University of Tartu - ©2011 unruh - Last update: 02.06.2011 10:54
Date: 20/04/2011 Location: J. Liivi 2, room 225 (note the room change!)
Speaker: Dominique Unruh
Title: Quantifying coercion-resistance - a game-theoretic analysis
Abstract:
Cryptographic protocols can be broken in many ways. Besides attacking the underlying algorithms, one can attack the users. By threatening reprisal (i.e., by coercing), one can force a user to deviate from a protocol to that user's disadvantage. For example, in a voting protocol, one might force an honest voter to vote for a particular candidate. The ability of a protocol to withstand such attacks is called coercion-resistance.
Coercion-resistance has been extensively studied in cryptography. Yet, a full understanding even of the definition of coercion-resistance has still to be reached.
In this talk, we present a new definition of coercion-resistance, based on a game-theoretic view on coercion. Besides more directly modeling why people can be coerced, the new notion also allows to quantify the precise amount of coercibility of a protocol. We argue that standard approaches are not well-suited for such quantitative analyses.