5,778 research outputs found
A Rational Approach to Cryptographic Protocols
This work initiates an analysis of several cryptographic protocols from a
rational point of view using a game-theoretical approach, which allows us to
represent not only the protocols but also possible misbehaviours of parties.
Concretely, several concepts of two-person games and of two-party cryptographic
protocols are here combined in order to model the latters as the formers. One
of the main advantages of analysing a cryptographic protocol in the game-theory
setting is the possibility of describing improved and stronger cryptographic
solutions because possible adversarial behaviours may be taken into account
directly. With those tools, protocols can be studied in a malicious model in
order to find equilibrium conditions that make possible to protect honest
parties against all possible strategies of adversaries
Privacy-Preserving Trust Management Mechanisms from Private Matching Schemes
Cryptographic primitives are essential for constructing privacy-preserving
communication mechanisms. There are situations in which two parties that do not
know each other need to exchange sensitive information on the Internet. Trust
management mechanisms make use of digital credentials and certificates in order
to establish trust among these strangers. We address the problem of choosing
which credentials are exchanged. During this process, each party should learn
no information about the preferences of the other party other than strictly
required for trust establishment. We present a method to reach an agreement on
the credentials to be exchanged that preserves the privacy of the parties. Our
method is based on secure two-party computation protocols for set intersection.
Namely, it is constructed from private matching schemes.Comment: The material in this paper will be presented in part at the 8th DPM
International Workshop on Data Privacy Management (DPM 2013
Computational Extensive-Form Games
We define solution concepts appropriate for computationally bounded players
playing a fixed finite game. To do so, we need to define what it means for a
\emph{computational game}, which is a sequence of games that get larger in some
appropriate sense, to represent a single finite underlying extensive-form game.
Roughly speaking, we require all the games in the sequence to have essentially
the same structure as the underlying game, except that two histories that are
indistinguishable (i.e., in the same information set) in the underlying game
may correspond to histories that are only computationally indistinguishable in
the computational game. We define a computational version of both Nash
equilibrium and sequential equilibrium for computational games, and show that
every Nash (resp., sequential) equilibrium in the underlying game corresponds
to a computational Nash (resp., sequential) equilibrium in the computational
game. One advantage of our approach is that if a cryptographic protocol
represents an abstract game, then we can analyze its strategic behavior in the
abstract game, and thus separate the cryptographic analysis of the protocol
from the strategic analysis
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