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[email protected]@njupt.edu.cn or or [email protected]@itslab.csce.kyushu--u.ac.jpu.ac.jp
Research on trust and incentive mechanisms in distributed systems
based on multi-disciplinary principles
Wang YufengInformation Technology & Security Laboratory, Kyushu University
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OutlineOutline
• Introduction to Chinese academic research • Research motivations • Current research state• Research contents• Multi-disciplinary concepts and solutions
33
Introduction to myselfIntroduction to myself• Wang Yufeng, received Ph.D degree from State Key
Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunication, China, June, 2004.
• From July 2004 till June 2006, I acted as lecturer, in Nanjing University of Posts and Telecommunications.
• Presently, I act as PostDoc researcher under the supervision of Prof. SAKURAI.
• http://itslab.csce.kyushu-u.ac.jp/%7Ewfwang/index.html• Research interests: P2P, sensor networks, etc.
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Location of Location of NanjingNanjing
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Location of Location of NanjingNanjing citycity
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Security related research in ChinaSecurity related research in China
• Information Security Center (ISC) is the important part of this key lab. The present director of ISC is Prof. Yang YiXian, a very excellent young scientist in China, almost three hundred Ph.Dand master graduate student, postDoc researcher.
• http://www.bupt.edu.cn/yuanxi/introduce/jisuanji/nationalLab/• The main research fields: Networks Security; Security mobile
communications; Theory and applications of modern cryptography; Theory and applications of information hiding; Digital contents and its security; Applied security technology.etc.
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Security related research in China (cont.)Security related research in China (cont.)• The State Key Laboratory Of Information Security
(SKLOIS) http://www.is.ac.cn/, belongs to institute of software, Chinese academic of science.
• Research area: Cryptographic Theory and Technology; Security Protocols; Information Counterwork; Network and System Security
• As of July 2002, there were more than 120 researchers including visiting scholars, post-doctoral, doctoral, and masters students in SKLOIS.
• The 2nd SKLOIS Conference on Information Security and Cryptology ((Inscrypt, formerly CISC) , http://www.is.iscas.ac.cn/cisc/. Held in November 29 - December 1, 2006, Beijing, China,
• Deadline for Submission:July 15, 2006
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Other research fieldsOther research fields
• The general research fields includes: telecommunication, information technologies, computer science and technologies, electronic engineering, automatic control, optical technologies etc. the above fields are features of Beijing (Nanjing) university of Posts and Telecommunications.
• It is common to cooperate among those universities.
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Motivations and current stateMotivations and current state• Traditional system: participants behave
according to the intentions of the system architects.
• distributed networks like P2P, MANET, sensor network etc.: heterogeneous, dynamic and distributed environments
• managed by multiple administrative authorities and shared by users with different and competing interests.
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PeerPeer--toto--Peer SystemsPeer Systems• Distributed application
where nodes are:– Autonomous– Very loosely coupled– Equal in role or
functionality– Share and exchange
resources with each other• each individual
participator (peer) is self-interest (or rational)
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Quick Introduction to Classical Quick Introduction to Classical PrisonerPrisoner’’s Dilemmas Dilemma
Row Player A
Column Player BShare Not Share
3 3Reward for Mutual
Generosity0 5
5 01 1
Punishment for mutual
selfishness
Share
Not Share
Individual rationality leads to a worse outcome for both, than possible.
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SelfSelf--interest in distributed systemsinterest in distributed systems• Self-interest means that simply malicious or
faulty assumption, fail to address the challenges of rational behavior.
• Conclusion: respect peers’ rationality, and design proper incentive mechanisms to encourage peer to conduct something beneficial to the whole system, while peer pursued their own utility.
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IncentiveIncentive--compatible P2P topologycompatible P2P topology• much research on P2P topology construction
algorithms based on the peer capacity or semantic small-world model.
• ignored one fundamental problem: peers may lie about their private information to reduce the incurred overhead.
• In what interaction rules, direct revelation is peer’s first choice? And based on those interaction rule to construct P2P topology, incentive-compatible P2P topology.
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FreeridingFreeriding and whitewasherand whitewasher• P2P systems assumed two roles
simultaneously: communications infrastructure and social-economic entity.
• free-riding: contribute less to the system than they consume from it, or contribute nothing
• Whitewashing: because of anonymity, P2P system can not distinguish whitewasher from new comer.
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measurement of measurement of freeridingfreeriding• Free-riding problem
– Nearly 70% users do not share.• Tragedy of the Commons
– Nearly 50% request responses are from top 1% nodes.• Objective
– Provide Incentive to share information.– Provide Service Differentiation for users.– Provide mechanism to isolate malicious users.
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QoSQoS in distributed systemsin distributed systems• it is necessary to investigate how to
seamlessly integrate the incentive mechanisms into the QoS algorithms based on multi-discipline principles
• By QoS in P2P systems it not only means that traditional network-specific performance, but more important, application-specific performance as a whole, like reliability, availability and security etc.
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A
Trustworthy sensor communityTrustworthy sensor community
B• Although cryptography and authentication helps,
it alone is not sufficient for the unique characteristics and novel misbehaviors encountered in sensor networks.
• tools from different domains such as economics theory, statistics and data analysis will facilitate to form trustworthy community in sensor networks.
How can a user trust the information provided by the sensor network?
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Interesting applicationInteresting application-- P2P gaP2P gameme• P2P gaming is the most interesting P2P
application. But, the development of P2P games faces a significant obstacle: the issue of trust.
• In a game without trusted, centralized resources, how can competing parties ensure fairness on their own?
• it is viable to attempt to apply those research results in our proposal to P2P gaming research.
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Research contentsResearch contents
P2P Applications P2P gaming
P2P topology construction based on Incentive compatibility principle
Application Level Multicast
(ALM)
Instant Message (IM)
Peer semantic interest
Peer capacity …
QoS algorithms integrated with incentive mechanisms
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MultiMulti--disciplinary tools disciplinary tools • One clear need is to make use of the most of
research results of these different fields: mathematics, economics, information sciences, and social theory.
• Game theory, which try to understand how decision-makers interact, appears to be a natural tool for studying systems composed of autonomous entities.
• Three basic elements: player, strategy space, preference and payoff.
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MultiMulti--disciplinary Toolsdisciplinary Tools• Mechanism design: “Inverse game theory”,
given desired goals, design the game which will have the desired outcome in equilibrium when self-interested nodes pursue self-interested strategies.
• For example, if efficiency is the goal, then there is a general technique for constructing truthful mechanisms: Vickrey-Clarks-Groove (VCG) mechanism.
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Incentive compatibilityIncentive compatibility• we should respect rationality of peers, and design
proper incentive mechanisms to encourage peer to conduct something beneficial to the whole system, while peers pursued their own utility. That is incentive-compatible principle (incentive-compatibility).
• The key to overcoming the individual rationality of defection or free-riding is through encouraging reciprocity among the peers. Reciprocity can be facilitated through trust-based (reputation-based) or trade-based (token-based) approaches.
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illustration of elementary cooperationillustration of elementary cooperation
• Remuneration. In most incentive patterns, the principal entity remunerates the agent entity.– Type.– Granularity.– Assessment– Storage site
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A Taxonomy of Incentive Patterns• In trust based incentive patterns, the agent entity is stimulated
by the trust it has in the principal entity. Trust either accrues from membership (collective pattern) or it is subject to entities’behavior and, thus, adapts dynamically (community pattern). On contrary, in trade based incentive patterns, the agent entity isstimulated by an action in return that is either executed simultaneously (barter trade pattern) or promised (bond based incentive patterns).
2525
Features of incentive patternsFeatures of incentive patterns• The collective and community pattern seem to be too
restrictive with regard to their scalability and fuzzy accounting; easy to implement and can be combined with other patterns.
• Barter trade exhibits several features that are desirable :– anonymous: The participating entities do not have to disclose
their identity; – offline: Cooperation and remuneration do not require
interaction with specific third parties; – persistent: The remuneration is effective, even if the
participating entities are disconnected immediately after their cooperation.
– However, for most cooperation patterns, it is infeasible to execute a simultaneous action in return. Even so, the exchange is unlikely to be fair due to the actions’ granularity.
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Features of incentive patterns (cont.)Features of incentive patterns (cont.)
• The introduction of various bonds reduces the desirable characteristics of barter trade.
• Persistence: calls for a third party that is often accessible and provides the promised action in return. Furthermore, trust intensive roles are delegated to such a third party, in order to maintain anonymity of the principal and agent.
• Currently, the lack of a decentralized, scalable, low-overhead digital cash system hampers uptake of economic models.
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The importance of trustThe importance of trust
• Risks and threats in P2P– Gnutella Example– No trusted third parties
• Main security techniques without trusted third parties– Micropayments– Reputation based trust systems - building trust through
social control
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Trust Establishing MechanismsTrust Establishing Mechanisms
securitymechanisms
institutional
inte
rper
sonal
hierarchicalCA’s
P2P reputationmechanisms
reputationmechanisms
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Taxonomy of reputationTaxonomy of reputation
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Trust DefinitionsTrust Definitions[McKnight et al.]• Trusting belief is the extent to which a peer
believes that another peer is trustworthy in this situation.
• Trustworthy means one is willing and able to act in the other entity’s best interest.– Consistency, Willingness, Competency, and Honesty
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Reputation Systems Reputation Systems -- ChallengesChallenges• Effective trust model
– Accurately and Effectively capture the trustworthiness of peers– Ability to cope with malicious behaviors of peers– Ability to adapt to different communities and situations
• Implementation– Decentralized implementation– Secure implementation
• Experimental evaluation
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Reputation Mechanism DesignReputation Mechanism Design
ReputationMechanism
Trusting Agent
Trusted AgentMechanism Designer
Value of ReputationSemantics of Reputation &Protocol Implementation
Reputation Information &Reputation Reports
Reputation Information &Reputation Reports
RULES
Trust DecisionMaximize the gain of the Trusting Agent given the available data (i.e. the REPUTATION):
- scale the value of the transaction
- decide whether or not to trade
Reputation has a direct influence on future gains.
Value of R: How much more can a Trusted Agent gain by starting with reputation R?
Value for a negative or positive feedback report!
INCENTIVE COMPATIBLE
COLLUSION RESISTENCE
SCALABLE
RELIABLE
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Other research topicsOther research topics• P2P topology construction, considering several factors:
like peer locality in underlying infrastructure, peer semantic interest, peer capacity, etc.
• Generally, there exist two classes of P2P overlay networks: unstructured and structured. – Features of unstructured P2P: effective for locating highly replicated
items and are resilient to peers joining and leaving the system, but they are poorly suited for locating rare items, and not scalable
– Features of structured P2P: can efficiently locate rare items since the key-based routing is scalable, they incur significantly higher overheads than unstructured P2P networks for popular content, and they do not provide efficient fuzzy keyword based search (semantic-based search)
• the integration of the merits of unstructured and structured P2Pbased on the virtual region to maintain the tradeoff between maintenance cost and search cost.
• P2P application carried on the MANET: the cross-layer design principle, that is the interaction between P2P application layerand MANET network layer.
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Possible innovationsPossible innovations• This research adopts multidisciplinary principles
to design and evaluate incentive-compatible P2P topology formation and adaptation mechanism, incentive mechanisms used to solve or alleviate the impact of freerideing and whitewashing attack, and investigate the QoS in whole system, as the result of local interaction among peers.
• Base on the viewpoint that wireless sensor network can be regarded as specific P2P application carried on MANET, this research attempts to apply P2P distinguished features and incentive mechanisms to sensor network, and improve its efficiency.
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ConclusionConclusion