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Matt Lepinski

Possible papers associated with this exact author name in Arrow. This page groups case-insensitive exact name matches and is not a full identity disambiguation profile.

2 papers
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2

STOC Conference 2005 Conference Paper

Collusion-free protocols

  • Matt Lepinski
  • Silvio Micali
  • Abhi Shelat

Secure protocols attempt to minimize the injuries to privacy and correctness inflicted by malicious participants who collude during run-time. They do not, however, prevent malicious parties from colluding and coordinating their actions in the first place!Eliminating such collusion of malicious parties during the execution of a protocol is an important and exciting direction for research in Cryptography. We contribute the first general result in this direction: (1) We provide a rigorous definition of what a collusion-free protocol is; and (2) We prove that, under standard physical and computational assumptions ---i.e., plain envelopes and trapdoor permutations---collusion-free protocols exist for all finite protocol tasks with publicly observable actions. (Note that such tasks are allowed to have secret global state, and thus include Poker, Bridge, and other such games.Our solution is tight in the sense that, for a collusion-free protocol to exist, each of (a) the finiteness of the game of interest, (b) the public observability of its actions, and (c) the use of some type of physically private channel is provably essential.

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FOCS Conference 2005 Conference Paper

Rational Secure Computation and Ideal Mechanism Design

  • Sergei Izmalkov
  • Silvio Micali
  • Matt Lepinski

Secure computation essentially guarantees that whatever computation n players can do with the help of a trusted party, they can also do by themselves. Fundamentally, however, this notion depends on the honesty of at least some players. We put forward and implement a stronger notion, rational secure computation, that does not depend on player honesty, but solely on player rationality. The key to our implementation is showing that the ballot-box - the venerable device used throughout the world to tally secret votes securely - can actually be used to securely compute any function. Our work bridges the fields of game theory and cryptography, and has broad implications for mechanism design.

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