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.


Signature Scheme Mediate Model Covert Channel Auxiliary Input Honest Party 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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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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