Re:Air-Gapped Computers Can Be Compromised Using EM Side-Cha...
by thesz on Saturday January 31, 2015 @05:05AM
(#8976354)
Self-synchronous logic does not have this kind of RF patterns. Or, at least, has it in a much more smoother way.
Self-synchronous logic does not have global clock and operations have different timings.
As an example, in a synchronous logic one has to use carry-ahead variant of adder to get worst case time to O(logN). In a self-synchronous logic regular ripple-carry adder will suffice and produce result in O(logN) time in average case (yes, O(N) in worst case, which will met with probability p=1/2^N). Even more, adding small integers of K bits will result in O(logK) operations.
This means that each operation will have different completion time in self-synchronous logic. This is due to variance in inputs and/or temperature variance.
This, in turn, means that radio emission from operation completion in self-synchronous CPU will be much more smooth than for regular CPU.
Self-synchronous logic does not have global clock and operations have different timings.
As an example, in a synchronous logic one has to use carry-ahead variant of adder to get worst case time to O(logN). In a self-synchronous logic regular ripple-carry adder will suffice and produce result in O(logN) time in average case (yes, O(N) in worst case, which will met with probability p=1/2^N). Even more, adding small integers of K bits will result in O(logK) operations.
This means that each operation will have different completion time in self-synchronous logic. This is due to variance in inputs and/or temperature variance.
This, in turn, means that radio emission from operation completion in self-synchronous CPU will be much more smooth than for regular CPU.