ALPTEKN KPAssistant Professor of Computer Science and Engineering

Ph.D., Brown University (2004-2010)Asst. Prof., Ko University (2010- )

General

Cryptographic protocols can efficiently and scalably be used to

provide security and privacy for the next generation cloud systems.

2012 Alptekin Kp - Ko University 2

Cryptography Security Privacy

Core Research

Application Areas Cloud Computation Cloud Storage Peer-to-Peer Systems Electronic Cash Electronic ID Cards Password-based Authentication ...

Research Topics

2012 Alptekin Kp - Ko University 3

Challenges:Outsource a job to a more powerful entity, or multiple small entities, and get correct results, without wasting own resources.

Obje, grsel, tablo, grafik alan

Cloud Computation

Current Generation:Amazon Mechanical Turk, SETI@Home, etc.Job is not well-defined.Results can be faked.No provable guarantees.

Techniques:Game Theory and Mechanism Design, augmented with cryptographic techniques to deal with Byzantine users.

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[BCEJKL08]

Our Solutions:Guaranteed high fraction of correctresults, even in presence of malicious users.Malicious users cannot force the boss to perform tons of extra work.

Obje, grsel, tablo, grafik alan

Next Gen Cloud Computation

rewardfine

[BCEJKL08]

2012 Alptekin Kp - Ko University 5

Challenges:Outsource storage of data to a more powerful entity, or multiple small entities, while data will be kept intact, or you will get compensated.

Obje, grsel, tablo, grafik alan

Cloud Storage

Current Generation:Amazon S3, Google Drive, Dropbox, etc.No guarantee that file will be kept intact (i.e. No modifications or deletions).

Techniques:Cryptography, as well as secure protocol design, probability, and error-correcting codes (erasure codes).

2012 Alptekin Kp - Ko University 6

[EKPT09][K12][EK12][CKW12]

Next Gen Cloud Storage[EKPT09]

Our Solutions:Guaranteed high probability detection of integrity loss of data.2012 Alptekin Kp - Ko University 7

Our Solutions:Automated official arbitration system with compensation (via e-cash).

Next Gen Cloud Storage[K12]

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Challenges:Incentivize peers to contribute to the system, thereby increasing overall system performance and fault tolerance.

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Peer-to-Peer Systems

Techniques:Cryptography (fair exchange protocols and electronic cash), together with economic analysis and game-theoretic models.

Our Solutions:Forced fair contribution by peers both increase the fault tolerance of the system, as well as increased performance.

[BCEJKLR07][KL09][KL10a][KL10b][KL12]

2012 Alptekin Kp - Ko University 9

Applications:Electronic commerce, privacy-protecting protocols, anonymous credentials and electronic identity cards.

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Electronic Cash

Use Cases:Cryptographic protocol design, virtual economies, automated payments, and even official arbitration mechanisms.

Future Uses:Accountability issues can be handled through e-cash while preserving privacy (e.g., in GPS, transport, or cloud systems).

[BCEJKLR07][MEKHL10]

2012 Alptekin Kp - Ko University 10

TOPIC RELATEDWORK

OURWORK

CloudStoragenetworkoverhead N/A 10KBCloudStoragecomputationoverhead N/A 1msJudgeArbitrationnetworkoverhead 25KB 80bytesJudgeArbitrationcomputationoverhead 1second 2msP2P Fairnessnetworkoverhead(over2.8GB) 225MB 1.8MBP2P Fairnesscomputationoverhead(over1.5hours) 42minutes 40seconds

2-3 orders of magnitude

2012 Alptekin Kp - Ko University 11

Efficient Cryptography

Other possibilities: Outsourced Databases

Privacy(e.g.,PIR,obfuscation)

Usable Security PasswordbasedAuthenticationandOTP

Peer-to-Peer Systems Fair(video)streaming

Anonymous Credentials (and E-cash) ElectronicIDandPassport

Electronic Health PrivacypreservingInformationSharing

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Collaboration Areas

ALPTEKN KPAssistant Professor of Computer Science and Engineering

http://crypto.ku.edu.tr

References[BCEJKLR07]MiraBelenkiy,MelissaChase,ChrisErway,JohnJannotti,Alptekin Kp,AnnaLysyanskaya,andEricRachlin.MakingP2PAccountablewithoutLosingPrivacy.ACMWPES,2007.[BCEJKL08]MiraBelenkiy,MelissaChase,ChrisErway,JohnJannotti,Alptekin Kp,andAnnaLysyanskaya.Incentivizingoutsourcedcomputation.NetEcon,2008.[KL09]Alptekin Kp andAnnaLysyanskaya.BriefAnnouncement:ImpossibilityResultsonOptimisticFairExchangewithMultipleAutonomousArbiters.PODC 2009.FullversionavailableasCryptologyePrint ArchiveReport2009/069.[EKPT09]ChrisErway,Alptekin Kp,Charalampos Papamanthou,andRobertoTamassia.DynamicProvableDataPossession.ACMCCS2009.FullversionavailableasCryptologyePrint ArchiveReport2008/432.[KL10a]Alptekin Kp andAnnaLysyanskaya.UsableOptimisticFairExchange.CTRSA 2010.FullversionavailableasCryptologyePrint ArchiveReport2008/431.[KL10b]Alptekin Kp andAnnaLysyanskaya.OptimisticFairExchangewithMultipleArbiters.ESORICS,2010.[MEKHL10]SarahMeiklejohn,ChrisErway,Alptekin Kp,TheodoraHinkle,andAnnaLysyanskaya.EnablingEfficientImplementationofZeroKnowledgeProofsandElectronicCashwithZKPDL.USENIXSecurity,2010.[K10]Alptekin Kp.EfficientCryptographyfortheNextGenerationSecureCloud:Protocols,Proofs,andImplementation.LambertAcademicPublishing,2010.[KL12]Alptekin Kp andAnnaLysyanskaya.UsableOptimisticFairExchange.ComputerNetworks,2012,56,5063.[ABK12]Tolga Acar,MiraBelenkiy,andAlptekin Kp.SinglePasswordAuthentication.Undersubmission,2012.[K12]Alptekin Kp.OfficialArbitrationanditsApplicationtoSecureCloudStorage.Undersubmission,2012.[EK12]MohammadEtemad andAlptekin Kp.Transparent,Distributed,andReplicatedDynamicProvableDataPossession.Undersubmission,2012.[CKW12]DavidCash,Alptekin Kp,andDanielWichs.DynamicProofsofRetrievability viaObliviousRAM.Undersubmission,2012.

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