Human-oriented encryption: from Solitaire to Multitaire

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Human-oriented encryption from Solitaire to
Multitaire
Jean-Jacques Quisquater and BoF
participants UCL Crypto Group Université
catholique de Louvain jjq_at_dice.ucl.ac.be http//u
clcrypto.org August 16, 2005 Rump session
Crypto
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Solitaire (Bruce Schneier)

• http//www.schneier.com/solitaire.html
• Solitaire gets its security from the inherent
  randomness in a shuffled deck of cards. By
  manipulating this deck, a communicant can create
  a string of "random" letters that he then
  combines with his message. Of course Solitaire
  can be simulated on a computer, but it is
  designed to be implemented by hand.
• Solitaire may be low-tech, but its security is
  intended to be high-tech.

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BoF, this afternoon

• Ten people discussed during one hour,
• How to improve,
• How to use many people not only one.

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Ideas

• Use pro magicians in order to perform very good
  and reproductible shuffles
• Brent Morris (NSA) likes to say that he's the
  only person with a doctorate in card shuffling
• Diaconis, P., R.L. Graham, and W.M. Kantor.
  1983. The mathematics of perfect shuffles.
  Advances in Applied Mathematics 4175.
• Morris, S.B. 1998. Magic Tricks, Card Shuffling,
  and Dynamic Computer Memories The Mathematics of
  the Perfect Shuffle. Washington, D.C.
  Mathematical Association of America.

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More techniques

• Using automata theory (life game of Conway?)
• Simulating a large nonlinear feedback register
  by using a lot of people around a table and cards
  for storing and communicating information
  (flipping card) here a lot of problems appear
  and many optimisations are possible
• Random generation?
• Use of other games (Chess, Go, ...?),

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Conclusions

• Many open problems.
• Performances, new criteria of design, taxonomy,
  ...
• But is it useful?
• Yes, creating a funny BoF and giving a rump
  talk. Thanks to the participants. More next year.