Patent attributes
A residue computing device on a Galois Field, for calculating a residue of a product of a multiplier factor and a multiplicand under a modulo, includes a gate for allowing the multiplier factor to pass therethrough when a leading bit of the multiplicand is 1, an adder for adding a temporary residue and a value obtained by the passage, a gate for allowing the modulo to pass therethrough when a leading bit of a summed value of the adder is 1, and a subtractor for subtracting the modulo from the summed value of the adder when the leading bit of the summed value is 1, wherein a process for setting a value obtained by shifting a subtracted value of the subtractor by one bit, as the temporary residue on the basis of the next clock is repeatedly performed for each clock to thereby calculate the residue.
