Collusion-Preserving Computation

  • Joël Alwen
  • Jonathan Katz
  • Ueli Maurer
  • Vassilis Zikas
Conference paper

DOI: 10.1007/978-3-642-32009-5_9

Volume 7417 of the book series Lecture Notes in Computer Science (LNCS)
Cite this paper as:
Alwen J., Katz J., Maurer U., Zikas V. (2012) Collusion-Preserving Computation. In: Safavi-Naini R., Canetti R. (eds) Advances in Cryptology – CRYPTO 2012. Lecture Notes in Computer Science, vol 7417. Springer, Berlin, Heidelberg

Abstract

In collusion-free protocols, subliminal communication is impossible and parties are thus unable to communicate any information “beyond what the protocol allows.” Collusion-free protocols are interesting for several reasons, but have specifically attracted attention because they can be used to reduce trust in game-theoretic mechanisms. Collusion-free protocols are impossible to achieve (in general) when all parties are connected by point-to-point channels, but exist under certain physical assumptions (Lepinksi et al., STOC 2005) or when parties are connected in specific network topologies (Alwen et al., Crypto 2008).

We provide a “clean-slate” definition of the stronger notion of collusion preservation. Our goals in revisiting the definition are:
  • To give a definition with respect to arbitrary communication resources (including as special cases the communication models from prior work). We can then, in particular, better understand what types of resources enable collusion-preserving protocols.

  • To construct protocols that allow no additional subliminal communication when parties can communicate via other means. (This property is not implied by collusion-freeness.)

  • To support composition, so protocols can be designed in a modular fashion using sub-protocols run among subsets of the parties.

In addition to proposing the definition, we explore implications of our model and show a general feasibility result for collusion-preserving computation of arbitrary functionalities. We formalize a model for concurrently playing multiple extensive-form, mediated games while preserving many important equilibrium notions.

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Copyright information

© International Association for Cryptologic Research 2012 2012

Authors and Affiliations

  • Joël Alwen
    • 1
  • Jonathan Katz
    • 2
  • Ueli Maurer
    • 1
  • Vassilis Zikas
    • 2
  1. 1.ETH ZürichZürichSwitzerland
  2. 2.University of MarylandCollege ParkUSA