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Volgenau School of Engineering

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Volgenau School of Engineering

LeveragingBlockchain-basedprotocolsinIoT systems

Angelos Stavrou

TalkOutline

• OverviewofIoT

• SecurityFailuresinIoT:MotivatingUseCases

• WhydirectuseofBlockchain isnotpracticalforIoT

• Challenge:DesignpracticalBlockchain-basedprotocolsforIoT

• Conclusions,Discussion&Challenges

2

InternetofThingsDefined

• KevinAshtonintroducedthetermInternetofThings(IoT)in1999

• Networkofdevicesabletoconfigurethemselvesautomatically

• Humanisnotthecenterofthesystem

• Motivation:Betterunderstandingoftheenvironmentandresponsetocertainevents.Machinesaredoingbetterinsensing&reportingonconditions

• Fact:ApplicationsoftraditionalInternetaredifferentthantheapplicationsofIoT

3

What is the Fundamental Problem?• Devices operate using non-verified or tested software

- outdated software- custom-made software- software from many vendors- modular software from many different vendors- poorly tested software- software that was designed for a different set ofrequirements

- unpredictable & chaotic software

Cyber Security is not a Design Tenet

ThereisNOIndustryincentivetobuildSecureSystems(SoftwareorHardware)4

WhattheFutureHolds

5

Drivables Flyables

Scannables Wearables

TheGrowthofIoT

6

SectorsofIoT Applications

Smart Home

Home automation

Energy efficiency

Home security

Transportation

Road safety

Traffic regulation

Law enforcement

Retail

Automatic payments

Efficient cataloguing

Shipment tracking

Industry

Quality assurance

Failure prediction

Productivity improvement

Healthcare

Condition monitoring

Remote treatment

Personalized advices

7

Sensors&Actuators

Sensors Actuators

8

Connectivity

WA

NPA

NLA

N

IPv6

9

TalkOutline

• OverviewofIoT

• SecurityFailuresinIoT:MotivatingUseCases

• WhydirectuseofBlockchain isnotpracticalforIoT

• Challenge:DesignpracticalBlockchain-basedprotocolsforIoT

• Conclusions,Discussion&Challenges

10

CommonSecurityIncidents

90%

Private Data Collection Insecure Interfaces Unencrypted Communications

Weak Requirements

60% 70% 80%

11

Top10Vulnerabilities(OWASP)

Insecure Web InterfacesDefault accounts, XSS, SQL injection

Inefficient Authentication/AuthorizationWeak passwords, no two-factor authentication

Insecure Network ServicesPorts open, use of UPnP, DoS attacks

Lack of Transport EncryptionNo use of TLS, misconfigured TLS, custom encryption

Private DataUnnecessary private information collected

Insecure Cloud InterfacesDefault accounts, no lockout

Inefficient Mobile InterfacesWeak passwords, no two-factor authentication

Insufficient Security ConfigurabilityPorts open, use of UPnP, DoS attacks

Insecure Software/FirmwareOld device firmware, unprotected device updates

Poor Physical SecurityExposed USB ports, administrative accounts

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UseCase:BluetoothLowEnergyBeacons

• Beacons Purpose:– Provide inexpensive remote identification– Proximity estimation– Low power consumption

• BLE modules are integrated with smartphone devices

• Hardware requires very little energy– Easy to maintain and have a small footprint

• Achieve accurate proximity estimation even in indoor scenarios

– Better than GPS

• Identification can be achieved across considerable distances– Better than RFID

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WhatCanGoWrong?• ExistingBLEBeaconspecificationsnaivelyomitprotectioninmessagestructure– Apple’siBeacon,Google’sEddystone,Altbeacon

• VendorsclaimthatBLEBeaconapplicationsarenotsecurity&privacysensitive

• CurrentApplicationscanbeabused– Denialofserviceorlossofrevenue

• Whataboutfutureapplications?– Automaticpayments– AutomaticCheck-In– AuthorizationtoRestrictedAreas– Accesscontroltodevices(e.g.workstation) 14

UnderlyingDesignProblem

• Transmissionofastaticidentifier• Constantbroadcastingofthatidentifier• Longrangetransmissions(75meters)

15

AttackerCapabilities

•Open source software for monitoring– Bluez, Ubertooth, others

•Inexpensive hardware–USB adapter (Sena UD100 Long

Range Bluetooth 4.0 Class1 USB adapter)

–High gain antennas (RP-SMA 2.4GHz 7 DBI)

–Discrete portable devices (e.g. Raspberry Pi)

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Attack:UserProfiling

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Attack:PresenceInference

• Tracking & Reporting the presence of a target within an area

• Target must carry a portable, beacon-emitting object

• Inexpensive equipment can boost the range to more than 300 meters radius • Typical range is 75 meters

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WhynotUseCryptography?

19

RSA1024RuntimeOverhead:

SomeofthetraditionalCryptoistoo“expensive”forembeddeddevices

SurveyofCryptoSupportinIoT

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Brand Name CPU Freq. Sram FlashCryptoAcc. EnergySource

PublicKeyCrypto

Belkin WeMoSwitch RalinkRT5350F(MIPS) 360Hz 32MB 16MB No Wallsocket Yes

Samsung SmarthingsHub

PIC32MX695F-512H 80MHz 128KB 512K No Wallsocket/Battery Yes

Nest ThermostatTIAM3703CUSSitara(ARMCortexA8)

1GHz 512Mb 2Gb Yes Wallsocket Yes

LIFX Color1000 KinetisK22(ARMCortex-M4)

120MHz 128KB 512K No Wallsocket No

Amazon EchoTIDM3725CUS100(ARMCortexA8)

1GHz 256MB 4GB Yes Wallsocket Yes

Philips HueLightsSTMic.STM32F217VE(ARMCortex-M3)

120MHz 128KB 1MB Yes Wallsocket Yes

Philips HueLights(Bulb)

STM32F100RBT6B(ARMCortex-M3)

24MHz 8KB 128KB No Wallsocket No

Nest Smoke/CarbonAlarm

FreescaleSCK60DN512VLL10customKinetisK60

100MHz&48MHz

128KB 512K Yes Wallsocket/Battery Yes

Pebble TimeSTMicroSTM32F439ZG

(ARMCortexM4)180MHz 256KB 2MB Yes Battery No

Adafruit FeatherMOBluefruitLE

TSAMD21G18ARMCortexM0

48MHz 32KB 256KB No Battery No

BeagleBone GreenWireless(othermodels)

AM335x1GHzARMCortex-A8

1GHz512MB

4GBeMMC Yes External/Battery Yes

RaspberryPi Zero ARM1176JZFSArmv6core 1GHz 512MB MicroSD

Yes External/Battery Yes

RaspberryPi Two(2) ARMCortex-A7 900MHz 1GB MicroSD Yes External/Battery YesRaspberryPi Three(3) ARMCortex-A53 1.2GHz 512MB MicroSD Yes External/Battery Yes

Arduino MKR1000(othermodels)

Atmel|SMARTSAMD21Cortex-M0+

32KHz&48MHz

32KB 256KB No Battery No

Fitbit One STMic.32L151C6UltraLowP.ARMCortexM3

32MHz 16KB 128KB No Battery No

Fitbit SurgeSiliconLabsEFM32(ARMCortex-M3)

48MHz 128KB 1MB Yes Battery No

TalkOutline

• OverviewofIoT

• SecurityFailuresinIoT:MotivatingUseCases

• WhydirectuseofBlockchain isnotpracticalforIoT

• Challenge:DesignpracticalBlockchain-basedprotocolsforIoT

• Conclusions,Discussion&Challenges

21

CanweuseBlockchain-inspiredprotocols?

22

• Trust among untrusted Parties• Distributed resilience and control• Fully Decentralized network• Primarily Open source• Security and modern cryptography• Controlled & Open Participation• Smart Contracts• Dynamic and Fluid Operation

Strengths

Whatdowereally need?

23

IoT SystemOperationalRequirements(Empirical)

• Dynamicbutverifiablegroupmembership

• Authentication&Dataintegrity• Secureagainstsingle-node(orsmallsub-setofnodes)keyleakage

• Lightweightoperationsintermsofresources

• Encryptionisaplusbutnotfirmrequirement

• Capableofhandlingsensor“sleep/power-off”periods• Handleresourcediversityanddataofsensorsandaggregators

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PublicDistributedVerifiableCryptographicLeger• Public

• Allparticipantsgainaccessto“read”

• Distributed• Peer-to-PeerDataCommunication,FullyDecentralized

• Cryptographic• Digitallysignedtransactions,proof-of-worklimitsrateofinput

• Ledger• VerifiableTransactionalDatabase

BlockchainPrimer

25

BlockchainPrimer

Blockchain Primer

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Blockchain Blocksv Sequencesofsignedandverifiedtransactionsv Publishedanddistributedgloballyv Magicnumber,Sizev Header

• Hashofpreviousblock(chain)• Merkle roothashofblock• Timestamp• Target,nonce(mining)

v Numberandlistoftransactions

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Blockchain Primer

TalkOutline

• OverviewofIoT

• SecurityFailuresinIoT:MotivatingUseCases

• WhydirectuseofBlockchain isnotpracticalforIoT

• Challenge:DesignpracticalBlockchain-basedprotocolsforIoT

• Conclusions,Discussion&Challenges

28

IsBlockchain DirectlyApplicableinIoT?

29

DesirableProperties• Distributedprotocolwithverifiabletransactionhistory• Dynamicmembershipmulti-partysignatures

UndesirableProperties• Requiresproofof“work”• RequiresPKI• SizeoftheLedgeranissuefor“small”devices• Anonymous(unverifiable)Join/Leaveoperations

Whatcanwedo?

30

Eliminateundesirableproperties• Requiresproofof“work”

Requiresproofofearlierparticipationusinghistory

• RequiresPKIHash-basedsignatures(orotherMerkle-treeschemes)

• SizeoftheLedgeranissuefor“small”devicesPruneandCompressLedger.Maintainonlydevice-relevanttransactionledgerwhendeviceistooresourceconstrained

• Anonymous(unverifiable)Join/LeaveoperationsGroupsignaturesusingpre-sharedgroupKey(s)

Hash-Chains

31

Hash-Chain:PreImage Path

32

Hash-Chain:PreImage Cost

33

But what about in practice?

For sensor nodes and aggregators:

Using Hash chain of size: 232 = 4,294,967,296 passwords • More than 68 years to run out for one (1) transaction per second • Each transaction having a distinct key

IfweselectSHA256asthehashfunctionofchoice:MemoryRequirements:2xlog2(n)+256=320bitsFor32locations+seedtotaling1,320bytesofstorageor1.3KB

TypicalSensorNetworks

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Sensor Sensor Sensor

Aggregator

Sensor Sensor

Aggregator

Sensor

Sensor

Sensor

Aggregator

Aggregator

SensorSensor

Aggregator

Blockchain-basedProtocolforIoT?

35

WesuggestaBlockchain-basedprotocolthatusesthefollowingblocks:

xi = H (Data ||KG ||H (zi )n ),H (zi )

n−1

H = Hash, KG = group Key, zi = sensor i "public key"

36

WesuggestaBlockchain-basedprotocolthatusesthefollowingblocks:

Blockchain-basedProtocolforIoT?

37

• IoT SystemOperationalRequirements(Empirical)• Dynamicbutverifiablegroupmembership• Secureagainstsingle-node(orsmallsub-setofnodes)keyleakage

• OnlyAggregatorscanaddnodesbyissuingagroupKey• CanbedoneusingSymmetricEncryptionoraHashChain• NodeisverifiedbothbygroupkeyANDby participationhistory• Toaddanode,anadversarywillhaveto:

a)Compromisethegroupkeyb)Issuean“addnode”transactionc)Addasensornode

• Shapeofthetreeshows“additions”and“removals”ofnodesovertime

DoestheSchemeMeettheRequirements?

38

• IoT SystemOperationalRequirements(Empirical)• Authentication&Transactionintegrity

• NodesandtransactionsareauthenticatedusingthegroupkeyandthenodeLamport signatures

• AnodeuseshisLamport publickeytovalidateinsertedDATA,transmitsDATAtoaggregator(s)

• Lightweightoperationsintermsofresources• Operationscanbelightweightforsensors.Aggregatorshavemoreresources

• Encryptionisaplusbutnotfirmrequirement• Noneedforencryption

DoestheSchemeMeettheRequirements?

DoestheSchemeMeettheRequirements?

39

• IoT SystemOperationalRequirements(Empirical)• Capableofhandlingsensor“sleep/power-off”periods

• Nodescanre-authenticateusingtheirknowledgeofhistoricaltransactionsprovingtheirmembershipspecifichistoricaltransactionsusingpredecessors forLamport Signatures

• Handleresourcediversityanddataofsensorsandaggregators• Differentnodesstoredifferentportionsoftheledger• Aggregatorsfully,otherspartial

TalkOutline

• OverviewofIoT

• SecurityFailuresinIoT:MotivatingUseCases

• WhydirectuseofBlockchain isnotpracticalforIoT

• Challenge:DesignpracticalBlockchain-basedprotocolsforIoT

• Conclusions,Discussion&Challenges

40

Conclusions

• IoT Scale,Vendors,Technologiesincreaseexponentially• IoT Deviceswillalwayshavediversecapabilities&Resources• UseofCryptographyisdonewithoutclearunderstandingoftheimplications

• NoCurrentStandardsforLightweightcryptography

• Blockchain inspiredprotocolscombinedwithnewCryptographicprimitivesmightbethepathforward

41

Discussion

NowthatwebuildaBlockchain forIoT whatisnext?

• SecureSoftwareUpdatesandTransactionalCross-IoT• Audit&MonitorDevicesfromdifferentVendors• EnableApplicationMarketsforIoT• ShareinformationusingBlockchain SmartContracts• VerifiedTimeforIoT

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AreweDone?Challenges

43

CostofDeployment&EnergyisanopenproblemforIoTdevices,Consumerproducts

Bi-directonality ofcommunicationsScalinglatencyNomsec ornsectransactionsTimeVerification

Privacy&SecurityisnotjustimmutabilityWhataboutdataprovenanceandremoval?Blockchain isforever

Competingtechnologiesarecausingconfusionanddonotoffercompletesolutionsforuserneeds

LackofStandardsandmaturityoftechnologiesanimpedimentforadoption

NovelBlockchain-inspireddesignsthatadheretorequirementsoftheusecases

Scalability&InteroperabilitynotinitialdesigntenetsCommunicationOverhead

Thankyou,Questions?

OperationalTransactions

45