged memories is developed. One such algorithm, called SIM, is simulated using a probability model that generates memory traces, and the results of the simulation of this adaptive scheme are compared with those obtained using the best nonlookahead algorithms. A technique for implementing this type of adaptive replacement algorithm with state of the art digital hardware is also presented.

This note presents a method for designing and implementing a dynamic priority assignment memory-access conflict-resolution circuit for use in multiprocessing systems with K processors. A decision rule which establishes the priority, assignment is given and an example which illustrates the techniques is also discussed.