Content Search for Business Using Solr: Presented by Wei Zhao, Box
1 Privacy-Preserving Distributed Information Sharing Nan Zhang and Wei Zhao Texas A&M University,...
-
Upload
thomasina-aileen-willis -
Category
Documents
-
view
217 -
download
1
Transcript of 1 Privacy-Preserving Distributed Information Sharing Nan Zhang and Wei Zhao Texas A&M University,...
1
Privacy-Preserving Distributed Information Sharing
Nan Zhang and Wei Zhao
Texas A&M University, USA
2
Outline
• Motivation
• Dealing with malicious adversaries
• Existing and new protocols
• Conclusion
4
Example
• Supplier– Product list
• Consumer– Shopping list
Secret Weapon I
Secret Weapon V
Dream Machine
Cancer Medicine
Perpetual Machine
…
Secret Weapon I
Secret Weapon II
Secret Weapon III
Secret Weapon IV
Secret Weapon V
…
Secret Weapon I
Secret Weapon V
…
ContractSECRETSECRETSECRETSECRET
5
Privacy Concern
[www.privacy.org, 2002]
• Privacy lawsCountries with enacted or pending omnibus privacy laws
HIPAA
Health Insurance Portability and Accountability Act
6
Privacy-Preserving Information Sharing
• Sharing information across private databases without violating each party’s privacy.
7
Objectives
• To ensure accuracy of information sharing results
• To guarantee privacy of each party
How do we measure accuracy and privacy?
8
Measurement of Accuracy
• Traditional measure of accuracy1, if all parties obtain correct information sharing results
0, otherwise
• We measure accuracy by the expected value of traditional measure– Probability that all parties obtain correct
information sharing results
fails
la1–la accomplishes0 1
9
Measurement of Privacy Disclosure
• Traditional measure in Cryptography0, if no privacy disclosure
1, otherwise
• Our measure in information sharing– Percentage of private
information compromised
undisclosed
lp1–lp disclosed
0 1
12
Local ProcessingModule
DatabaseINTERN
ET
External Attacks
Defense against these attacks can occur by using traditional system security measures
14
INTERNET
Semi-honest AdversariesPrivate informationof the other party
• Properly follow the protocol• Record intermediate computation and communication• Passive attack
• Properly follow the protocol• Record intermediate computation and communication• Passive attack
15
Protocols Against Semi-honest Adversaries
• Almost all existing protocols
• Can be efficient
• Unrealistic assumption: semi-honest
16
INTERNET
Malicious AdversariesPrivate informationof the other party
• Can do whatever it wants• May revise local processing module and/or alter inputs• Active attack
• Can do whatever it wants• May revise local processing module and/or alter inputs• Active attack
17
Protocols Against Malicious Adversaries
• A few protocols exist, with sporadic restrictions
• Inefficient
20
Our Approach IGeneralization of privacy & accuracy measures
• Continuous accuracy measure
• Continuous privacy measure
undisclosed
lp1–lp disclosed
RECALL
fails
la1–la accomplishes
RECALL
22
Outline
• Motivation
• Dealing with malicious adversaries
• Existing and new protocols
• Conclusion
23
Classification of Adversaries
• Priority of Adversary– To obtain the privacy of other parties– To accomplish information sharing
24
Consumer needs Secret Weapon IVPRIVACY
BREACHPRIVACY
BREACH
Secret Weapon I
Secret Weapon V
Dream Machine
Cancer Medicine
Perpetual Machine
…
Adversaries that Care About Information Sharing
• Supplier– Product list
• Consumer– Shopping list
Secret Weapon IV
Secret Weapon I
Secret Weapon V
… Secret Weapon IV
Secret Weapon I
Secret Weapon II
Secret Weapon III
Secret Weapon IV
Secret Weapon V
…
25
Secret Weapon I
Secret Weapon II
Secret Weapon III
Secret Weapon IV
Secret Weapon V
…
Secret Weapon I
Secret Weapon V
Dream Machine
Cancer Medicine
Perpetual Machine
…
Adversaries that Care About Information Sharing
• Supplier– Product list
• Consumer– Shopping list
Secret Weapon IV
Secret Weapon I
Secret Weapon V
… Secret Weapon IV
Secret Weapon I
Secret Weapon V
… Secret Weapon IV
An adversary may be penalized if some parties cannot obtain the accurate information sharing results.
26
Priority of AdversaryP
rior
ity
of a
dver
sary
Information sharing as the first priority
Privacy intrusion as the first priority
27
Measure of Adversary’s Priority
• Priority is measured by , such that the goal of the adversary is to maximize
u = (1 – )la + lp.
la : {0,1}, probability that all parties obtain correct information sharing results
lp : [0,1], percentage of other parties’ private information that is compromised by the adversary.
28
Classification of Malicious Adversaries by Their Priority
Pri
orit
y of
adv
ersa
ry
Weakly malicious
Strongly malicious
Honest = 0
0 < < 1/2
1/2 1
u = (1 – )la + lp
Information sharing as the first priority
Privacy intrusion as the first priority
30
Outline
• Problem definition
• Dealing with malicious adversaries
• Existing and new protocols
• Conclusion
31
Protocol DEDouble Encryption
• Existing Protocol [R. Agrawal et. al, 2003]
• For intersection of two datasets
• Basic idea:
aa
BA AB
32
Protocol DE
Bob
• Input: Datasets A, B. Output: A B.
Alice
A:8 B:10
AAA AABAAB AAA
AABAAA
ABAB
AB
AABAAAAABAAB
SameorderSameorder
33
Protocol TPSTrust Party with the Smallest Dataset
• Our New Protocol I
• Basic Idea:
Size: 8 Size: 10
TRUSTTRUST
34
Assumptions
• The distribution of the number of data points of each party is known by all parties
• For the sake of simplicity, we assume that both parties have the same distribution
35
Bob
Protocol TPS
• Input: Datasets A, B. Output: A B.
8Alice
A:8
10
10 8
B:10
10 8
AAA AABAAB AAA
AABAAA
ABAB
AB
AABAAAAABAAB
36
Protocol RPLReject Parties with the Too Large Dataset
• Our New Protocol II
• Basic Idea:
Reject parties whosedatasets are larger thana threshold set by thehonest parties
37
Protocol RPL
Bob
• Input: Datasets A, B. Output: A B.
Alice
A:8 B:10
10 8
AAA AAB
AAB
AAAAAAAABAAB
AAAB
ABAB
AB
AAA
AAAAAA AABAAB
Is 10 too large?Is 10 too large? Is 8 too large?Is 8 too large?
38
Performance: Efficiency
DE
4|V0|
TPS RPL
3|V0|
2|V0|
Lower bound tobe secure againstsemi-honestadversaries
Lower bound tobe secure againstweakly maliciousadversaries
Com
mun
icat
ion
Ove
rhea
d
39
Performance: Defense Against Weakly Malicious Adversaries
Protocol DE
Protocol RPL
Protocol TPS
DE
100
80
60
40
20
0TPS RPL
l a(s
A,
s D0)
(%)
102
100
80
60
40
20
0
|V|
l p(s
A,
s D0)
(%)
102.3 102.6 102.9 103.2 103.5
Privacy Disclosure
AccuracyPercentage of datacompromised bythe adversary
Percentage of datacompromised bythe adversary
Probability that allparties obtain accurateinformation sharing results
Probability that allparties obtain accurateinformation sharing results
40
Defense Against Strongly Malicious Adversaries
Performance Evaluation
Protocol DEProtocol TPSProtocol RPL when = 10Protocol RPL when = 2Protocol RPL when 1
102
100
80
60
40
20
0
|V|
l p(s
A,
s D0)
(%)
102.3 102.6 102.9 103.2 103.5
Privacy Disclosure
DE
100
80
60
40
20
0TPS RPL
l a(s
A,
s D0)
(%)
AccuracySystem parameterPenalty / Benefit onPrivacy intrusion attack
System parameterPenalty / Benefit onPrivacy intrusion attack
41
Outline
• Problem definition
• Dealing with malicious adversaries
• Existing and new protocols
• Conclusion
42
Final Remarks
• Simple and efficient protocols exist if we– Adopt the continuous measure of privacy
disclosure– Constrain the adversary goal to be weakly
malicious
• Future work– Additional set operation protocols– Multiple correlated attacks
45
Weakly and Strongly MaliciousP
rior
ity
of a
dver
sary
Weakly malicious
Strongly malicious
Honest = 0
0 < < 1/2
1/2 1
u = (1 – )la + lp
Information sharing as first priority
Privacy intrusion as first priority
If successful intrusion failed information sharingthen the adversary will not perform the intrusionIf successful intrusion failed information sharingthen the adversary will not perform the intrusion
47
• Goal of adversary: Maximize
u = (1 – )la + lp .
• Weakly malicious means < 1/2.
• The optimal strategy for weakly malicious adversaries (sA) is to alter its dataset by
V1′s.t. V1 V1′
Defense Against Weakly Malicious Adversaries
Methodology
RECALL
RECALL
If successful intrusion failed information sharingthen the adversary will not perform the intrusionIf successful intrusion failed information sharingthen the adversary will not perform the intrusion
48
Basic Idea of Defense Against Weakly Malicious Adversaries
• Give them a dilemma
Weakly Malicious
If successful intrusion failed information sharingthen the adversary will not perform the intrusionIf successful intrusion failed information sharingthen the adversary will not perform the intrusion
No intrusionSuccessful Information SharingNo intrusionSuccessful Information Sharing
IntrusionFailed Information SharingIntrusionFailed Information Sharing
?
RECALLRECALL
49
Defense AgainstStrongly Malicious Adversaries
• We have to sacrifice some honest parties.– Because we cannot distinguish them from
strongly malicious adversaries.Alice
Eve
… Justin
Alice
Eve
… Justin
Strongly Malicious Honest
?
50
• When an honest party takes the strategy (sD
0) to strictly follow the protocol, there is
lp (sA, sD0) Pr{vV0 | vV}/|V|
Privacy Disclosure w/Weakly Malicious Adversaries
51
Defense Against Strongly Malicious Adversaries
Methodology
• Nash Equilibrium– A pair of attack strategy and defensive strategy
{sA, sD} such that
– Thus, we can consider {sA, sD} as the set of strategies taken by rational parties
Whoever moves from the strategy pays the penaltyWhoever moves from the strategy pays the penalty
52
Strategies
Honest
Low privacy, high accuracy
Low accuracy, high privacy
Strongly MaliciousHigh risk, high payoff
Low risk, low payoff
Large V1′
Small V1′
Large tolerable V1′
low tolerable V1′