Paper 2010/367

Starfish on Strike

Daniel J. Bernstein and Peter Birkner and Tanja Lange

Abstract

This paper improves the price-performance ratio of ECM, the elliptic-curve method of integer factorization. In particular, this paper constructs "a = -1" twisted Edwards curves having Q-torsion group Z/2 x Z/4, Z/8, or Z/6 and having a known non-torsion point; demonstrates that, compared to the curves used in previous ECM implementations, some of the new curves are more effective at finding small primes despite being faster; and precomputes particularly effective curves for several specific sizes of primes.