@TechReport{Portz91,
  author =    "Michael Portz",
  title =     "A new class of cryptosystems based on interconnection networks",
  institution = "RWTH Aachen",
  year =      "1991",
  number =    "AIB-04-1991",
  url =       "http://aib.informatik.rwth-aachen.de/1991/1991-04.ps.gz",
}