@TechReport{bauer+:pcaprototr,
  author = 	 {Lujo Bauer and Michael A. Schneider and Edward W. Felten},
  title = 	 {A Proof-Carrying Authorization System},
  institution =  {Princeton University},
  year = 	 {2001},
  number = 	 {TR-638-01},
  month = 	 apr,
  url =          {http://www.ece.cmu.edu/~lbauer/papers/pcaprototr.pdf}
}