Parallel Formulations of Scalar Multiplication on Koblitz Curves

Abstract

We present an algorithm that by using the τ and τ-1 Frobenius operators concurrently allows us to obtain a parallelized version of the classical τ-and-add scalar multiplicationalgorithm for Koblitz elliptic curves. Furthermore, we report suitable irreducible polynomials that lead to efficient implementations of both τ and τ-1, thus showing that our algorithm canbe effectively applied on all the NIST-recommended curves. We also present design details of software and hardware implementations of our procedure. In a two-processor workstation soft-ware implementation, we report experimental data showing that our parallel algorithm is able to achieve a speedup factor of almost 2 when compared with the standard sequential point multipli-cation. In our hardware implementation, the parallel version yields a more modest acceleration of 17% when compared with the traditional point multiplication algorithm. Although the focus ison Koblitz curves, analogous strategies are discussed for other curves, in particular for random curves over binary fields.