Transcript TAODV: A Trusted AODV Routing Protocol for MANET Li Xiaoqi, GiGi

TAODV: A Trusted
AODV Routing
Protocol for MANET
Li Xiaoqi, GiGi
Term Presentation
2004-4-27
Outline
Introduction
 Framework of TAODV
 Trust model for TAODV
 Routing operations in TAODV
 Analyses and simulations
 Conclusion

2
Now Comes to:
Introduction
 Framework of TAODV
 Trust model for TAODV
 Routing Operations in TAODV
 Analyses and Simulations
 Conclusion

3
Introduction

Mobile Ad Hoc Network (MANET)
 No
fixed infrastructure
 Multi-hop routing by cooperation of nodes in a
self-organized way
 Nodes has high mobility
 Underlying medium is wireless
 Frequent link layer errors
 Vulnerable to kinds of attacks
4
Routing Protocols for MANET

DSR:
 The

Dynamic Source Routing Protocol
DSDV:
 Destination-Sequenced

Distance Vector Protocol
AODV:
 Ad
Hoc On-Demand Distance Vector Protocol
 Two main routing messages:


RREQ: Routing REQuest
RREP: Routing REPly
5
Applications of MANET




Personal area networking
Meeting rooms
Disaster relief
Battlefield operations
 High Security Requirements
6
Previous Security Solutions for
MANET

Secure routing protocol
 may
perform digital signature authentication
at each routing message
 huge overhead

Key management mechanism
 usually
need a super-trusted third-party to
issue certificates
 destroy the self-organization nature of
MANET
7
Previous Security Solutions for
MANET (con’d)

Intrusion detection mechanism
 Listen,
collect and analyze all traffics on each
node
 Huge process overhead
Our aim is to design a secure routing protocol,
called TAODV (Trusted AODV Routing Protocol),
without introducing huge overhead or destroying
the self-organization nature of MANET
8
Now Comes to:
Introduction
 Framework of TAODV
 Trust model for TAODV
 Routing Operations in TAODV
 Analyses and Simulations
 Conclusion

9
Main Ideas of TAODV


A secure routing protocol for MANET
Use trust relationships among nodes for routing
 Employ
a trust model derived from subjective logic
 Trust calculation is not very time-consuming
 Need not sign and verify digital signature at each
routing message

Cooperate with a self-organized key
management mechanism
 such

as some threshold solutions
We take AODV for example to illustrate our idea
10
Four Modules of TAODV


Basic routing protocol (AODV in this work)
Trust model
 Define
the algorithms or rules to combine, judge, and
update trust information based on subjective logic


Trusted routing protocol
Self-organized key management mechanism
 generate
a {secret, public} key pair for each node and
distribute public keys in a secure self-organized way
 A pre-requisition, will not discuss it in this presentation
11
Module of Trusted Routing Protocol

Include operations of
 trust
recommendation
 trust combination
 trust judgement
 trust update
 signature authentication
 trust authentication
12
Framework of TAODV
Self-organized Key Management Mechanism
Signature
Authentication
Trust
Recommendation
Trust
Combination
Trust
Update
Trust
Judgement
Trust
Authentication
Basic Routing Protocol
Trust Model
13
Now Comes to:
Introduction
 Framework of TAODV
 Trust model for TAODV
 Routing Operations in TAODV
 Analyses and Simulations
 Conclusion

14
Representation of Trust

Use Opinion to represent trust:
 A two-dimensional,
but three-element metric
A
A
A
A


(
b
,
d
,
u
B
B
B)
 B



 We
bBA --
Probability of node A believing in node B
d BA -- Probability of node A disbelieving in node B
u BA-- Probability of node A’s uncertainty about B
define that
bBA  d BA  u BA  1
15
Combination of Trust

Discounting Combination: 
 Combine
trusts along one path
 Combine
 Equation:
B
A
C
 ( A  B) 
   ( A  C)
 ( B  C )
Let
 CAB  (bCAB , d CAB , uCAB )
 bCAB  bBAbCB
 AB
A B
d

b
 C
B dC
u AB  d A  u A  b Au B
B
B
B C
 C
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Combination of Trust (con’d)

A
Consensus Combination: 
 Combine
 Combine

C
trusts from several paths
B
 ( A  C)
   ( A, B  C )
 ( B  C )
A, B
A, B
A, B
A, B
Equation: Let  C  (bC , d C , uC )
 bCA, B  (bCAuCB  bCB uCA ) / k
 A, B
A B
B A
d

(
d
u

d
 C
C C
C uC ) / k , where k
u A, B  (u Au B ) / k
C C
 C
A
B
A
B
 u C  u C  2u C u C
17
Mapping Between Evidence and
Opinion space

Mapping from evidence space to opinion space:
 bBA  p  np
 A
A
n
d

,
where
u
 B p  n 
B  0,   0
u A  
 B p  n 

p : positive evidences
n : negative evidences
α is a parameter


imply the change rate of b, d, and u
we can adjust it to meet our application
18
Mapping Between Evidence and
Opinion space (con’d)

Mapping from opinion space to evidence space:
 p  b / u

n   d / u

, where u  0
We can update trust information from evidence
space mapping to opinion space, or vice versa
19
Now Comes to
Introduction
 Framework of TAODV
 Trust model for TAODV
 Routing Operations in TAODV
 Analyses and Simulations
 Conclusion

20
Trust Recommendation
Exchange trust information
 Three types of message:

 TREQ:
Trust REQuest
 TREP: Trust REPly
 TWARN: Trust WARNing

Broadcast TWARN when a node’s disbelief value
is zero
21
Trust Recommendation (con’d)

Message Structure
 TREQ

 TREP

22
Trust Judgement

Predefined trust judging rules
b
d
u
>h
>h
Request and verify digital signature
Distrust a node till next certificate renewal
>h
≤h
Actions
Trust a node and continue routing
≤h
≤h
Request and verify digital signature
b – belief
d – disbelief
u – uncertainty
h – threshold which can be adjusted to meet different security level
(default h=0.5)
23
Trust Update

Update of Evidences
Communication Positive events: p++
 Failed Communication Negative events: n++
 Successful
 Mapping

from opinion space
Update of opinion
 Combination
from different recommendations
 Mapping from evidence space
24
Routing Table Extension

Add three fields into original routing table
 Positive
events
 Negative events
 Opinion

New routing table format
DestIP DestSeq ... HopCount ... Lifetime
Positive
Events
Negative
Events
Opinion
25
Routing Message Extension

Add such fields into original routing messages
 Trust
information, or
 Digital signature information



RREQ  TRREQ
RREP  TRREP
Message structure:
original routing information
…
trust information or signature information
26
General Process of TAODV




On initialization, each node’s opinion towards others is
(0,0,1), which means total uncertainty of other nodes’
trustworthiness.
Nodes perform signature authentication during the
initialization period.
After some trust exchanges and data communications,
thus with the increase of either positive or negative
events, the uncertainty will be decreased and the trust
relationship among nodes are forming.
When the trust relationship in the network has been
established, the authentication of nodes will mainly use
trust authentication.
27
Trusted Routing Discovery
S
C
P
D
N




S originated a routing request to D
C is the current node
P is C’s precursor, N is the next hop
Suppose threshold=0.5
28
Routing Process at Current Node
step1:
Trust exchange
step2:
Authenticate P
step3:
Authenticate S
step4:
Authenticate D
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Routing Process at Current Node
Trust exchange for opinions to S, D, P
Combine  opinion(C,P)
d>0.5
Judge opinion(C,P)
U>0.5 or b,d,u<=0.5
b>0.5
Combine  opinion(C,S)
U>0.5 or b,d,u<=0.5
d>0.5
Judge opinion(C,S)
b>0.5
Combine  opinion(C, D)
d>0.5
Y
U>0.5 or b,d,u<=0.5
Judge opinion(C, D)
Have route?
b>0.5
Have route?
Signature authentication
N
enqueue
N
Y
Correct?
Y
Deny
TRREP
Re-TRREQ Wait for RREQ
TRREP
N
Deny
30
Now Comes to:
Introduction
 Framework of TAODV
 Trust model for TAODV
 Routing operations in TAODV
 Analyses and simulations
 Conclusion

31
Performance Analysis
Communication overheads can be sharply
reduced by avoiding signature generation
and verification at each routing message.
 Bandwidth overheads can be largely
reduced because of replacing 1024/2048
bit signatures to simple trust values.

32
Security Analysis




If no misbehavior, trust value will keep
increasing.
If an external malicious node, it will at once be
denied due to not providing valid signature.
We only consider to prevent external attacks.
Internal attacks can be eased through
certificates renewal.
33
Simulation Environment

Simulator: ns-2
Number of Nodes
30
Source-Destination Pairs
12
Simulation Fields
670*670m
Simulation Time
360s
Node Velocity Range
0-10m/s
Source Packet Rate
4pkts/s
Source Data Packet Size
512 bytes
Physical Link Bandwidth
2Mbps
Nominal Radio Range
250m
34
Selected Simulation Results
Throughput of receiving bits VS Average End2End delay (pause time: 10s)
35
Conclusion
TAODV is a trusted routing protocol which
cooperates with a self-organized key
management mechanism.
 It introduces less computation overheads
than previous secure routing protocol
solutions and also guarantee a certain
security level.
 It performs trusted routing in a selforganized way.

36
Q&A
Thank You!