METHOD AND DEVICE FOR CONDUCTING MODULAR MULTIPLICATION AND ARITHMETIC-LOGIC UNIT FOR CONDUCTING MODULAR MULTIPLICATION

摘要

A multiplication forecast method (210) is executed in order to obtain a multiplication shift value (sz). An intermediate result polynomial (Z) is shifted (214) leftward by the number of places of the multiplication shift value (sz). The module polynomial is shifted by a number of places equal to the reduction shift value (216). In a three-operand addition (218), the shifted intermediate result polynomial (Z') and the multiplicand (C) are added, and the shifted module polynomial (N') is subtracted. A transfer-interrupt function makes it possible to carry out both a Z/NZ arithmetic as well as a GF(2n) arithmetic on a single long number arithmetic-logic unit.