Comments on "Provably Sublinear Point Multiplication on Koblitz Curves and Its Hardware Implementation"

In 2008, Dimitrov et al. proposed a point multiplication algorithm on Koblitz curves using multiple-base expansions. They claimed that their algorithm is the first provably sublinear point multiplication algorithm on Koblitz curves. In this paper, we show that the well-known τ-adic NAF method is already sublinear and also guarantees a better average performance.