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Trust Model Based Self-Organized Routing Protocol For Secure Ad Hoc Networks. Li Xiaoqi CSE Department, CUHK 29/04/2003. Outline. Introduction to Ad Hoc Networks Motivation and Design Goals Trust Model for Ad Hoc Networks Trusted Self-Organized Routing Protocol Conclusion

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trust model based self organized routing protocol for secure ad hoc networks

Trust Model Based Self-Organized Routing Protocol For Secure Ad Hoc Networks

Li Xiaoqi

CSE Department, CUHK

29/04/2003

outline
Outline
  • Introduction to Ad Hoc Networks
  • Motivation and Design Goals
  • Trust Model for Ad Hoc Networks
  • Trusted Self-Organized Routing Protocol
  • Conclusion
  • Research Plan and Future Work
now come to
Now Come to:
  • Introduction to Ad Hoc Networks
  • Motivation and Design Goals
  • Trust Model for Ad Hoc Networks
  • Trusted Self-Organized Routing Protocol
  • Research Plan and Future Work
  • Conclusion
what is ad hoc network
What is Ad Hoc Network
  • A kind of network without fixed infrastructure such as base stations or access points, which performs communications through wireless media
  • Wireless applications in:
    • Military Operations
    • Disaster Relief
    • Meeting Room Setup for Conference
    • Personal Area Networking
characteristics of ad hoc networks
Characteristics of Ad Hoc Networks
  • No fixed infrastructure
  • Each node is a router
  • Multi-hop routing by nodes cooperation
  • Self-organization nature
  • High mobility
  • Prone to be attacked
routing protocols for ad hoc networks
Routing Protocols for Ad Hoc Networks
  • AODV:

-Ad Hoc On-Demand Distance Vector Protocol

  • DSR:

-The Dynamic Source Routing Protocol

  • DSDV:

-Destination-Sequenced Distance Vector Protocol

overview of aodv
Overview of AODV
  • Discover routes when needed
  • Mainly two types of routing messages:
    • RREQ: Route Request
    • RREP: Route Reply
  • Fixed-length messages
  • Only one mutable field: Hop Count
route discovery in aodv
Route Discovery in AODV

RREQ

Broadcast

S

D

RREP

RREP

now come to9
Now Come To:
  • Introduction to Ad Hoc Networks
  • Motivation and Design Goals
  • Trust Model for Ad Hoc Networks
  • Trusted Self-Organized Routing Protocol
  • Conclusion
  • Research Plan and Future Work
security requirements in ad hoc networks
Security Requirements in Ad Hoc Networks
  • Confidentiality
  • Authenticity
  • Integrity
  • Availability
  • Non-repudiation
  • Access Control
common solutions for security
Common Solutions for Security
  • Often assume
    • A trusted authority to issue certificates.
    • A centralized server to monitor the networks.
    • A secret association between certain nodes.
  • Disadvantages
    • Destroy the self-organization nature of ad hoc networks.
    • Limit the mobility of nodes.
    • Single point of failure
    • Less of efficiency and availability
self organized solutions for security
Self-Organized Solutions for Security
  • Properties
    • Authenticate each other in a self-organized way
    • Often issue certificate of a public key by nodes cooperation
    • Often need node monitoring mechanism
  • Disadvantages
    • Need at least k neighbors to cooperate
    • Monitoring mechanism is difficult to implement and is performance-consuming
current issues in ad hoc networks
Current Issues in Ad Hoc Networks
  • Lack of security consideration
  • Centralized server or trusted third parties destroy the self-organization nature
  • Pure cryptographic solutions bring high overhead
  • Current self-organized solutions lose flexibility
our solutions and design goals
Our Solutions and Design Goals
  • Design a suitable decentralized trust model that can be used for the security solutions of ad hoc networks.
  • Apply this trust model to design a flexible self-organized key management scheme.
  • Apply this trust model to design a secure and flexible self-organized routing protocol with lower overhead.
  • Demonstrate the principle of the trust model and the security advantages of the resulting ad hoc networks.
now come to16
Now Come To:
  • Introduction to Ad Hoc Networks
  • Motivation and Design Goals
  • Trust Model for Ad Hoc Networks
  • Trusted Self-Organized Routing Protocol
  • Research Plan and Future Work
  • Conclusion
trust model for ad hoc networks
Trust Model for Ad Hoc Networks
  • Overview of trust theory
    • Trust is a basic aspect of human life.
    • Trust is regarded as a measurable variable.
    • Trust theory has been applied into the fields of E-Commerce
  • Organization of nodes in ad hoc networks is similar as human society
    • Apply trust theory to secure ad hoc networks
previous trust models
Previous Trust Models
  • Direct and recommendation trust model
    • Continuous value to represent trust
    • Basis of many other trust models
  • Recommendation protocol model
    • Focus on the exchange of trust information
  • Dempster-Shafer Theory based model
    • Upper and lower bound pair to represent trust
    • Trust matrix to represent trust relationship
    • Combine two matrices using Dempster-Shafer theory
previous trust models con d
Previous Trust Models (Con’d)
  • Model using Fuzzy Logic
    • Trust matrix to represent trust relationship
    • Fuzzy logic to verify transactions
    • Fuzzy logic to combine trust matrices
  • Model using Subjective Logic
    • Use Opinion to represent trust
    • Opinion includes belief, disbelief, uncertainty
    • Combine trust using subjective logic
comparison of trust models
Comparison of Trust Models
  • Single trust value vs. Opinion
    • Opinion with belief, disbelief and uncertainty can express more information
  • Fuzzy logic vs. Subjective logic
    • Fuzzy logic operates on certain measures about fuzzy propositions
    • Subjective logic operates on uncertain measures about crisp propositions
comparison of trust models con d
Comparison of Trust Models (Con’d)
  • Shafer theory vs. Subjective logic
    • Both introduce uncertainty
    • No need to set upper or lower bounds of trust described in Shafer theory
design issues of trust model
Design Issues of Trust Model
  • Definition of Trust
  • Representation of Trust
  • Combination of Trust
  • Exchange of Trust Information
our trust model
Our Trust Model
  • Use ‘Opinion’ to define and represent trust
  • Combine trust opinions using subjective logic
  • Define a trust recommendation protocol to exchange trust information
definition and representation of trust
Definition and Representation of Trust
  • Opinion: a three-dimensional metric
  • The opinion about the trustworthiness of x, denoted by ωx , is the triple defined by:
    • b(x) represent belief: probability of believing x.
    • d(x) represent disbelief: probability of disbelieving x
    • u(x) represent uncertainty: probability of uncertainty about x’s trustworthiness
definition and representation of trust con d
Definition and Representation of Trust (Con’d)
  • Property of Opinion:
    • b, d, u is in [0,1]
    • b+d+u = 1
  • Opinion ωx (0.4,0.1,0.5) can be represented in the right figure.
combination of trust
Combination of Trust
  • Discounting Combination
    • Combine trusts along one path
    • Combine
  • Consensus Combination
    • Combine trusts from several paths
    • Combine
trust recommendation protocol
Trust Recommendation Protocol
  • Exchange trust information
  • Three types of message:
    • TREQ: Trust Request
    • TREP: Trust Reply
    • TWARN: Trust Warning
  • Message structure
our trust model vs subjective logic trust model
Our Trust Model vs. Subjective Logic Trust Model
  • Simplify the representation of trust, which is more suitable for ad hoc networks
  • Propose a trust recommendation protocol to exchange trust information
  • Handle the dynamic of trust which is not mentioned in subjective logic
now come to30
Now Come To:
  • Introduction to Ad Hoc Networks
  • Motivation and Design Goals
  • Trust Model for Ad Hoc Networks
  • Trusted Self-Organized Routing Protocol
  • Research Plan and Future Work
  • Conclusion
assumption of our trusted routing protocol
Assumption of Our Trusted Routing Protocol
  • Ability to recover node’s neighbors.
  • Reliability of broadcasting one-hop messages
  • Uniqueness of node’s ID
  • Capability of monitoring behaviors of one-hop neighbors
  • Key management has been done before
node model
Node Model
  • One node has an opinion about others
  • Each node maintains a trust table. For Example, A’s trust table is:
  • Initial opinion of a node in others’ eyes is (0,0,1)
general framework

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General Framework
cryptographic technologies
Cryptographic Technologies
  • Use cryptographic schemes to do routing in the beginning of this network
  • Adopt ideas in SAODV [42]
    • Digital signature: authenticate the non-mutable fields of the messages
    • Hash chains: secure the only mutable field ‘hop count’
overview of trusted self organized routing protocol
Overview of Trusted Self-Organized Routing Protocol
  • Effective when trust relationships have been established among most nodes
  • Based on AODV routing protocol
  • Criteria to determine whether a node can be trusted or not is:
    • belief≥0.5, disbelief<0.5, uncertainty<0.5
  • Nodes cooperate to decide a opinion
trust update algorithm
Trust Update Algorithm
  • Each value in a opinion is logically divided into 5 levels. Every 0.25 is one level.
  • Successful verification for ten times:
    • belief+=0.25, disbelief-=0.125, uncertainty-=0.125
  • Failed verification for each time:
    • belief-=0.125, disbelief+=0.25, uncertainty-=0.125
  • No verification during expiry time
    • belief-=0.375, disbelief+=0.125, uncertainty+=0.25
trust update algorithm con d
Trust Update Algorithm (Con’d)
  • If in opinion A to B,

belief<0 or disbelief>1

    • Opinion(AB) will be changed to (0,1,0)
    • Node A broadcast this opinion using TWARN message
    • Neighbors will re-calculate the opinion using trust combination algorithm
    • B will be denied from A’s communication
trusted key management
Trusted Key Management
  • Use trust model into key management
  • Advantages:
    • Self-organization
    • Flexible: no limitation of at least k neighbors
    • Lower overhead
analysis
Analysis
  • Performance is increased
    • No need to perform cryptographic calculations for every packet  lower overhead
  • Security is enhanced
    • Combination of trust model, cryptographic schemes and monitor mechanism
  • More reasonable and flexible
    • Good nodes who become bad will be denied from network eventually
    • Bad nodes who turn to good will be allowed accessing network again soon
now come to41
Now Come To:
  • Introduction to Ad Hoc Networks
  • Motivation and Design Goals
  • Trust Model for Ad Hoc Networks
  • Trusted Self-Organized Routing Protocol
  • Conclusion
  • Research Plan and Future Work
conclusion
A promising idea to apply trust model to secure ad hoc networks

Node uses ‘opinion’ to judge if another node is trustable

Nodes cooperate to obtain a more accurate opinion

Trusted routing protocol is

Self-organized

Lower-overhead

More reasonable

More secure

More flexible

Conclusion
research plan and future work
Research Plan and Future Work
  • A better trust combination algorithm
  • A better way to apply trust model into key management
  • Study monitor or intrusion detection issues
  • Improve trusted routing protocol to make it prevent or stand more attacks
  • A detailed simulation evaluation using NS-2 or Glomosim simulators
slide44
Q&A

Thank you !

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