675 research outputs found
Generic Security Proof of Quantum Key Exchange using Squeezed States
Recently, a Quantum Key Exchange protocol that uses squeezed states was
presented by Gottesman and Preskill. In this paper we give a generic security
proof for this protocol. The method used for this generic security proof is
based on recent work by Christiandl, Renner and Ekert.Comment: 5 pages, 7 figures, accepted at IEEE ISIT 200
Learning to Reach Agreement in a Continuous Ultimatum Game
It is well-known that acting in an individually rational manner, according to
the principles of classical game theory, may lead to sub-optimal solutions in a
class of problems named social dilemmas. In contrast, humans generally do not
have much difficulty with social dilemmas, as they are able to balance personal
benefit and group benefit. As agents in multi-agent systems are regularly
confronted with social dilemmas, for instance in tasks such as resource
allocation, these agents may benefit from the inclusion of mechanisms thought
to facilitate human fairness. Although many of such mechanisms have already
been implemented in a multi-agent systems context, their application is usually
limited to rather abstract social dilemmas with a discrete set of available
strategies (usually two). Given that many real-world examples of social
dilemmas are actually continuous in nature, we extend this previous work to
more general dilemmas, in which agents operate in a continuous strategy space.
The social dilemma under study here is the well-known Ultimatum Game, in which
an optimal solution is achieved if agents agree on a common strategy. We
investigate whether a scale-free interaction network facilitates agents to
reach agreement, especially in the presence of fixed-strategy agents that
represent a desired (e.g. human) outcome. Moreover, we study the influence of
rewiring in the interaction network. The agents are equipped with
continuous-action learning automata and play a large number of random pairwise
games in order to establish a common strategy. From our experiments, we may
conclude that results obtained in discrete-strategy games can be generalized to
continuous-strategy games to a certain extent: a scale-free interaction network
structure allows agents to achieve agreement on a common strategy, and rewiring
in the interaction network greatly enhances the agents ability to reach
agreement. However, it also becomes clear that some alternative mechanisms,
such as reputation and volunteering, have many subtleties involved and do not
have convincing beneficial effects in the continuous case
An efficient fuzzy extractor for limited noise
A fuzzy extractor is a security primitive that allows
for reproducible extraction of an almost uniform key from a
non-uniform noisy source. We analyze a fuzzy extractor scheme that
uses universal hash functions for both information reconciliation and
privacy amplification. This is a useful scheme when the number of
error patterns likely to occur is limited, regardless of the error
probabilities. We derive a sharp bound on the uniformity of the
extracted key, making use of the concatenation property of universal
hash functions and a recent tight formulation of the leftover hash
lemma
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