Parallel Structured Gaussian Elimination for the Number Field Sieve

This article describes a parallel algorithm for the Structured Gauss-ian Elimination step of the Number Field Sieve (NFS). NFS is the best known method for factoring large integers and computing discrete logarithms. State-of-the-art algorithms for this kind of partial sparse elimination , as implemented in the CADO-NFS software tool, were unamenable to parallel implementations. We therefore designed a new algorithm from scratch with this objective and implemented it using OpenMP. The result is not only faster sequentially, but scales reasonably well: using 32 cores, the time needed to process two landmark instances went down from 38 minutes to 20 seconds and from 6.7 hours to 2.3 minutes, respectively.