Software or hardware multiple word operands integer division calculation performing method for cryptographic processing system, involves obtaining reciprocal value of divisor by extracting number of most significant words of divisor

摘要

The method involves obtaining an approximate reciprocal value of a divisor by extracting a specific number of most significant words of the divisor, by adding one to extracted value and by dividing it with powers of two from the words. A partial quotient value for a round off is obtained by multiplying the reciprocal value with a remainder. The quotient value is incremented by a random value. The incremented value is multiplied by the divisor and subtracted from the remainder. The obtained value is left shifted by a number of bits and added to a quotient for accumulating the quotient. An independent claim is also included for a processor readable medium storing a program making an electronic digital processing system to perform a method of performing calculation of integer division of multiple word operands in a cryptographic processing system.