With the dramatic growth of information exchanges within and between organizations, major concerns emerge about the assurance of information.  Without clear knowledge of the true needs for information assurance, a company may employ local, specialized solutions that are too restrictive, or nor comprehensive.  On the other hand, cost-effective, variable integrity and variable security may be economically justifiable and adequate for ertain situations and decisions.  Therefore, a new definition of information assurane has been developed following the TQM approach.  It describes assurance as a combination of information security, integrity, and significance. The requirements of information assurance are presented and have been justified on the basis of concrete results obtained from the lab experiments that were conducted.  The exeriments and results have been briefly discussed in this paper.

A lab experiment has been perfrmed using an ERP simulator to study the impact of information failure on the results of a company.  Two scenerios have been considered: correct but delayed information, and wrong information.  The influence of the length of delay, of the error size, and of the dataet concerned by the failure have also been studied.  It follows from the analysis that: -The consequences of a given information failure depend on the dataset in which the failure occurs. -For a given dataset, information failures impact depends on the failure type. -The influence of the length of delay depends on the dataset. -The influence of the error size depends on the dataset. So far companies employ local, specialized solutions that are too restrictive, or not compehensive.  The experiments presented in this paper justify economically the use of solutions with variable assurance in ERP sysems.  They also provide directions for the design of autonomous agents to handle these assurance problems.

Denial of service (DoS)attack on the Internet has become a pressing problem.In this paper,we describe and evaluate route-based distributed packet .ltering (DPF),a novel ap- proach to distributed DoS (DDoS)attack prevention.We show that DPF achieves proactiveness and scalability,and we show that there is an intimate relationship between the e .ectiveness of DPF at mitigating DDoS attack and power- law network topology.

Computer viruses are a worrying real-world problem, and a challenge to theoretical modelling. In this issue of the \‘Computer Journal\’, Erkki Makinen proposes universal machines in a critique of an earlier paper, \“A Framework for Modelling Trojans and Computer Viris Infection\” (H. Thimbleby, S. O. Anderson and P. A. Cairns, Comp. J., 41(7):444-458, 1999). This short paper is a reply by those authors.

Alice has a private input x (of any data type, such as a number, a matrix or a data set). Bob has another private input y. Alice and Bob want to cooperatively conduct a specific computation on x and y without disclosing to the other person any information about her or his private input except for what could be derived from the results. This problem is a Secure Two-party Computation (STC) problem, which has been extensively studied in the past. Several generic solutions have been proposed to solve the general STC problem; however the generic solutions are often too inefficient to be practical. Therefore, in this dissertation, we study several specific STC problems with the goal of finding more efficient solutions than the generic ones.

We introduce a number of specific STC problems in the domains of scientific computation, statistical analysis, computational geometry and database query. Most of the problems have not been studied before in the literature.

It is not possible to view a computer operating in the real world, including the possibility of Trojan Horse programs and computer viruses, as simply a finite realisation of a Turing Machine.  We consider the actions of Trojan Horses and viruses in real computer systems and suggest a minimal framework for an adequate formal understanding of the phenomena. Some conventional approaches, including biological metaphors, are shown to be inadequate; some suggestions are made towards constructing virally-resistant systems.

The purpose of the study was to determine the effect of computer viruses on disaster recovery model development.  Through a review of the literature and careful thought, the Susceptibilities/Assets/Frequencies and Expected Value Model was developed. The design of this model is unique in that it addresses the threat of computer viruses to organizational computing resources. The model consists of two concrrent processes. These processes are the management process and the prevention recovery process.  The S.A.F.E. Model is inended to function as a tool that guides and organization through the systematic assessment of areas that are essential to the development of viral recovery strategies within the organization. Computer viruses are a dynamic threat.  The S.A.F.E. Model represents an attempt to outline a process that can be utilized to develop prevention and recovery strategies to cope with this threat.