22,967 research outputs found
Collusion in Peer-to-Peer Systems
Peer-to-peer systems have reached a widespread use, ranging from academic and industrial applications to home entertainment. The key advantage of this paradigm lies in its scalability and flexibility, consequences of the participants sharing their resources for the common welfare. Security in such systems is a desirable goal. For example, when mission-critical operations or bank transactions are involved, their effectiveness strongly depends on the perception that users have about the system dependability and trustworthiness. A major threat to the security of these systems is the phenomenon of collusion. Peers can be selfish colluders, when they try to fool the system to gain unfair advantages over other peers, or malicious, when their purpose is to subvert the system or disturb other users. The problem, however, has received so far only a marginal attention by the research community. While several solutions exist to counter attacks in peer-to-peer systems, very few of them are meant to directly counter colluders and their attacks. Reputation, micro-payments, and concepts of game theory are currently used as the main means to obtain fairness in the usage of the resources. Our goal is to provide an overview of the topic by examining the key issues involved. We measure the relevance of the problem in the current literature and the effectiveness of existing philosophies against it, to suggest fruitful directions in the further development of the field
Privacy in an Ambient World
Privacy is a prime concern in today's information society. To protect\ud
the privacy of individuals, enterprises must follow certain privacy practices, while\ud
collecting or processing personal data. In this chapter we look at the setting where an\ud
enterprise collects private data on its website, processes it inside the enterprise and\ud
shares it with partner enterprises. In particular, we analyse three different privacy\ud
systems that can be used in the different stages of this lifecycle. One of them is the\ud
Audit Logic, recently introduced, which can be used to keep data private when it\ud
travels across enterprise boundaries. We conclude with an analysis of the features\ud
and shortcomings of these systems
An Application of Con-Resistant Trust to Improve the Reliability of Special Protection Systems within the Smart Grid
This thesis explores an application of a con-resistant trust mechanism to improve the performance of communications-based special protection systems to further enhance their effectiveness and resiliency. New initiatives in the energy sector are paving the way for the emergent communications-based smart grid technology. Smart grids incorporate modern technologies in an effort to be more reliable and efficient. However, with the benefits of this new technology comes added risk. This research utilizes a con-resistant trust mechanism as a method to quickly identify malicious or malfunctioning protection system nodes in order to mitigate the resulting instabilities in the smart grid. The feasibility and performance of this trust architecture is demonstrated through experiments comparing a simulated special protection system implemented with a con-resistant trust mechanism and without via an analysis of variance statistical model. The simulations yield positive results when implementing the con-resistant trust mechanism within the communications-based special protection system for the smart grid
Accelerating Scientific Discovery by Formulating Grand Scientific Challenges
One important question for science and society is how to best promote
scientific progress. Inspired by the great success of Hilbert's famous set of
problems, the FuturICT project tries to stimulate and focus the efforts of many
scientists by formulating Grand Challenges, i.e. a set of fundamental, relevant
and hardly solvable scientific questions.Comment: To appear in EPJ Special Topics. For related work see
http://www.futurict.eu and http://www.soms.ethz.c
Consensus-based approach to peer-to-peer electricity markets with product differentiation
With the sustained deployment of distributed generation capacities and the
more proactive role of consumers, power systems and their operation are
drifting away from a conventional top-down hierarchical structure. Electricity
market structures, however, have not yet embraced that evolution. Respecting
the high-dimensional, distributed and dynamic nature of modern power systems
would translate to designing peer-to-peer markets or, at least, to using such
an underlying decentralized structure to enable a bottom-up approach to future
electricity markets. A peer-to-peer market structure based on a Multi-Bilateral
Economic Dispatch (MBED) formulation is introduced, allowing for
multi-bilateral trading with product differentiation, for instance based on
consumer preferences. A Relaxed Consensus+Innovation (RCI) approach is
described to solve the MBED in fully decentralized manner. A set of realistic
case studies and their analysis allow us showing that such peer-to-peer market
structures can effectively yield market outcomes that are different from
centralized market structures and optimal in terms of respecting consumers
preferences while maximizing social welfare. Additionally, the RCI solving
approach allows for a fully decentralized market clearing which converges with
a negligible optimality gap, with a limited amount of information being shared.Comment: Accepted for publication in IEEE Transactions on Power System
MAX-consensus in open multi-agent systems with gossip interactions
We study the problem of distributed maximum computation in an open
multi-agent system, where agents can leave and arrive during the execution of
the algorithm. The main challenge comes from the possibility that the agent
holding the largest value leaves the system, which changes the value to be
computed. The algorithms must as a result be endowed with mechanisms allowing
to forget outdated information. The focus is on systems in which interactions
are pairwise gossips between randomly selected agents. We consider situations
where leaving agents can send a last message, and situations where they cannot.
For both cases, we provide algorithms able to eventually compute the maximum of
the values held by agents.Comment: To appear in the proceedings of the 56th IEEE Conference on Decision
and Control (CDC 17). 8 pages, 3 figure
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