## Section: New Software and Platforms

### Platforms

#### CATREL cluster

Installed in 2013, the CATREL computer cluster now plays an essential role in providing the team with the necessary resources to achieve significant computations, which illustrate well the efficiency of the algorithms developed in our research, together with their implementations.

In 2015, the CATREL cluster was in particular used for the precomputations performed for the Logjam attack [15] . It was the main computing resource for a record discrete logarithm computation in finite fields of the form ${\mathbb{F}}_{{p}^{3}}$ of 512 bits, and a larger computation for this kind of fields is currently running. It was also used intensively to optimize the sieving parameters of CADO-NFS for factoring numbers from 60 to 155 digits, in the preparation of the release 2.2.0. It was used to factor 47 large integers from nine aliquot sequences starting from 276 to 204828, the largest one being a 190-digit composite number from sequence 660. The current largest element known from an aliquot sequence has 197 digits (sequence 19560), and we expect the 200-digit frontier will be reached in 2016. Several experiments were also made with variations of the polynomial selection algorithm from [10] on RSA-896 and RSA-1024.