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Sonia Jahid, Prateek Mittal, Nikita Borisov University of Illinois at Urbana-Champaign Presented by Nikita Borisov ASIACCS 2011. EASiER: Encryption-based Access Control in Social Networks with Efficient Revocation. Motivation. Encryption. Encrypt social network data - PowerPoint PPT Presentation
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EASiER: Encryption-based Access Control in Social Networks with Efficient Revocation
Sonia Jahid, Prateek Mittal, Nikita BorisovUniversity of Illinois at Urbana-Champaign
Presented by Nikita BorisovASIACCS 2011
Motivation
2
Encryption
Encrypt social network data flyByNight [Lucas&Borisov’08] NOYB [Guha et al.’09] FaceCloak [Luo et al.’09] Persona [Baden et al.’09]
Users directly control access Grant access by distributing keys Revoke access by…?
3
Revocation
4
Alice
Bob Carol Diana
Existing Data
Expensive!
Our Contribution:Efficient revocation without rekeying or
re-encryption, by using a minimally trusted proxy
Re-encrypt
System Architecture
5
Bob Carol Diana
KeyProxy (Revoke Bob)
Proxy
Modified CTcomponent
CTcomponent
PK, MK
1 AND Colleague
Neighbor
OR
Friend
friend, neighbor
colleague friend,colleague
Alice
SetupKeyGenEncryptRevoke/KeyProxyConvertDecrypt
Algorithms - Basic Idea(cf. [Naor&Pinkas’00])
6
SKr,r
1
SKr,r
2
SKr,r
3
SKr,r
4
CT CT’
SK
Convert
Point to Determine, P(0)
Security
Immediate revocation As soon as proxy updated Including past data
Minimally trusted proxy Cannot decrypt data Cannot “unrevoke” users even if
compromised
7
Evaluation
8
Encrypt Decrypt Keygen0123456789
CP-ABECP-ABE-MNTEASiER
Evaluation- Proxy Rekey
9
0 100 200 300 400 50000.20.40.60.8
11.21.4
Users Revoked
Tim
e to
Rek
ey P
roxy
(s
econ
d)
Comparison
Conventional revocation Rekey 500 friends: 5s Decrypt 2000 items: 13s Encrypt 2000 items: 36s
EASiER: 1.5s
10
Evaluation - Conversion
11
0 20 40 60 80 100
00.20.40.60.8
11.21.4
Leaf Nodes in Policy
Conv
ersio
n TI
me
(sec
ond)
Conclusion We introduced an
efficient revocation scheme for ABE Useful in OSNs Potential uses in other
ABE deployments Open problems
Forward security of proxy
Stronger security proofs
12
Sonia Jahid
Prateek Mittal
Questions?
13
Sonia Jahid
Prateek Mittal