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Abstract

Rational cryptography has recently emerged as a very promising field of
research by combining notions and techniques from cryptography and game theory,
because it offers an alternative to the rather inexible traditional
cryptographic model. In contrast to the classical view of cryptography where
protocol participants are considered either honest or arbitrarily malicious,
rational cryptography models participants as rational players that try to
maximize their benefit and thus deviate from the protocol only if they gain an
advantage by doing so.
The main research goals for rational cryptography are the design of more ecient
protocols when players adhere to a rational model, the design and
implementation of automated proofs for rational security notions and the study
of the intrinsic connections between game theoretic and cryptographic notions.
In this thesis, we address all these issues.
First we present the mathematical model and the design for a new rational file
sharing protocol which we call RatFish. Next, we develop a general method for
automated verification for rational cryptographic protocols and we show how to
apply our technique in order to automatically derive the rational security
property for RatFish.
Finally, we study the intrinsic connections between game theory and
cryptography by defining a new game theoretic notion, which we call game
universal implementation, and by showing its equivalence with the notion of
weak stand-alone security.