On the Tradeoff between Trust and Privacy in Wireless Ad Hoc Networks
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On the Tradeoff between Trust and Privacy in Wireless Ad Hoc Networks Maxim…...….Raya Reza…….….Shokri Jean-Pierre..Hubaux LCA1, EPFL, Switzerland The Third ACM Conference on Wireless Network Security (WiSec‘10) March 2010 Hoboken, NJ, USA
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On the Tradeoff between Trust and Privacy in Wireless Ad Hoc Networks. Maxim …...…. Raya Reza …….…. Shokri Jean-Pierre .. Hubaux LCA1, EPFL, Switzerland The Third ACM Conference on Wireless Network Security (WiSec‘10) March 2010 Hoboken, NJ, USA . The Trust-Privacy Tradeoff. - PowerPoint PPT Presentation
Transcript of On the Tradeoff between Trust and Privacy in Wireless Ad Hoc Networks
On the Tradeoff betweenTrust and Privacy
in Wireless Ad Hoc NetworksMaxim…...….RayaReza…….….ShokriJean-Pierre..Hubaux
LCA1, EPFL, Switzerland
The Third ACM Conference on Wireless Network Security (WiSec‘10) March 2010 Hoboken, NJ, USA
The Trust-Privacy Tradeoff
Entity-centric trust• Trust is built in each entity
• The cost is reduced privacy
Data-centric trust• Trust is built in the data
• Entities can keep privacy
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priva
cyse
curit
y
securityprivacy
The Dilemma of Data-Centric Trust
• Data increasingly comes from multiple sources
• Mobile devices reflect their users’ preferences and hence characterize them
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Ephemeral network
Users are not fully hidden behind their data!
More contributions = More accurate trust
The Privacy-Preserving Gene
• Building data-centric trust is a collective effort• Users might lose some of their privacy• What if entities are privacy-preserving?• A privacy-preserving entity maximizes its privacy• Game theory: A selfish entity optimizes its utility• Privacy-preservation = Selfishness
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How to build data-centric trust in ephemeral networks with privacy-preserving entities?
Example: VANET• CA pre-establishes
credentials offline• Entities communicate
attributes (e.g., credentials, location)
• Communication is sequential
• There are deadlines on making decisions
• Benign entities disseminate truthful info
• Adversaries disseminate false info
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Trust-Privacy Games• Problem: privacy-preserving entities building data-centric
trust in the presence of privacy-preserving attackers• Game theory can help by modeling situations where the
decisions of players affect each other
• Attacker-Defender Game GAD
• Trust Contribution Game GTC
• Similar to eBay auctions: privacy = money.• But, privacy cannot be «reimbursed»
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A D
Minimum required trust threshold
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Time ……
A D
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A D
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Time ……
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Winner
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A D
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Time
Attacker-Defender Game: captures at the macroscopic level the competition between attackers and defenders to support their respective versions of the truth
ADG
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A D
Start
Deadline
Time
TCG
ADG
Trust Contribution Game: defines at the microscopic level the individual amounts of privacy to be contributed by entities in each side to collectively win GAD
Attacker-Defender Game
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Access to channel is probabilistic
Theorem: The strategy (W,W) is the Perfect Bayesian Equilibrium of GAD
• Players– Attackers– Defenders
• Strategies– Wait (W)– Send (S)
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Deadline
Trust Contribution Game
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Theorem: The Subgame Perfect Equilibrium of GTC is defined by:
* 0kt
No entity contributes!
Game with Incentives
13re
war
d fo
r pla
ying
ear
ly
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Theorem: The equilibrium of is defined by:
K: # of users
ITCG
*2
( 1)k
r KtK
Corollary: The strategy (S,S) can be enforced in GAD by choosing appropriate reward r. I
Incentives help
Conclusion
• Data-centric trust can reduce privacy losses compared to entity-centric trust
• Privacy-preserving entities are selfish by definition and need a game-theoretic analysis
• Without incentives, privacy-preserving entities do not contribute to trust establishment
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