Security in Wireless Sensor Networks: Key Management ApproachesOverviewSensor NetworksApplicationsSecurity issues in WSNAttacks on WSNFalse routing informationSelective forwardingSinkhole and Sybil attacksWormholesWormholes (cont.)HELLO flood attackAcknowledgment spoofingOverview of CountermeasuresKey management: goalsKey management: constraintsKey management: evaluation/comparison metricsKey management approaches classificationApproaches to be discussedStraight forward approachesBasic probabilistic approachKey pre-distributionShared-key discoveryPath-key establishmentSimulation resultsKey revocationResiliency to node captureWSN connectivityRandom graphsRandom-graphs (cont.)Key ring and key pool sizesKey ring and key pool size (cont.)Key ring and key pool size: exampleq-composite approachBenefits of q-composite approachZhu / Xu approachZhu / Xu approach: key pre-distributionZhu / Xu approach: Logical path establishmentZhu / Xu: pairwise key establishmentFurther enhancementsSmart attackerSlide 44Slide 45PRK algorithmPRK algorithmPRK algorithm analysisPRK algorithm: simulationsBackground: polynomial based key pre-distributionPolynomial based key pre-distribution : initializationPolynomial based key pre-distribution : key discoveryPolynomial based key pre-distribution : examplePolynomial based key pre-distribution : generalizationLiu-Ning approachSetup phaseDirect key establishment phasePath key establishment phaseSlide 59Simulation results: comparison with already discussed approachesGrid-based key pre-distributionSubset assignmentSubset assignment (cont.)Node assignment in the gridPolynomial share discoveryPath discoveryPath discovery: examplePublic key infrastructureSymmetric vs. asymmetric algorithmsPublic key scheme for WSNArbitrated keying protocols: system modelArbitrated keying protocols: node requirementsIdentity based hierarchical keying: initialization phase (description)Identity based hierarchical keying: initialization phase (protocol)Identity based hierarchical keying: node additionIdentity based hierarchical keying: node addition (cont.)Identity based hierarchical keying: node revocationIdentity based hierarchical keying: node revocation (cont)Identity based hierarchical keying: simulationsIdentity based hierarchical keying: analysisLocation Aware Key Management for WSNLocation Aware Purely Random Key Predistribution (P-RKP)Slide 83Slide 84Slide 85Slide 86Slide 87Slide 88Slide 89Slide 90Slide 91Slide 92Slide 93Slide 94Slide 95Slide 96Slide 97Location Aware Structured Key Random Key Predistribution (SK-RKP)Location Aware SK-RKPSlide 100Key Predistribution (I –Scheme) within a given zoneKey Predistribution (E-Scheme) for adjacent zonesSlide 103Key establishment within the same zoneKey establishment within adjacent zonesPerformance AnalysisPerformance Analysis (Security)SummaryBibliographySlide 110Slide 111Security in Wireless Sensor Networks: Key Management ApproachesVasyl A. Radzevych and Sunu MathewOverview•Wireless Sensor Networks (WSN)•Security issues in WSN•Key management approaches in WSN:•Overview•Pre-Deployed Keying•Key pre-deployment•Key derivation information pre-deployment•Location aware pre-deployed keying•Random Key Pre-deployment (P-RKP)•Key derivation information pre-deployment •Autonomous protocols•Pairwise asymmetric (public key)•Arbitrated protocols•Identity based group keying•ConclusionsSensor NetworksSensor network is composed of a large number of sensor nodesSensor nodes are small, low-cost, low-power devices that have following functionality:communicate on short distancessense environmental dataperform limited data processingNetwork usually also contains “sink” node which connects it to the outside worldApplicationsWSN can be used to monitor the conditions of various objects / processes. Some examples:Military: friendly forces monitoring, battlefield surveillance, biological attack detection, targeting, battle damage assessmentEcological: fire detection, flood detection, agricultural usesHealth related: human physiological data monitoringMiscellaneous: car theft detection, inventory control, habitat monitoring, home applicationsSensors are densely deployed either inside or very close to the monitored object / processSecurity issues in WSNThe discussed applications require communication in WSN to be highly secureMain security threats in WSN are:Radio links are insecure – eavesdropping / injecting faulty information is possibleSensor nodes are not temper resistant – if it is compromised attacker obtains all security informationAttacker types:Mote-class: attacker has access to some number of nodes with similar characteristics / laptop-class: attacker has access to more powerful devicesOutside (discussed above) / inside: attacker compromised some number of nodes in the networkAttacks on WSNMain types of attacks on WSN are:spoofed, altered, or replayed routing informationselective forwarding sinkhole attacksybil attackwormholesHELLO flood attacksacknowledgment spoofingFalse routing informationInjecting fake routing control packets into the network, examples: attract / repeal traffic, generate false error messagesConsequences: routing loops, increased latency, decreased lifetime of the network, low reliabilityBA1A3A2A4Example: captured node attracts traffic by advertising shortest path to sink, high battery power, etcSelective forwardingMulti hop paradigm is prevalent in WSNIt is assumed that nodes faithfully forward received messagesCompromised node might refuse to forward packets, however neighbors might start using another routeMore dangerous: compromised node forwards selected packetsSinkhole and Sybil attacksSinkhole attack:Idea: attacker creates metaphorical sinkhole by advertising for example high quality route to a base stationLaptop class attacker can actually provide this kind of route connecting all nodes to real sink and then selectively drop packets Almost all traffic is directed to the fake sinkholeWSN are highly susceptible to this kind of attack because of the communication pattern: most of the traffic is directed towards sink – single point of failureSybil attack:Idea: a single node pretends to be present in different parts of the network. Mostly affects geographical routing protocolsWormholesIdea: tunnel packets received on one part of the network to another Well