Trust Mechanisms in Ad Hoc Networks

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Trust Mechanisms inTrust Mechanisms inAd Hoc NetworksAd Hoc Networks

Azar Rahimi DehaghaniAzar Rahimi DehaghaniLei HuLei Hu

Trust and Security Trust and Security Case Study 2Case Study 2

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OutlineOutline Introduction to ad hoc networksIntroduction to ad hoc networks Security issues in ad hoc Security issues in ad hoc

networksnetworks Existing Security SolutionsExisting Security Solutions Trust modelsTrust models SummarySummary

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Ad Hoc NetworksAd Hoc Networks Characteristics:Characteristics:

– Temporarily formedTemporarily formed– Nodes act as routersNodes act as routers– Infrastructure-lessInfrastructure-less– Limited resources Limited resources – Shared wireless Shared wireless

mediummedium

Applications:Applications:– Military battlefield Military battlefield

networksnetworks– Personal Area Personal Area

Networks Networks – Disaster and rescue Disaster and rescue

operation operation – Peer to peer networksPeer to peer networks

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Ad Hoc NetworksAd Hoc Networks Routing protocols types: Routing protocols types:

– Reactive routing protocolsReactive routing protocols– Proactive routing protocolsProactive routing protocols

Leading protocols:Leading protocols:– DSR: Dynamic Source RoutingDSR: Dynamic Source Routing– AODV: Ad hoc On-demand Distance AODV: Ad hoc On-demand Distance

Vector RoutingVector Routing

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Challenges in Ad Hoc Challenges in Ad Hoc NetworkNetwork The nodes are constantly mobileThe nodes are constantly mobile The protocols implemented are co-The protocols implemented are co-

operative in natureoperative in nature There is a lack of a fixed There is a lack of a fixed

infrastructure to collect audit datainfrastructure to collect audit data No clear distinction between No clear distinction between

normalcy and anomaly in ad hoc normalcy and anomaly in ad hoc networksnetworks

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Attacks on Ad Hoc Attacks on Ad Hoc NetworksNetworks Passive attacksPassive attacks

– Do not change the routing informationDo not change the routing information– Listen to get valuable informationListen to get valuable information

Active attacksActive attacks– Use its energy to manipulate the routing Use its energy to manipulate the routing

informationinformation

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Active AttacksActive Attacks Modification:Modification:

– Malicious node can modify routing Malicious node can modify routing informationinformation

Fabrication: Fabrication: – Generating false routing messageGenerating false routing message

Impersonation: Impersonation: – Initiate attack by masquerading as Initiate attack by masquerading as

another node another node

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Existing Security Existing Security SolutionsSolutions Intrusion preventionIntrusion prevention

– Encryption, authenticationEncryption, authentication Nodes are required to have pre-Nodes are required to have pre-

shared keys or digital certificatesshared keys or digital certificates Central trust authority or pre Central trust authority or pre

configuration is not practical for configuration is not practical for ad-hoc networks ad-hoc networks

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Trust Model 1Trust Model 1 Computes situational trust in agents based Computes situational trust in agents based

upon the general trust in the trustor and upon the general trust in the trustor and the importance of the situation the importance of the situation

1.1. Trust derivation: the information that one node Trust derivation: the information that one node can gather about the other nodes in passive can gather about the other nodes in passive mode mode

2.2. Quantification: model represents trust in a Quantification: model represents trust in a continual range -1 to 1 signifying a continuous continual range -1 to 1 signifying a continuous range from complete distrust to complete trust range from complete distrust to complete trust

3.3. Computation: involves an assignment of Computation: involves an assignment of weights to the events that were monitored and weights to the events that were monitored and quantified quantified

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DSR ProtocolDSR Protocol On demand protocol: route information On demand protocol: route information

discovered only as neededdiscovered only as needed Source routing: entire path to Source routing: entire path to

destination supplied by source in destination supplied by source in packet headerpacket header

Procedure: Procedure: – Route discoveryRoute discovery– Route maintenanceRoute maintenance– RoutingRouting

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Route DiscoveryRoute Discovery Route Request:Route Request:

– Source broadcasts Route Request message Source broadcasts Route Request message for specified destinationfor specified destination

– Intermediate node adds itself to path in Intermediate node adds itself to path in message and forwards message toward message and forwards message toward destinationdestination

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Route DiscoveryRoute Discovery Route Reply:Route Reply:

– Destination unicasts Route Reply Destination unicasts Route Reply message to sourcemessage to source

A ERoute Reply

messageA-B-C-D

MatchNew entry

A ERoute Reply

messageA-B-C-D

MatchNew entry

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Route MaintenanceRoute Maintenance Used when link breakage occursUsed when link breakage occurs

– Link breakage may be detected using link-layer ACKs, Link breakage may be detected using link-layer ACKs, “passive ACKs”, DSR ACK request“passive ACKs”, DSR ACK request

– Route Error message sent to source of message being Route Error message sent to source of message being forwarded when break detectedforwarded when break detected

– Intermediate nodes “eavesdrop”, adjust cached routes Intermediate nodes “eavesdrop”, adjust cached routes – Source deletes route; tries another if one cached, or Source deletes route; tries another if one cached, or

issues new Route Requestissues new Route Request

A B C D E

Route error message: C-D is broken

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DSR Based on Model 1DSR Based on Model 1

Trust derivation: Trust derivation: – AcknowledgementsAcknowledgements– Packet precisionPacket precision– SalvagingSalvaging– Black listsBlack lists

Trust quantification: Trust quantification: – Quantizes the events and assigns weights to themQuantizes the events and assigns weights to them

Trust computation:Trust computation:– Determines aggregate trust level for a particular Determines aggregate trust level for a particular

node node

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Trust Model 2Trust Model 2 Build trust Build trust

manager on each manager on each node in the node in the network network

Two components:Two components:– Monitoring Monitoring

modulemodule– Reputation Reputation

handling modulehandling module

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Monitoring ModuleMonitoring Module Each node independently Each node independently

monitors its neighboring nodes monitors its neighboring nodes packet forwarding activitiespacket forwarding activities

It is related to the proportion of It is related to the proportion of correctly forwarded packets to correctly forwarded packets to the total number of packets the total number of packets

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Reputation Handling Reputation Handling ModuleModule Reputation information collectingReputation information collecting

– SensingSensing– RecommendationsRecommendations

Reputation information templateReputation information template Reputation information Reputation information

maintenancemaintenance Reputation ratingReputation rating

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Reputation Handling Reputation Handling ModuleModule Reputation information collectingReputation information collecting Reputation information templateReputation information template

Reputation information Reputation information maintenancemaintenance

Reputation ratingReputation rating

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Reputation Handling Reputation Handling ModuleModule Reputation information collectingReputation information collecting Reputation information templateReputation information template Reputation information Reputation information

maintenancemaintenance

Reputation ratingReputation rating

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Reputation Handling Reputation Handling ModuleModule Reputation information collectingReputation information collecting Reputation information templateReputation information template Reputation information maintenanceReputation information maintenance Reputation ratingReputation rating

– Proportion of correctly forwarded packets with respect to the total number of packets to be forwarded during a fixed time window

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Trust Model 3Trust Model 3 Trust is defined based on the Trust is defined based on the

following factors:following factors:– Experience statisticsExperience statistics– Data valueData value– Intrusion black list Intrusion black list – ReferenceReference– Personal preferencePersonal preference

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Secure Routing Based on Secure Routing Based on Model 3Model 3

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SummarySummary Trust in ad hoc networks can not be treated Trust in ad hoc networks can not be treated

as a property of trusted systems but rather as a property of trusted systems but rather it is an assessment based on experience it is an assessment based on experience that is shared through networks of peoplethat is shared through networks of people

Hard-security cryptographic or certification Hard-security cryptographic or certification mechanisms are not feasiblemechanisms are not feasible

Confidence measures should be built Confidence measures should be built dynamically based on effort/return dynamically based on effort/return mechanismmechanism

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ReferencesReferences1.1. Asad Amir Pirzada, Chris McDonald: Establishing Trust In Asad Amir Pirzada, Chris McDonald: Establishing Trust In

Pure Ad-hoc Networks. ACSC 2004, pp. 47-54, 2004. Pure Ad-hoc Networks. ACSC 2004, pp. 47-54, 2004. 2.2. Patrick Albers, Olivier Camp, Jean-Marc Percher, Bernard Patrick Albers, Olivier Camp, Jean-Marc Percher, Bernard

Jouga, Ludovic Mé, Ricardo Staciarini Puttini: Security in Jouga, Ludovic Mé, Ricardo Staciarini Puttini: Security in Ad Hoc Networks: a General Intrusion Detection Ad Hoc Networks: a General Intrusion Detection Architecture Enhancing Trust Based Approaches. Wireless Architecture Enhancing Trust Based Approaches. Wireless Information Systems , pp. 1-12, 2002. Information Systems , pp. 1-12, 2002.

3.3. Yacine Rebahi, Vicente E. Mujica V, Dorgham Sisalem: A Yacine Rebahi, Vicente E. Mujica V, Dorgham Sisalem: A Reputation-Based Trust Mechanism for Ad Hoc Reputation-Based Trust Mechanism for Ad Hoc Networks. ISCC 2005, pp. 37-42, 2005. Networks. ISCC 2005, pp. 37-42, 2005.

4.4. Yan Sun, Wei Yu, Zhu Han, K. J. Ray Liu: Trust Modeling Yan Sun, Wei Yu, Zhu Han, K. J. Ray Liu: Trust Modeling and Evaluation in Ad Hoc Networks. Global and Evaluation in Ad Hoc Networks. Global Telecommunication Conference 2005.Telecommunication Conference 2005.

5.5. Zheng Yan , Peng Zhang , Teemupekka Virtanen: Trust Zheng Yan , Peng Zhang , Teemupekka Virtanen: Trust Evaluation Based Security Solution in Ad Hoc Networks. Evaluation Based Security Solution in Ad Hoc Networks. Proceedings of the Seventh Nordic Workshop on Secure IT Proceedings of the Seventh Nordic Workshop on Secure IT Systems, 2003. Systems, 2003.

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Questions???Questions???