1 Token–based Dynamic Trust Establishment for Web Services Zhengping Wu and Alfred C. Weaver Department of Computer Science University of Virginia March 2005

2 Outline Motivation and Contributions State of the Art Trust Primitive and Selective Disclosure Trust Group and Dynamic Validation Token-based Solution for Web Service Trust Establishment Conclusion and Future Work

3 Motivation - 1 Step 1: A consumer requests enrollment service from a bank Step 2: The bank discloses its policy P to the consumer Step 4: The bank grants access to the enrollment service Step 3: The consumer discloses her driver’s license to the bank Bank Enrollment Service Consumer

4 Motivation - 2 Need for trust relationships in web services environment Need for security and privacy protection for sensitive information Need for better mechanisms to address information leakage in trust establishment processes Need for dynamic capability to keep track of changes in trust relationships

5 Contributions The proposed trust establishment mechanism fully protects the requester’s privacy. The proposed trust establishment mechanism is capable of disclosing private attributes selectively. The proposed trust establishment mechanism allows the established trust relationship to be updated by following the changes of the service provider’s policy.

6 Motivation and Contributions State of the Art Trust Primitive and Selective Disclosure Trust Group and Dynamic Validation Token-based Solution for Web Service Trust Establishment Conclusion and Future Work

7 State of the Art Identity-based trust establishment mechanisms (common in e-commerce) Role-based trust establishment mechanisms Group-based trust establishment mechanisms

8 Motivation and Contributions State of the Art Trust Primitive and Selective Disclosure Trust Group and Dynamic Validation Token-based Solution for Web Service Trust Establishment Conclusion and Future Work

9 Selective Disclosure Causes of information leakage in real life trust establishment A credential may not be used for its intended purpose A pre-packaged credential may reveal more information than is necessary Selective Disclosure Use of available pre-packaged credentials Control of information disclosure with credential holder’s will Trust primitive

10 Trust Primitive Attributes: Attribute 1 (name) Attribute 2 (ID number) Attribute 3 (gender) Attribute 4 (student/faculty/ staff status) Attribute 5 (address) Attribute 6 (token expiration) Attribute 7 (token issuer) Trust primitive 1 (electronic library access) Trust primitive 2 (library checkout) Trust primitive 3 (dorm floor entrance)

11 Trust Primitive Service provider’s security domain Requester’s security domain Requester Service Provider Security Token Service Attribute Service Security Token Service 4 Workflow of Negotiation Using Trust Primitives

12 Motivation and Contributions State of the Art Trust Primitive and Selective Disclosure Trust Group and Dynamic Validation Token-based Solution for Web Service Trust Establishment Conclusion and Future Work

13 Dynamic Validation Representation of the established trust relationship Trust group element in security token Requirement of trust group element in policy Same policy with same trust group name Dynamic validation Change of policy indicates new trust relationship Change of policy requires revalidation of trust group element

14 Trust Group Banking Customers share the same set of requirements in policy 1. Mortgage Customers share the same set of requirements in policy 2.

15 Motivation and Contributions State of the Art Trust Primitive and Selective Disclosure Trust Group and Dynamic Validation Token-based Solution for Web Service Trust Establishment Conclusion and Future Work

16 dynamic trust (trust group) request Security Token Service Negotiation Engine Web Service Provider Web Service Requester Security Token Service Negotiation Engine Attribute Service Architecture of the Solution

17 Motivation and Contributions State of the Art Trust Primitive and Selective Disclosure Trust Group and Dynamic Validation Token-based Solution for Web Service Trust Establishment Conclusion and Future Work

18 Conclusion The proposed trust establishment mechanism allows the requestor to control what attributes are disclosed to the service provider avoids disclosing more than is necessary which may happen with pre-packaged credentials dynamically negotiates new credentials as necessary to follow changes in policy

19 Future work Extension of trust primitive and trust group mechanisms to allow privacy control during delegation to allow privacy protection during delegation

20 The End Questions?