Introduction Out Outline e Imagine an Ad-hoc network - PowerPoint PPT Presentation

Wireless Ad Hoc and Sensor Networks Outline Out e - Trust and Soft Security • Introduction • Security techniques • Trust and reputation systems • Generic Trust and Reputation Model Scheme • Proposed models for ad hoc and sensor networks – CONFIDANT – CORE – RFSN RFSN WS 2010/2011 WS 2010/2011 • Problems exist in reputation systems Prof. Dr. Dieter Hogrefe • Summary • Summary Dr. Omar Alfandi 2 Introduction Out Outline e Imagine an Ad-hoc network • Introduction • Security techniques How can nodes in a cooperative communications • Trust and reputation systems • Rely on each other? R l h h ? • Generic Trust and Reputation Model Scheme • Decide whether and with • Proposed models for ad hoc and sensor networks whom to interact in this whom to interact in this – CONFIDANT uncertain conditions? – CORE – RFSN RFSN These risks can be mitigated through • Problems exist in reputation systems soft security mechanisms soft security mechanisms • Summary • Summary 3 4

Security Techniques Security Techniques B: Soft security: A: Hard security: • protect something from harm in quite and unremarkable ways. • traditional way of protecting data by putting hard fences traditional way of protecting data by putting hard fences • It is invisibly and after the fact to maintain the CIA (Confidentiality, Integrity an • used for social control mechanism availability) properties with: y) p p – It is the participants themselves – Authentication who are responsible for the security – Access Control – is collaborative and based on – etc. whole community • Leaves the security to some – doesn’t deny the existence of the malicious participants of the malicious participants external or global authority t l l b l th it – but avoid to interact with the • Reveals everything if they are bypassed malicious one • Example: Password • Example: Trust and Reputation Systems 5 6 Notion of Trust Outline Out e Trust is a directional relationship consists of: • Introduction • Trustor • Security techniques • Trustee • Trust and reputation systems • Scope A B • Generic Trust and Reputation Model Scheme Trustor Trustee • Proposed models for ad hoc and sensor networks – CONFIDANT – CORE • A can trust on B if B acts as the same way that A y – RFSN RFSN expects! And It shows to what extend does A have the • Problems exist in reputation systems feeling of security on B • Summary • Summary 7 8

Trust Network: Web of Trust Transitivity of Trust • Trust Network (Web of Trust) : The network of relationship between - vertex ~ mobile node 1 nodes that shows the level of trust nodes that shows the level of trust Alice Bob - direct edge ~ level of trust between them. 0 0.9 0.3 0 2 0.2 1 • Properties of Trust: Alice Bob Dave Carol – weighted, [0 = distrust, 1= trust] 0 0.6 0.9 0 9 – subjective/personal bj ti / l 0.2 – asymmetric Dave – dynamic ? Caro l 0.6 0 6 – non-monotonic t i – transitive 9 10 Trust Metrics Trust Management • Is a measure of how a member of a Trust management is the activity of gathering , group is trusted by the other member. 1 encoding analyzing and presenting evidence encoding , analyzing and presenting evidence Alice Bob • Using existing edges for predicting 0 relating to honesty and security with the purpose 0.9 0.3 values of trust for non existing edges 0.2 of making decisions regarding trust relationships. of making decisions regarding trust relationships using trust transition. i t t t iti Dave Carol (if you trust someone then, you have 0.6 some degree of trust in any one that g y • Policy-base trust management • Policy base trust management person trusts) ? • Reputation-based trust management • Goal: reduce uncertainty, by G l d t i t b Trust (Alice, Dave) = ? predicting how much each unknown people could be trusted. 11 12

Policy-Based Trust Reputation-Based Trust • Using policies to establish trust • Reputation: – The overall quality or character as seen or • Managing and exchanging credentials judged by people in general j d d b l i l • Enforcing access policies • I trust you because of your good reputation • Using trusted third party for issuing and verifying • I trust you despite your bad reputation y p y p credentials • Example: • Reputation-based trust p – PGP (Pretty Good Privacy) – Using reputation to establish trust – Using the history of an entity’s behaviors/actions b h i / ti – Combining first-hand knowledge and recommendation made by others and recommendation made by others 13 14 Reputation Network Architecture: Centralized Reputation Network Architecture: Distributed • No reputation center • Central authority – Distributed stores Di t ib t d t (reputation center) • Where rating can be – Collects all rating about submitted each participants who is each participants who is rated by other members – Each participants after a direct experience. • Records the opinion about others b t th – Derives a reputation score D i t ti for each participants. • Provide this information – Makes all scores publicly p y on request from relying q y g party. available. e.g. Peer-to-Peer, Ad-hoc Networks e.g. eBay 15 16

Generic Trust and Reputation Model Scheme Outline Out e Gathering 1 • Introduction information • Security techniques • Trust and reputation systems • Generic Trust and Reputation Model Scheme • Proposed models for ad hoc and sensor networks – CONFIDANT – CORE – RFSN RFSN • Problems exist in reputation systems • Summary • Summary 17 18 Gathering Information Generic Trust and Reputation Model Scheme • Gather its own opinion if Gathering information 1 there exist any direct 1 A B interactions: i t ti 0 0.9 – First-hand information 0.3 0.2 2 Scoring & • Gather the idea of other Gather the idea of other Ranking Ranking D C nodes that A has contact 0.6 with them: with them: – Second-hand information or ? recommendation Trust (A,D) = ? Trust (B,D) = 0 Trust (C,D) = 0.6 19 20

Scoring and Ranking Generic Trust and Reputation Model Scheme 1 A B • A considers the Gathering 0 0.9 0.3 1 information recommendations according to 0.2 D D hi his opinion about the i i b t th C 0.6 recommenders: 2 Scoring & ? Ranking Ranking Trust (A,D) = ? Trust (A,D) = ? Trust (A,B) = 1 ( , ) Perform Transaction T Trust (A,D) = 1x0=0 t (A D) 1 0 0 Trust (B,D) = 0 Trust (A,D) = 3 Trust (A,D) = Evaluating (0 + 0.54)/2 = (0 + 0.54)/2 = received service 0.27 0.27 T Trust (A,C) = 0.9 t (A C) 0 9 Trust (A,D) = 0.9x0.6=0.54 Trust (C,D) = 0.6 unsatisfied satisfied Update 4 First-hand Punish Punish Reward Reward information 21 22 Some Proposed Models Outline Out e • CONFIDANT • Introduction Sonja Buchegger, Jean-Yves Le Boudec "Performance Analysis of the CONFIDANT Protocol (Cooperation Of Nodes - Performance Analysis of the CONFIDANT Protocol (Cooperation Of Nodes • Security techniques Fairness In Dynamic Ad-hoc NeTworks)."Proceedings of MobiHoc 2002, Lausanne, June 2002. • Trust and reputation systems • CORE • CORE • Generic Trust and Reputation Model Scheme P. Michiardi and R. Molva. CORE: A COllaborative REputation mechanism to enforce • Proposed models for ad hoc and sensor networks node cooperation in Mobile Ad Hoc Networks. Communication and Multimedia – CONFIDANT Security, September, 2002 . – CORE • RFSN – RFSN RFSN S. Ganeriwal and M. Srivastava. Reputation-based framework for high integrity sensor networks. In proceedings of the 2nd ACM workshop on Security of ad hoc and • Problems exist in reputation systems sensor networks (SASN ’04), October 2004 • Summary • Summary 23 24

CONFIDANT Out Outline e • Its Goal is to detect, prevent, and discourage: • Introduction – Selfishness (not forwarding of control messages or data) – Traffic deviation • Security techniques • Advertise many routes • Trust and reputation systems • Advertise routes too often Advertise routes too often • Generic Trust and Reputation Model Scheme • Advertise no routes • Proposed models for ad hoc and sensor networks – Route salvaging, rerouting to avoid a broken although no error has been observed h b b d – CONFIDANT – Lock of error messages, although an error has been observed – CORE ( (and vice versa) ) – RFSN RFSN – Silent route change (tampering with message headers of either • Problems exist in reputation systems control or data packets) • Summary • Summary 25 26 CONFIDANT Protocol CONFIDANT Components • Monitor • Is built on DSR (Dynamic Source Routing) – Directly observes behaviour • Trust Manager • Observes Behaviour – Sends and receives ALARMs – 'Neighbourhood Watch' behaviour that is directly observed, overheard, by the node h d b th d • Reputation System • Reports Behaviour – Node Rating – Share experienced misbehaviour and learn from friends Share experienced misbehaviour and learn from friends • Path Manager P th M • Make decision based on Behaviour – Route management based on Reputation Each node has all of these components locally 27 28