Fuzzy time is a collection of techniques that reduces the bandwidths of covert timing channels by making all clocks available to a process noisy. Developed in response to the problems posed by high-speed hardware timing channels, fuzzy time has been implemented in the VAX security kernel. Fuzzy time has proven to be highly effective against the timing channels in the VAX security kernel. Not only does fuzzy time close the high-speed channels, it does so at a much lower-than-anticipated performance cost. It is believed that the VAX security kernal managed to meet the covert channel guidelines while maintaining a good balance between security and performance.
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