Section: New Software and Platforms

CADO-NFS

Participants : Cyril Bouvier, Alain Filbois, Pierrick Gaudry, Alexander Kruppa, Thomas Richard, Emmanuel Thomé [contact] , Paul Zimmermann.

Cado-nfs is a program to factor integers using the Number Field Sieve algorithm (NFS), originally developed in the context of the ANR-CADO project (November 2006 to January 2010).

NFS is a complex algorithm which contains a large number of sub-algorithms. The implementation of all of them is now complete, but still leaves some places to be improved. Compared to existing implementations, the Cado-nfs implementation is already a reasonable player. Several factorizations have been completed using our implementation.

Since 2009, the source repository of Cado-nfs is publicly available for download, and is referenced from the software page at http://cado-nfs.gforge.inria.fr/ . A major new release, Cado-nfs 2.1, was published in July 2014, with a bug-fix release (2.1.1) in October. Among the main improvements, the polynomial selection now runs in two stages, several unit tests have been added, various small speed-ups and bug fixes.

More and more people use Cado-nfs to perform medium to large factorizations. In February, Fabien Perigaud and Cédric Pernet from Cassidian Cybersecurity reverse-engineered a ransomware, which in the end boiled down to factoring numbers with Cado-nfs .