A Survey of Trust Management Systems Speaker: Dalal Al-Arayed PhD-IT Student Supervised by: João Pedro Sousa, PhD Assistant Professor, CS, GMU

Outline What is Trust? What is Trust Management? Types of Models Main Problem Domains Trust Management Approaches Genealogy of Models Covered Description of Models Conclusion ◦ Evolution of Trust Management Models

What is Trust? Sociologist Diego Gambetta: ◦ Trust is a particular level of the subjective prob. with which an agent will perform a particular action, before [we] can monitor such action and in a context in which it affects [our] own action.

What is Trust? Cont. Trust is context-dependent, dynamic & non- monotonic. Types of Trust ◦ Interpersonal (agent & context specific) ◦ Structural (system within which trust exists) ◦ Dispositional (independent of agent & context)

What is Trust Management ? “Trust Management” was first coined by Blaze et. al 1996 ◦ a coherent framework for the study of security policies, security credentials and trust relationships. ◦ Two of the first TM systems PolicyMaker and KeyNote.

Two Types of Models Trust Management models ◦ Certificate-based ◦ Reputation-based (behavior observed directly or indirectly)  Recommendations: trust information shared among peers

Main Problem Domains Service Provision ◦ Blaze et.al (1996, 1998)- PolicyMaker & Keynote ◦ Abdul-Rahman & Hailes (2000) ◦ Aberer & Despotovic (2001) ◦ Capra (2004)- hTRUST ◦ McNamara et al.(2006) ◦ Quercia & Hailes (2006)-MATE Routing ◦ Buchegger et al. (2002)-CONFIDANT ◦ Cahill et al. (2003)-SECURE ◦ Quercia et al. (2006)-STRUDEL

Trust Management Approaches Individual Initiative (Anarchist) ◦ each agent is responsible for his own fate. Global Trust ◦ each peer in the system has a unique global trust value that other peers can access. Federated Trust ◦ management of trust-related activities across multiple and heterogeneous security domains and autonomous systems. ◦ deals with strategies for managing inter-domain behaviors

Genealogy of Models Anarchist Trust Global TrustFederated Trust AT&T Labs- Policy Maker (1996) KeyNote(1998) Abdul-Rahman & Hailes (2000) Aberer & Despotovic (2001) EigenTrust (2003) CONFIDANT (2002) SECURE (2003) UCL- hTRUST (2004) McNamara et al. (2006) STRUDEL (2006) MATE (2006) Donato et al. (2007) Chun & Bavier(2004) Bhargav et al.(2007)

Genealogy of Models Term: “Trust Management” PKI environments Certificate-based Trust Model Binds keys to actions AT&T Labs- Policy Maker (1996) KeyNote(1998) Abdul-Rahman & Hailes (2000) Aberer & Despotovic (2001) EigenTrust (2003) CONFIDANT (2002) SECURE (2003) UCL- hTRUST (2004) McNamara et al. (2006) STRUDEL (2006) MATE (2006) Donato et al. (2007) Chun & Bavier(2004) Bhargav et al.(2007)

PolicyMaker & Keynote (1996, 1998) Appears like a db query engine to the application. do not directly enforce policy; they only provide advice to the applications that call it. yes/no or additional requirements for request to be acceptable PolicyMakerApplication INPUT Local policies, authenticated credentials, action string OUTPUT

Genealogy of Models Reputation-based Trust Model Agents Autonomously reason about Trust Each Agent- Db of recorded experience. Recommendations exchanged AT&T Labs- Policy Maker (1996) KeyNote(1998) Abdul-Rahman & Hailes (2000) Aberer & Despotovic (2001) EigenTrust (2003) CONFIDANT (2002) SECURE (2003) UCL- hTRUST (2004) McNamara et al. (2006) STRUDEL (2006) MATE (2006) Donato et al. (2007) Chun & Bavier(2004) Bhargav et al.(2007)

Genealogy of Models Reputation-based Trust Model Stored & shared data is exclusively negative(complaints) Distributed Storage AT&T Labs- Policy Maker (1996) KeyNote(1998) Abdul-Rahman & Hailes (2000) Aberer & Despotovic (2001) EigenTrust (2003) CONFIDANT (2002) SECURE (2003) UCL- hTRUST ( 2004 ) McNamara et al. (2006) STRUDEL (2006) MATE (2006) Donato et al. (2007) Chun & Bavier(2004) Bhargav et al.(2007)

Genealogy of Models AT&T Labs- Policy Maker (1996) KeyNote(1998) Abdul-Rahman & Hailes (2000) Aberer & Despotovic (2001) EigenTrust (2003) CONFIDANT (2002) SECURE (2003) UCL- hTRUST (2004) McNamara et al. (2006) STRUDEL (2006) MATE (2006) Donato et al. (2007) Chun & Bavier(2004) Bhargav et al.(2007) Detection & isolation of misbehaved nodes Neighborhood watch shared data is exclusively negative (warnings) Local storage of trust values

CONFIDANT (2002) -EPFL

Genealogy of Models AT&T Labs- Policy Maker (1996) KeyNote(1998) Abdul-Rahman & Hailes (2000) Aberer & Despotovic (2001) EigenTrust (2003) CONFIDANT (2002) SECURE (2003) UCL- hTRUST (2004) McNamara et al. (2006) STRUDEL (2006) MATE (2006) Donato et al. (2007) Chun & Bavier(2004) Bhargav et al.(2007) Incorporates trust model & risk model Distinguishes between unknown and distrusted entities Enables delegation of trust evaluation Local storage of trust values

SECURE Project(2003)-EU

Genealogy of Models AT&T Labs- Policy Maker (1996) KeyNote(1998) Abdul-Rahman & Hailes (2000) Aberer & Despotovic (2001) EigenTrust (2003) CONFIDANT (2002) SECURE (2003) UCL- hTRUST (2004) McNamara et al. (2006) STRUDEL (2006) MATE (2006) Donato et al. (2007) Chun & Bavier(2004) Bhargav et al.(2007) Distributed trust models (Anarchist) Local storage of trust values

hTRUST (2004)-UCL Trust Model that facilitates trust formation, dissemination and evolution. Human Trust- customizing functions capture user’s trust disposition. Detect & isolate malicious recommenders

hTrust(2004)-Locally Stored Data AgentTrustKnowledgetimeStamp RecommenderTrustKnowledgetimeStamp RecommendedRecommenderTrustt ( ) SK recommender Portfolio of Credentials Tacit Tuples Aggregate Trust Tuple

hTRUST (2004)

McNamara et al. (2006)- UCL Trustworthiness – enables predictions about actual QoS given promised QoS Mobility introduced as parameter for decision making ◦ service requester and provider co-located for sufficient time to complete service delivery ◦ Mobility pattern: based on past journeys.

McNamara et al. (2006)- UCL Agent makes request for service Co-located agents respond ◦ Promised QoS ◦ Mobility Pattern Selection to maximize Requestor’s Utility

STRUDEL (2006)- UCL Coalition Peering Domain Tragedy of the commons STRUDEL: distributed framework ◦ Approach for detecting malicious nodes based on the 2-ACK scheme ◦ Trust Model ◦ Forwarding mechanism (decision model).

STRUDEL(2006)- 2 ACK Scheme If X does not receive ack from Y, Y is marked as unresponsive. If X does not receive ack from Z, Y is marked as suspicious ◦ Y did not send the packet to Z ◦ or Y relied on an untrustworthy peer Z. XYZ

MATE (2006)- UCL Attempts integrated mgt of trust & risk for decision making Expected utility theory incorporates trust info of sources, risk attitude of user, & context (location type) Risk restricted to timeliness of delivery.

MATE (2006)- Limitations risks scenario if component suppliers do not provide software within the agreed time ranges. Do not examine the potential risks from the way a software component actually operates. This situation might arise if the software component is signed with the author's key, thus guaranteeing the software integrity, and author is highly trusts.

Evolution of Trust Models Target Environ. Idea AT&T labs(1996, 1998) PKIA lot like Access Control Abdul- Rahman & Hailes (2000) Virtual comm. Intro to Reputation-based Trust Models & agents autonomy Aberer & Despotovic (2001) P2PAttempts distributed Storage of Trust info. CONFIDANT (2002) Mobile Ad- hoc Attempts incorporation of Detection & isolation of misbehavior SECURE (2003) Ubiquitous roaming entities Attempts Incorporation of risk model with Trust

Evolution of Trust Models- Cont. Target Environ. Idea hTrust(2004)Mobile ad- hoc Trust Management & dispositional trust. Detection & isolation of malicious recommenders. The HOW question is answered. McNamara et al. (2006) Mobile ad- hoc Mobility introduced as a factor STRUDEL (2006) CPD Combat Tragedy of the commons (Selfishness of Nodes) MATE (2006)Mobile ad- hoc Attempts integrated management of trust and risk (an element of dispositional trust).

Questions?

References Abdul-Rahman, A. and Hailes, S. “Supporting Trust in Virtual Communities”. In Proceedings of the 33rd Hawaii International Conference on System Sciences, Aberer, K. and Despotovic, Z. “Managing Trust in a Peer-2-Peer Information System”. In Proceedings of the 10th ACM International Conference on Information and Knowledge Management, Atlanta, USA, November Bhargav-Spantzel, A., Squicciarini, A. and Bertino, E. “Trust Negotiation in Identity Management”. In IEEE Security and Privacy, volume 5, issue 2, pages 55—63, March Blaze, M., Feigenbaum, J. and Lacy, J. “Decentralized Trust Management”. In Proceedings of IEEE Symposium on Security and Privacy, pages , Oakland, CA, May Blaze, M., Feigenbaum, J. and Keromytis, A. “KeyNote: Trust Management for Public-Key Infrastructures”. In Proceedings of the 6th International Workshop on Security Protocols, volume 1550 of Lecture Notes in Computer Science, pages , Cambridge, UK, April Springer-Verlag. Blaze, M., Feigenbaum, J., Ioannidis, J. and Keromytis, A. “The KeyNote Trust Management System, Version 2. RFC-2704”. IETF, September Blaze, M., Feigenbaum, J., Ioannidis, J. and Keromytis, A. “The Role of Trust Management in Distributed Systems Security”. In Secure Internet Programming: Security Issues for Mobile and Distributed Objects, pages , Buchegger, S. and Le Boudec, J. “Performance Analysis of the CONFIDANT Protocol: Cooperation of Nodes — Fairness in Dynamic Ad-hoc Networks”. In Proceedings of IEEE/ACM Symposium on Mobile Ad Hoc Networking and Computing (MobiHOC), Lausanne, CH, June 2002.

References- Cont. Cahill, V., Gray, E., Seigneur, J., Jensen, C., Chen, Y., Shand, B., Dimmock, N., Twigg, A., Bacon, J., English, C., Wagealla, W., Terzis, S., Nixon,P., Serugendo, G., Bryce,C., Carbone, M., Krukow, K.and Nielsen, M. “Using Trust for Secure Collaboration in Uncertain Environments”. In IEEE Pervasive Computing Mobile and Ubiquitous Computing, volume 2, issue 3, pages 52-61, July-Sept Capra, L. “Engineering human trust in mobile system collaborations”. In Proceedings of the 12th International Symposium on Foundations of Software Engineering, pages , Newport Beach, CA, USA, November ACM Press. Chun, B. and Bavier, A. “Decentralized Trust Management and Accountability in Federated Systems”. In Proceedings of the 37 th Hawaii International Conference of System Sciences, Jan Donato,D., Paniccia, M., Selis, M., Castillo, C., Cortese, G. and Leonardi, S. “New metrics for reputation Management in P2P networks”. In Proceedings of the 3 rd International Workshop on Adversarial Information retrieval on the web, May ACM. Kamvar, S., Schlosser, M., Garcia-Molina, H. “The Eigentrust Algorithm for Reputation Management in P2P Networks.” In Proceedings of the 12th International Conference on WWW, New York, USA, ACM Press, pages , Mcnamara, L., Mascolo, C. and Capra, L. "Trust and Mobility aware Service Provision for Pervasive Computing". In Int. Workshop on Requirements and Solutions for Pervasive Software Infrastructures (co-located with Pervasive 2006), Dublin, Ireland, May Quercia, D., Lad, M., Hailes, S., Capra, L. and Bhatti, S. “STRUDEL: Supporting Trust in the Dynamic Establishment of peering coaLitions”. In Proceedings of the 21st ACM Symposium on Applied Computing, Dijon, France, April Quercia, D. and Hailes, S. “MATE: Mobility and Adaptation with Trust and Expected-utility”. International Journal Internet Technology and Secured Transactions (IJITST), volume 1, 2007.