Redundancy is then added to the fragments to tolerate fragment modification or destruction. Various types of scattering are employed to isolate the fragments so that intrusion into a part of the system would provide access to only isolated fragments. Topological scattering distributes the fragments over different storage sites and communication channels. Mixing the fragments with other data and in a random order of transmission is time scattering. Frequency scattering transmits the fragments at various frequencies.
Some operations require cooperation among several entities.
This is called privilege scattering. The demonstration clearly shows the power of these techniques to help provide for security and fault tolerance in a distributed computational system. The research program at LAAS covers the full range of activities in dependable computing from fault tolerance to fault removal and forecasting. The development of basic concepts of dependability to place a consistent formulation of terminology and notation on the whole set of concepts, methods, and techniques is a unifying aspect of their program. They have produced a very comprehensive development model that explicitly emphasizes dependability and includes it as a major design criterion.