ARITHMETIC UNIT AND CIPHER PROCESSOR

摘要

PROBLEM TO BE SOLVED: To perform operation in an extension field of 2 in addition to integer type operation only by adding minimum architecture by placing a multiplying circuit in operation by propagating a carry or without propagating the carry. SOLUTION: On a coprocessor 1, an integer type multiplying circuit 11 performs integer type multiplication between data X in a buffer X and data Y in a buffer Y and outputs the result to a selector 13. A circuit 12 for multiplication in the extension field of 2 performs multiplication in the extension field of 2 by the data X and data Y and outputs the result to a selector 13. The difference between the integer operation by the integer type multiplying circuit 11 and extension field multinomial operation of 2 by the multiplying circuit 12 is based on whether or not there is a carry (carry propagation). The selector 13 is switched according to the control signal S1 from a control part 5. An adding circuit 14 and an adding circuit 15 also switch integer type addition and addition in the extension field of 2 with the control signal S1.