The elliptic curve factorization method, abbreviated ECM and sometimes also called the Lenstra elliptic curve method, is a factorization algorithm that computes a large
multiple of a point on a random elliptic curve
modulo the number to be factored . It tends to be faster than the Pollard
rho factorization and Pollard
p-1 factorization methods.
Zimmermann maintains a table of the largest factors found using the ECM. As of Jan. 2009, the largest prime factor found using the ECM had 67 decimal digits. This factor of
was found by B. Dodson on Aug. 24, 2006 (Zimmermann).
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