Roberto Maria Avanzi Clemens Heuberger Helmut Prodinger Scalar Multiplication on Koblitz Curves Using the Frobenius Endomorphism and Its Combination with Point Halving: Extensions and Mathematical Analysis. 249-270 2006 46 Algorithmica 3-4 http://dx.doi.org/10.1007/s00453-006-0105-9 db/journals/algorithmica/algorithmica46.html#AvanziHP06