An FPGA Implementation for a Flexible-Length-Arithmetic Processor Employing the FDFM Processor Core Approach

Algorithms requiring fast manipulation of multiple-length numbers are usually implemented in hardware. However, hardware implementation, using HDL (Hardware Description Language) for instance, is a laborious task and the quality of the solution relies heavily on the designer expertise. The main contribution of this work is to present a flexible-lengtharithmetic processor based on FDFM (Few DSP slices and Few Memory blocks) approach that supports arithmetic operations on multiple-length numbers using FPGAs (Field Programmable Gate Array). The proposed processor has been implement on the Xilinx Virtex-6 FPGA. Arithmetic instructions of the proposed processor architecture include addition, subtraction, and multiplication of integer numbers exceeding 64-bits. To reduce the burden of implementing algorithm directly on the FPGA, applications requiring multiple-length arithmetic operations are written in a C-like language and translated into a machine program. The machine program is then transferred and executed on the proposed architecture. A 2048-bit RSA encryption/decryption implementation has been used to assess the goodness of the proposed approach. Experimental results shows that the computing time, using the proposed architecture, of a 2048-bit RSA encryption takes only 2.2 times longer than a direct FPGA implementation. Furthermore, by employing multiple FDFM cores for the same task, the computing time reduces considerably. key words: multiple-length-numbers, multiple-length-arithmetic, FPGA, RSA, montgomery modular multiplication