R. Balasubramanian Neal Koblitz The Improbability That an Elliptic Curve Has Subexponential Discrete Log Problem under the Menezes - Okamoto - Vanstone Algorithm. 141-145 1998 11 J. Cryptology 2 http://link.springer.de/link/service/journals/00145/bibs/11n2p141.html db/journals/joc/joc11.html#BalasubramanianK98