Trust-Based Security Protocols
Henry Hexmoor, Sandeep
Bhattaram, and Seth L. Wilson
University of Arkansas
Fayetteville, Arkansas 72701
1
Orientation
• AI/agents group working on knowledge
representation and management…
• Our Primary focus is on design and implementation
of socially adept agents…
• “Soft security” as our newest KR&M research area
with modest AFOSR funding…
2
Orientation and Premise
• Information sharing among disparately-located
individuals with security concerns for confidentiality
and integrity… sensor networks…
• Existing organizational policies lack in impersonal
nature of the work environments and mutuality of
trust and respect.
• We are developing trust-based security policies in
information sharing that consider “trust” as the key
parameter…
3
Preliminaries
• Interpersonal Trust: Agent x’s trust in agent y is agent x’s estimation
•
•
•
•
of the probability that agent y will preserve agent x’s welfare with
regard to actions to be performed
If a fact initiator agent determines that their trust in a recipient agent
does not warrant them to receive the fact, then the recipient agent is
considered to be an unintended receiver.
Imagine a DAG of trust, i.e., a trust network…
A trust policy prescribes a trust update policy that regulates changes in
interpersonal trust relations in the first order to reduce unintended
receivers while increasing the rate of information sharing.
The larger goal is to establish and maintain enterprise KM regimes
and to regulate information sharing topologies…
4
Towards System-wide Metrics…
Information availability, IA, is the degree to
which information is freely available when
shared among a group of agents. IA, a system
level metric, is the sum of number of satisfied
agents and the number of intended receivers
expressed as a percentage of the total facts
shared.
Security Measure, SM, is a system level metric,
that measures the number of unintended
receivers expressed as a percentage of the total
facts shared.
5
A simulation with randomized facts and
agents…
120
IA and SM over Cycles w ithout trust update
policies
IA
IA and SM
100
SM
80
60
40
20
0
0
5
10
15
20
Cycles
25
30
35
6
A intuitive observation…
IA Saturation Cycle
14
12
10
8
6
4
2
0
0
1
2
3
4
Degrees of policy restriction
5
6
7
Another observation…
1400
Total Facts Shared over Trust Threshold
1200
1000
800
600
400
200
0
0.1
0.25
Trust Threshold
0.5
0.7
8
Conclusion
•The trust-based information sharing model sufficiently and
effectively guarantees the high availability of information while
limiting security breaches.
•Our simulations have demonstrated that the use of a “soft security”
mechanism such as trust is as effective as hard security mechanisms.
•The inherent advantage of our model is in its simplicity,
malleability, and scalability.
9