Fast generation of pairs (k, [k]P) for koblitz elliptic curves

Abstract

We propose a method for increasing the speed of scalar multiplication on binary anomalous (Koblitz) elliptic curves. By introducing a generator which produces random pairs (k, [k]P) of special shape, we exhibit a specific setting where the number of elliptic curve operations is reduced by 25% to 50% compared with the general case when k is chosen uniformly. This generator can be used when an ephemeral pair (k, [k]P) is needed by a cryptographic algorithm, and especially for Elliptic Curve Diffie-Hellman key exchange, ECDSA signature and El-Gamal encryption. The presented algorithm combines normal and polynomial basis operations to achieve optimal performance. We prove that a probabilistic signature scheme using our generator remains secure against chosen message attacks.