Collusion-Free Multiparty Computation in the Mediated Model

  • Joël Alwen
  • Jonathan Katz
  • Yehuda Lindell
  • Giuseppe Persiano
  • abhi shelat
  • Ivan Visconti
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5677)


Collusion-free protocols prevent subliminal communication (i.e., covert channels) between parties running the protocol. In the standard communication model, if one-way functions exist, then protocols satisfying any reasonable degree of privacy cannot be collusion-free. To circumvent this impossibility, Alwen, shelat and Visconti (CRYPTO 2008) recently suggested the mediated model where all communication passes through a mediator. The goal is to design protocols where collusion-freeness is guaranteed as long as the mediator is honest, while standard security guarantees hold if the mediator is dishonest. In this model, they gave constructions of collusion-free protocols for commitments and zero-knowledge proofs in the two-party setting.

We strengthen the definition of Alwen et al., and resolve the main open questions in this area by showing a collusion-free protocol (in the mediated model) for computing any multi-party functionality.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • Joël Alwen
    • 1
  • Jonathan Katz
    • 2
  • Yehuda Lindell
    • 3
  • Giuseppe Persiano
    • 4
  • abhi shelat
    • 5
  • Ivan Visconti
    • 4
  1. 1.New York UniversityUSA
  2. 2.The University of MarylandUSA
  3. 3.Bar-Ilan UniversityIsrael
  4. 4.University of SalernoItaly
  5. 5.University of VirginiaUSA

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