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To view virtual universities as an extension of real universities and of distant learning Institutes, new concepts in the area of distributed systems and virtual universities are needed. Mobile agents satisfy many requirements of such a highly dynamic system. Originally, mobile agents were used as a workflow system for a virtual university. These autonomous entities must next generate dynamic workflows. Examining the behaviour of ants in different situations, some conclusions regarding the use of mobile agents can be drawn. This paper presents the new ideas of a joint research project and gives an overview of the problems that confront us.

Two main areas of activity can be identified in the field of network security: the local area network and the common point between networks. Presents an overview of two projects concerning the above‐mentioned areas. While the first will concern security architectures based on active firewall components, the second presents a secure intranet solution. The combination of active firewall components with the DMZ concept can translate a security policy into reality and will result in a high level security firewall system. One of the most important security problems in an intranet is to ensure that every user has access only to the information which is relevant for his/her work. In our project this is solved using role‐dependent information access for each user.

This research aims to propose an attack that de-obfuscates codes by exploiting the properties of context-free grammars since it is important to understand the strength of obfuscation provided by context-free grammar-based obfuscators. In addition, the possibility of automatically generated transformations is explored.

As part of our empirical investigation, a development environment for obfuscating transformations is built. The tool is used to simulate a context-free obfuscator and to devise ways of reversing such transformations. Furthermore, a theoretical investigation of subset grammars and subset languages is carried out.

It is concluded that context-free grammar-based obfuscators provide limited levels of protection. Nevertheless, their application is appropriate when combined with other obfuscating techniques.

The algorithms behave as expected on a limited number of test samples. Further work is required to increase their practicality and to establish their average reliability.

This research shows how a frequency analysis attack can threaten the security of code scrambled by context-free grammar-based obfuscators.