Fair Secure Computation (or how can I gain strategic advantage by - - PowerPoint PPT Presentation

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Fair Secure Computation (or how can I gain strategic advantage by - - PowerPoint PPT Presentation

Feb 08, 2024 143 likes •433 views

Rump Session 2016 Fair Secure Computation (or how can I gain strategic advantage by breaking fairness) Alptekin Kp Ko University Fair Secure Computation ALPTEKN KP Assistant Professor of Computer Science and Engineering

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Rump Session 2016

Fair Secure Computation (or how can I gain strategic advantage by breaking fairness)

Alptekin Küpçü

Koç University

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Fair Secure Computation

ALPTEKİN KÜPÇÜ

Assistant Professor of Computer Science and Engineering

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Secure Multi-Party Computation

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Secure Multi-Party Computation

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Secure Multi-Party Computation

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Secure Multi-Party Computation

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Y3

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SMPC in a Corporate Setting

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I OWN YOU

Y3

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Ideal World

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Ideal World

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Real World

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Simulator

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Fairness Impossible in General

  • Assume a trusted Arbiter is available
  • Only trusted for fairness, not security
  • May collude with players
  • Should not learn input/output
  • Optimistically employed
  • Must be efficient (otherwise bottleneck)

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Fairness Impossible in General

  • Assume a trusted Arbiter is available
  • Only trusted for fairness, not security
  • May collude with players
  • Should not learn input/output
  • Optimistically employed
  • Must be efficient (otherwise bottleneck)
  • Ideal TTP Real Arbiter

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Fair and Secure Computation

  • Fairness extentions and Arbiter

resolutions must be simulated

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Simulating Fairness

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SECURE 2PC SIMULATION FAIRNESS ARGUMENT

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Simulating Fairness

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SECURE and FAIR 2PC SIMULATION

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Fair and Secure Computation

  • Fairness extentions and Arbiter

resolutions must be simulated

  • Otherwise the protocol may be insecure!

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Fair and Secure Computation

  • Fairness extentions and Arbiter

resolutions must be simulated

  • Otherwise the protocol may be insecure!
  • Simulator may contact only when

fairness is guaranteed

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Simulator

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X1 X2 X3 X5 X4 X6

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Ideal World

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Y1 Y2 Y3 Y5 Y4 Y6

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Real World

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Fair and Secure Computation

  • Fairness extentions and Arbiter

resolutions must be simulated

  • Otherwise the protocol may be insecure!
  • Simulator may contact only when

fairness is guaranteed

  • Otherwise real and ideal world outputs

are distinguishable

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Fair and Secure Computation

  • Fairness extentions and Arbiter

resolutions must be simulated

  • Otherwise the protocol may be insecure!
  • Simulator may contact only when

fairness is guaranteed

  • Otherwise real and ideal world outputs

are distinguishable

  • Arbiter cannot harm security

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Our Solutions

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# Participants # Rounds # Messages 2 O(1) O(1) n O(1) O(n^2)

  • OPTIMAL asymptotic performance
  • Cut-and-choose or zero-knowledge
  • Malicious or covert
  • 2PC or MPC
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Comparison

  • Compared to related works, we provide
  • Optimal asymptotic performance
  • Constant round (not gradual release)
  • No broadcast
  • Arbiter load independent of the circuit size
  • Do not require an external payment mechanism
  • In a competitive corporate setting, how can one value

some output that is unknown beforehand?

  • Full simulation proofs
  • Arbiter cannot harm security
  • Also proven via simulation
  • Only fairness is lost if Arbiter colludes with malicious

parties

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Our Papers

  • Reading
  • Kılınç and Küpçü, CT-RSA 2015, Optimally

Efficient Multi-Party Fair Exchange and Fair Secure Multi-Party Computation

  • Kılınç and Küpçü, FC 2016, Efficiently Making

Secure Two-Party Computation Fair

  • Küpçü and Mohassel, FC 2016, Fast

Optimistically Fair Cut-and-Choose 2PC

  • Funding Acknowlegements
  • TÜBİTAK, the Scientific and Technological

Research Council of TURKEY

  • COST Action IC1306 Cryptoaction

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ALPTEKİN KÜPÇÜ

Assistant Professor of Computer Science and Engineering

http://crypto.ku.edu.tr