Patent ID: 6275837
Filing Date: 2001-08-14
Classification: G06F

Abstract:
A method for implementing a Pfield operation defined according to the Montgomery method by P.sub.field (A, B).sub.N =A*B*I mod N, with A, B and N being integers encoded respectively on .alpha., b and n words of k bits, with N being an odd-parity number, with b and n being non-zero integers smaller than or equal to an integer m, and with .alpha. and m being non-zero integers, the method comprising the steps of:successively receiving words A.sub.i-1 of k bits of A in a first k bit register;storing B in a second m*k bit shift register;storing an updated data element S(i) in a third m*k bit shift register;storing N in a fourth m*k bit shift register, the second to fourth registers being organized in banks of m sub-registers for enabling shifts by k bit words;performing a first k bit shifting of least significant words in the second to fourth registers for serial production of an intermediate data element Y.sub.0 =((-N.sub.0.sup.-1 mod 2.sup.k)*(B*A.sub.i-1 +S(i-1)) mod 2.sup.k for storing in a fifth k bit register; andperforming a second n*k bit shifting of the words B, S(i-1) and N stored in the second to fourth registers for serial production of the updated data element S(i).