@ARTICLE{DenningSacco81,
  AUTHOR = {D. Denning and G. Sacco},
  TITLE = {Timestamps in Key Distributed Protocols},
  JOURNAL = {Communication of the ACM},
  YEAR = 1981,
  VOLUME = 24,
  NUMBER = 8,
  PAGES = {533--535}
}

@ARTICLE{NeedhamSchroederSK78,
  AUTHOR = {R. Needham and M. Schroeder},
  TITLE = {Using Encryption for Authentication in Large Networks of Computers},
  JOURNAL = {Communications of the ACM},
  YEAR = 1978,
  VOLUME = 21,
  NUMBER = 12,
  MONTH = {December}
}