Automatic Trust Negotiation
Presented by: Scott Hackman
Scott Hackman – CS5204 – Operating Systems
1
Automatic Trust Negotiation
Reference

Trust-X: A Peer-to-Peer Framework for Trust
Establishment
Elisa Bertino, Elena Ferrari, Anna Cinzia Squicciarini
Scott Hackman – CS5204 – Operating Systems
2
Automatic Trust Negotiation
What Is Trust Negotiation?




Would you give your credit card number to a website if you
didn’t know who was running it?
No! The Internet is a hostile environment where identities
aren’t always known. Sensitive information transfer can be
dangerous under these conditions.
This paper establishes a framework to allow two parties,
who may have never interacted before, to exchange
information in a bilateral and incremental way to gain each
other’s trust prior to divulging sensitive information.
We perform the same fundamental algorithm every day
when we interact with people.
Scott Hackman – CS5204 – Operating Systems
3
Automatic Trust Negotiation
About The Paper

Trust-X: A Peer-to-Peer Framework for Trust
Establishment is designed to compile work
already done in this field, along with some added
novel concepts by the authors, to create an
implementable architecture for Trust
Establishment.
Scott Hackman – CS5204 – Operating Systems
4
Automatic Trust Negotiation
ATN is NOT Encryption


Trust Negotiation is designed to work with public
key encryption: Even though you may possess an
x-bit key that can’t be cracked, there is no
guarantee that the person, or computer, that you
are interacting with is who they say they are.
Public key encryption should be used to pass data
between two entities to ensure confidential data
transfer; ATN verifies identity and qualification,
not data security.
Scott Hackman – CS5204 – Operating Systems
5
Automatic Trust Negotiation
XML Syntax Example
Scott Hackman – CS5204 – Operating Systems
6
Automatic Trust Negotiation
Trust-X Basics

Generally, interactions between two entities:
Controllers (CN)
Requesters (RQ)

Information that is passed:
Credentials – More sensitive information
Declarations – Less sensitive – Ex: user preferences.

Negotiation Phase:
Two parties perform a back-and-forth negotiation until both
parties agree on a chain of events that will get them to their
goal state (DELIV). It is important to remember, that no actual
data is passed during this phase (they agree when to pass credit
card data in their chain, but that actual data isn’t passed yet)
Scott Hackman – CS5204 – Operating Systems
7
Automatic Trust Negotiation
Trust-X Basics

Policies:
The “rules” that each entity establishes for its own
protection. For example, “I won’t give an employee a
rental car until I know they have a valid ID and
company badge.”
Scott Hackman – CS5204 – Operating Systems
8
Automatic Trust Negotiation
Architecture for Trust-X Negotiation
Scott Hackman – CS5204 – Operating Systems
9
Automatic Trust Negotiation
Policy Example
- Employees can rent with a company badge and ID card.
- Non-employees can rent with drivers license and credit card.
Scott Hackman – CS5204 – Operating Systems
10
Automatic Trust Negotiation
Policies – Big Picture
How to build
Trust.
Scott Hackman – CS5204 – Operating Systems
11
Automatic Trust Negotiation
Negotiation Process
Taken from Prof. Kafura’s PowerPoint which was modified from
http://www.ccs.neu.edu/home/ahchan/wsl/symposium/bertino.ppt
Scott Hackman – CS5204 – Operating Systems
12
Automatic Trust Negotiation
Well-formed chain

How do we know a set of policies will let us achieve our goal?
(Decided during negotiation)
Scott Hackman – CS5204 – Operating Systems
13
Automatic Trust Negotiation
Negotiation Tree

A tree that traverses valid policies between the
Controller and Requester until an agreement is
met that goes from initial communication to
DELIV state (or Fail state if none exist).
Scott Hackman – CS5204 – Operating Systems
14
Automatic Trust Negotiation
Negotiation Tree Basics
Scott Hackman – CS5204 – Operating Systems
15
Automatic Trust Negotiation
Negotiation Tree Example
Scott Hackman – CS5204 – Operating Systems
16
Automatic Trust Negotiation
Questions?
Scott Hackman – CS5204 – Operating Systems
17