The b2/c3 problem: how big buffers overcome covert channel cynicism in trusted database systems

We present a mechanism for communication from low to high security classes that allows partial acknowledgments and flow control without introducing covert chan-nels. By restricting our mechanism to the problem of maintaining mutual consis-tency in replicated architecture database systems, we overcome the negative general results in this problem area. A queueing theory model shows that big buffers can be practical mechanisms for real database systems