Sorcery: Could We Make P2P Content Sharing Systems Robust to Deceivers? Ennan Zhai, Ruichuan Chen, Zhuhua Cai, Long Zhang, Eng Keong Lua*, Huiping Sun, Sihan Qing, Liyong Tang, and Zhong Chen (Email: [email protected])

Peking University & *Carnegie Mellon University

Background

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What is the deceptive behavior in P2P content sharing systems ?

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What is the existing solutions on this problem ?

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Our approach ?

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Background

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What is the deceptive behavior in P2P content sharing systems ?

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What is the existing solutions on this problem ?

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Our approach ?

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Deceptive Behavior

Individual or collusive attackers (deceivers) publish some polluted content items, and cast incorrect votes on them … …

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Deceptive Behavior

Individual or collusive attackers (deceivers) publish some polluted content items, and cast incorrect votes on them … …

Normal users are deceived by votes and download these polluted content items.

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Deceptive Behavior Alice’s Content items

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I would like to download File 4.

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Alice’s Votes 1

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Bob 7

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Deceptive Behavior

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However, after downloading content 4, Bob finds this content item is polluted. We say Bob is deceived by Alice’s vote.

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Bob

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Background

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What is the deceptive behavior in P2P content sharing systems ?

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What is the existing solutions on this problem ?

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Our approach ?

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Existing Solutions • Reputation Models: 9 Peer-based: EigenTrust, PeerTrust, Scrubber … 9 Object-based: Credence, FileTrust … 9 Hybrid: XRep, X2Rep, Extended Scrubber…

• Micropayment Techniques: MojoNation. • Exchange Protocol …………

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Existing Solutions • Reputation Models: 9 Peer-based: EigenTrust, PeerTrust, Scrubber … 9 Object-based: Credence, FileTrust … 9 Hybrid: XRep, X2Rep, Extended Scrubber…

• Micropayment Techniques: MojoNation. • Exchange Protocol …………

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Some Problems! Ennan Zhai

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Background

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What is the deceptive behavior in P2P content sharing systems ?

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What is the existing solutions on this problem ?

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Our approach ?

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Sorcery 1

Introducing Social Network

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Challenge-response Mechanism

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Punishment Mechanism

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Practical Issues

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Sorcery 1

Introducing Social Network

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Challenge-response Mechanism

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Punishment Mechanism

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Practical Issues

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Introducing Social Network

Sorcery client stores friends’ information in his friend list. This friend list is confidential to other users in the system … …

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Introducing Social Network

Sorcery client stores friends’ information in his friend list. This friend list is confidential to other users in the system … …

This is the dominant information for the client

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Introducing Social Network Eve

Alice

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Bob

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Eve is Alice’s friend, but Bob cannot know the friend-relationship between Alice and Eve. IEEE P2P 2009

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Introducing Social Network Because friends’ experiences can be used, social network can address cold start problem which cannot be solved by the existing reputation models … …

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Introducing Social Network Because friends’ experiences can be used, social network can address cold start problem which cannot be solved by the existing reputation models … …

New user joins in the system, he is easy to be deceived due to lack of experiences.

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Sorcery 1

Introducing Social Network

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Challenge-response Mechanism

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Punishment Mechanism

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Practical Issues

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Challenge-response

Alice’s Friend list Friend1

Friend2

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Friend4

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Alice 1

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Friend3 2

Bob 2

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6 5

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Eve

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Challenge-response ChallengeMessage

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Alice’s Friend list Friend1

Friend2

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Friend3

Friend4

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Bob Alice 1

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(File5,?),(File3,?),(File2,?)

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Step 1

ChallengeMessage (File3,?),(File8,?),(File4,?)

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Eve 2

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Challenge-response ChallengeMessage

Step 1

Alice’s Friend list Friend1

Friend2

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Friend3

Friend4

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Bob Alice 1

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(File5,?),(File3,?),(File2,?)

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ChallengeMessage (File5,-1),(File3,+1),(File2,+1)

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Step 2

ChallengeMessage

(File3,-1),(File8,-1),(File4,-1)

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Eve

(File3,?),(File8,?),(File4,?)

ChallengeMessage

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Step 2

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Sorcery 1

Introducing Social Network

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Challenge-response Mechanism

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Punishment Mechanism

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Practical Issues

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Punishment Mechanism

Sorcery introduces approach to punish deceivers, thus reducing the possibility of impact brought by them … …

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Punishment Mechanism max(-1, RDi(j) - pn2) RDi(j)= min(1, RDi(j) + r)

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Punishment Mechanism max(-1, RDi(j) - pn2) RDi(j)= min(1, RDi(j) + r)

If j is a deceiver … …

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Punishment Mechanism max(-1, RDi(j) - pn2) RDi(j)= min(1, RDi(j) + r) If j is not a deceiver, and i would like to upgrade RDi(j) … …

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Sorcery 1

Introducing Social Network

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Challenge-response Mechanism

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Punishment Mechanism

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Practical Issues

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Practical Issues

• Lack of the Overlapping Votes • Unreliable Friends

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Practical Issues

• Lack of the Overlapping Votes • Unreliable Friends

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Non-overlapping Voting Histories

The studies in [J. Liang, INFOCOM’05] and [K. Walsh, NSDI’06] indicated it’s a high probability that most peers have overlapping votes with the voters of any content item … …

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Non-overlapping Voting Histories

The studies in [J. Liang, INFOCOM’05] and [K. Walsh, NSDI’06] indicated it’s a high probability that most peers have overlapping votes with the voters of any content item … … The client should challenge some of voters of the target content item (Details see paper please).

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Practical Issues

• Lack of the Overlapping Votes • Unreliable Friends

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Unreliable Friends

In the practical applications, some friends may be online deceivers or compromised, Sorcery utilizes similarity based on cosine technique to filter those unreliable friends (The concrete equation see paper please) … …

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Evaluation

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Simulation Setup

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Experimental Results

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Evaluation

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Simulation Setup

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Experimental Results

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Simulation Setup • Network Model: Gnutella Prototype • Peer Model: 5, 000 Peers • Social Model: Kleinberg Model • Content Model: ¾ 1,000 title, 500 Versions (50 good) ¾ Zipf Distribution a=0.8

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Evaluation

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Simulation Setup

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Experimental Results

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Normal Deceivers

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Normal Deceivers

Rate of Deceivers

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Normal Deceivers

Rate of Deceivers

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Normal Deceivers

Rate of Deceivers

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Tricky Deceivers

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Tricky Deceivers Rate that Tricky Deceivers Vote Correctly

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Tricky Deceivers Rate that Tricky Deceivers Vote Correctly

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Conclusion and Discussion

• How to resist three types of attacks? ¾ Man-in-the-Middle (MITM) Attack ¾ Sybil Attack ¾ Denial-of-Service (DoS) Attack

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Q&A

Thank you !

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