MULTIPLYING CIRCUIT FOR ELEMENT BELONGING TO GALOIS FIELD GF (2M)

摘要

PURPOSE:To perform the arithmetic processing at a high speed by using a shift register connected to a primitive irreducible polynomial for a Galois field of GF (2m), a microprocessor and its subordinate RAM, etc., to constitute a multiplying device. CONSTITUTION:For a shift register 1 connected to a primitive irreducible polynomial of GF (24), the lowest order is regarded as X0=1 and then as X1, X2 and X3 toward the higher orders. Then the register 1 is sent toward the highest order from the lowest one when a clock CLK is applied via a lead wire 4. When X4 is obtained with transmission of X3, the X4 is written to X0=1. At the same time, the value with which the X0=1 is sent and the output received from the X4 are calculated by an exclusive OR circuit 11 and the result of this calculation is written to the X1. A microcomputer 2 contains a CPU, a RAM and a ROM together with a multiplicand register area 21, a multiplier register area 22 and a result register area 23. Thus the register 1 connected to the primitive irreducible polynomial is actuated for fast production of a desired polynomial.