Information Security and Cryptography Research Group

Collusion-Free Multiparty Computation in the Mediated Model

Joël Alwen, Jonathan Katz, Yehuda Lindell, Giuseppe Persiano, Abhi Shelat, and Ivan Visconti

Advances in Cryptology — CRYPTO 2009, Lecture Notes in Computer Science, Springer-Verlag, vol. 5677, pp. 524-540, Aug 2009.

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.

BibTeX Citation

    author       = {Joël Alwen and Jonathan Katz and Yehuda Lindell and Giuseppe Persiano and Abhi Shelat and Ivan Visconti},
    title        = {Collusion-Free Multiparty Computation in the Mediated Model},
    editor       = {Shai Halevi},
    booktitle    = {Advances in Cryptology --- CRYPTO 2009},
    pages        = {524-540},
    series       = {Lecture Notes in Computer Science},
    volume       = {5677},
    year         = {2009},
    month        = {8},
    publisher    = {Springer-Verlag},

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