KeyDistribution-SouthernMethodistUniversity-World密钥分配-南卫理公会大学-世界

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1、KeyDistributionSMUCSE5349/7349WheretoPutEncryption?LinklevelVulnerablelinksequippedwithencryptiondevicesonbothsidesNeedslargenumberofdevicesNeedsdecryptiontoperformroutingEnd-to-endCarriedoutattheendsystemsCanencryptonlythedataportionandnottheheaderSMUCSE5349/7349Linkvs.End-to

2、-EndKeyDistributionLinkkeysmustbedistributedtoeachpairoflinkendpointsinadvanceRelativelyeasytodistributesecurelyFore-t-e,mustgenerateanddistributemanykeys,ofteninrealtimeSMUCSE5349/7349LogicalPlacementApplicationlayerTransportlayerNetworklayerLinklayerSMUCSE5349/7349TrafficAna

3、lysisBothtechniqueshideuserdata(payload)LinkencryptionHidesaddressinformationBufferscleardataineachnodeE-T-EencryptionLeavesaddressesintheclearNoneedtobufferdecryptedpayloadUsebothtechniques?SMUCSE5349/7349TrafficAnalysisIdentitiesofcommunicatingpartnersFrequencyofcommunicatio

4、nMessagepatterns,e.g.,length,quantity,(encrypted)contentCorrelationbetweenmessagesandrealworldeventsCan(sometimes)bedefeatedthroughtrafficpaddingSMUCSE5349/7349CovertChannelsEssentially,thedualoftrafficanalysisUsuallyintendedtoviolateordefeatasecuritypolicyExamplesMessagelengt

5、hMessagecontentMessagepresenceSMUCSE5349/7349KeyDistributionMostimportantcomponentinsecuretransmission.Options:(betweenAandB).AselectsakeyandphysicallydeliversittoB.Atrustedthirdpartykeydistributioncenter(KDC)selectsakeyandphysicallydeliversittoAandB.IfAandBalreadyhavehaveavia

6、blekey,itcanbeusedtodistributeanewkey.IfAandBhaveasecurelinktoKDC,canreceivethekeythroughthatchannel.SMUCSE5349/7349KeyDistribution(cont’d)Manualdeliveryisstraightforwardforlinkencryption,challengingforE-T-EThenumberofkeysgrowsquadraticallywiththenumberofendpoints(n*(n-1)/2)Fu

7、rthercomplexityforapplication/userlevelencryptionKDCagoodalternativeOnlynmasterkeysrequiredSMUCSE5349/7349DecentralizedDistributionNoneedforKDCtobetrustedandprotectedAnytwonodescanestablishasessionkeyNeedsn(n-1)/2masterkeysCangenerateanynumberofsessionkeysKeydistributionprotoc

8、olSMUCSE5349/7349PublicKeyManagementDistributionofpublickeysP