Random Sampling over Streaming Window Joins

In this paper, we introduce a new information flow model for trusted computing systems.Different from traditional system protection models, such as access control matrix model, this model analyze the information flow in the system by tracing the operation sequences , and explains that the security status of a trusted computing system is the security attributes of information flows from input port to output port.With this model, we discuss the information channels in a trusted computing systems, and propose a "normal information flow theorem" which gives a necessary condition of the existence of normal information flow.