Main author:
  Laurent Bercot <ska-skaware@skarnet.org>

Thanks to:
  Dan J. Bernstein <djb@cr.yp.to>
  Jean Marot <jean.marot@salle-s.org>
  Jorge Almeida <jalmeida@math.ist.utl.pt>
  Vallo Kallaste <kalts@estpak.ee>