Secure Data Deletion

208 Pages·2016·1.26 MB·English

by  Joel Reardon (auth.)

Information Security and Cryptography
Joel Reardon
Secure Data
Deletion
Information Security and Cryptography
Series editors
David Basin, ETH Zürich, Switzerland
Kenny Paterson, Royal Holloway, University of London, UK
More information about this series at http://www.springer.com/series/4752
Joel Reardon
Secure Data Deletion
123
Joel Reardon
Institute of Information Security
ETHZürich
Zürich
Switzerland
ISSN 1619-7100 ISSN 2197-845X (electronic)
Information Security andCryptography
ISBN978-3-319-28777-5 ISBN978-3-319-28778-2 (eBook)
DOI 10.1007/978-3-319-28778-2
LibraryofCongressControlNumber:2016955922
©SpringerInternationalPublishingSwitzerland2016
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TothewonderfulteachersI’vehad.
Acknowledgments
I would like to acknowledge the contributions of many people to the conception
andcompletionofthisbook.ForemostismydoctoraladvisorsSrd¯anCˇapkunand
DavidBasin,withwhomthecontentsofthisbookwereconceived,conjecturedand
criticized,alongwithadditionalcollaborationwithClaudioMarforio,AlinaOprea,
and Hubert Ritzdorf. Various drafts of chapters and the papers on which they are
basedreceivedhelpfulcommentsfromStevenDropsho,ClemensFruhwirth,Arthur
Gervais,MarcoGuarnieri,AriJuels,NikolaosKarapanos,GregorKasieczka,Kari
Kostiainen, René Kyllingstad, Luka Malisa, Grgur Maretic, Ognjen Maric, Srdjan
Marinovic,RamyaJayaram Masti,ChristinaPöpper,Aanjhan Ranganathan,Clau-
dio Soriente, Alessandro Sorniotti, Nils Ole Tippenhauer, Thomas Themel, Petar
Tsankov,PaulVanOorschot,ThiloWeghorn,andDer-YeuanYu.AbelGroenewolt
improved the aethetics of the figures by commenting on their clarity, consistency,
and symmetry. Ronan Nugent provided great support from Springer in producing
thiswork.IgratefullyacknowledgetheZurichInformationSecurityCenterandthe
SwissNationalScienceFoundationfortheirsupportofthiswork.Finally,Iwould
liketogivemydeepestgratitudetoJoannaBolechowskaaswellasmyfamilyfor
theirloveandsupport.
vii
Contents
PartI IntroductionandBackground
1 Introduction................................................... 3
1.1 OrganizationandStructure................................... 7
2 RelatedWorkonSecureDeletion ................................ 11
2.1 Introduction ............................................... 11
2.2 RelatedWork.............................................. 11
2.2.1 LayersandInterfaces................................. 12
2.2.2 Physical-LayerandController-LayerSanitization ......... 15
2.2.3 User-LevelSolutions ................................. 17
2.2.4 File-System-LevelSolutionswithIn-PlaceUpdates ....... 20
2.2.5 Cross-layerSolutions................................. 22
2.2.6 Summary........................................... 23
2.3 AdversarialModel.......................................... 23
2.3.1 ClassesofAdversarialCapabilities ..................... 23
2.3.2 Summary........................................... 25
2.4 AnalysisofSolutions ....................................... 26
2.4.1 ClassesofEnvironmentalAssumptions.................. 27
2.4.2 ClassesofBehaviouralProperties ...................... 27
2.4.3 Summary........................................... 30
3 SystemModelandSecurityGoal................................. 33
3.1 Introduction ............................................... 33
3.2 SystemModel ............................................. 33
3.3 StorageMediumModels .................................... 34
3.4 AdversarialModel.......................................... 36
3.5 SecurityGoal.............................................. 37
ix
x Contents
PartII SecureDeletionforMobileStorage
4 FlashMemory:BackgroundandRelatedWork.................... 47
4.1 Overview ................................................. 47
4.2 FlashMemory ............................................. 48
4.2.1 In-PlaceUpdatesandLog-StructuredFileSystems ........ 49
4.2.2 FlashTranslationLayer............................... 51
4.2.3 FlashFileSystems ................................... 52
4.2.4 GeneralizationstoOtherMedia ........................ 52
4.3 RelatedWorkforFlashSecureDeletion........................ 52
4.4 Summary ................................................. 55
5 User-LevelSecureDeletiononLog-StructuredFileSystems......... 57
5.1 Introduction ............................................... 57
5.2 SystemandAdversarialModel ............................... 58
5.3 YAFFS ................................................... 58
5.4 DataDeletioninExistingLog-StructuredFileSystems ........... 59
5.4.1 InstrumentedYAFFS ................................. 60
5.4.2 SimulatingLargerStorageMedia....................... 61
5.5 User-SpaceSecureDeletion.................................. 63
5.5.1 Purging ............................................ 64
5.5.2 Ballooning.......................................... 65
5.5.3 HybridSolution:BallooningwithPurging ............... 67
5.6 ExperimentalEvaluation .................................... 67
5.6.1 ExperimentalResults................................. 68
5.7 Summary ................................................. 72
5.8 ResearchQuestions......................................... 72
6 DataNodeEncryptedFileSystem................................ 73
6.1 Introduction ............................................... 73
6.2 SystemandAdversarialModel ............................... 73
6.3 DNEFS’sDesign........................................... 74
6.3.1 KeyStorageArea .................................... 75
6.3.2 Keystore ........................................... 75
6.3.3 ClockedKeystoreImplementation ...................... 77
6.3.4 ClockOperation:KSAUpdate ......................... 79
6.3.5 Key-StateMap ...................................... 79
6.3.6 Summary........................................... 81
6.4 ExtensionsandOptimizations ................................ 81
6.4.1 GranularityTrade-off................................. 81
6.4.2 KSAUpdatePolicies ................................. 83
6.4.3 KSAOrganization ................................... 83
6.4.4 ImprovingReliability................................. 83
6.4.5 EncryptedFileSystem................................ 84
6.5 Summary ................................................. 84
Contents xi
6.6 ResearchQuestions......................................... 85
7 UBIFSec:AddingDNEFStoUBIFS.............................. 87
7.1 Introduction ............................................... 87
7.2 SystemandAdversarialModel ............................... 87
7.3 Background ............................................... 87
7.3.1 MTDandUBILayers ................................ 88
7.3.2 UBIFS ............................................. 88
7.4 UBIFSecDesign ........................................... 90
7.4.1 KeyStorageArea .................................... 90
7.4.2 Key-StateMap ...................................... 92
7.4.3 Summary........................................... 94
7.5 ExperimentalValidation..................................... 94
7.5.1 AndroidImplementation .............................. 96
7.5.2 WearAnalysis....................................... 96
7.5.3 PowerConsumption.................................. 98
7.5.4 ThroughputAnalysis ................................. 98
7.5.5 TimingAnalysis ..................................... 99
7.6 Conclusions ...............................................101
7.7 Practitioner’sNotes.........................................101
PartIII SecureDeletionforRemoteStorage
8 CloudStorage:BackgroundandRelatedWork....................105
8.1 Introduction ...............................................105
8.2 PersistentStorage ..........................................105
8.2.1 SecurelyDeletingandPersistentCombination............106
8.2.2 CloudStorage.......................................106
8.3 RelatedWork..............................................108
8.4 Summary .................................................113
9 SecureDataDeletionfromPersistentMedia.......................115
9.1 Introduction ...............................................115
9.2 SystemandAdversarialModel ...............................116
9.3 GraphTheoryBackground...................................116
9.4 Graph-TheoreticModelofKeyDisclosure .....................118
9.4.1 KeyDisclosureGraph ................................118
9.4.2 SecureDeletion .....................................120
9.5 ShadowingGraphMutations .................................120
9.5.1 MangrovePreservation ...............................123
9.5.2 ShadowingGraphMutationChains .....................125
9.5.3 MangroveKeyDisclosureGraphsinRelatedWork........126
9.6 Summary .................................................127
9.7 ResearchQuestions.........................................128