Trustworthy Distributed Search and Retrieval over the Internet Presented by Yung-Ting Chuang Research conducted in collaboration with Isai Michel Lombera, Louise E. Moser and P. M. Melliar-Smith Supported in part by NSF Grant CNS 10-16103

Overview iTrust Introduction Implementation of iTrust Performance evaluation Conclusion and future work WORLDCOMP’2011 iTrust Yung-Ting Chuang

iTrust vs Centralized Search Engine Nowadays we use centralized search engines (Google, Yahoo, Bing, etc) Benefits Drawbacks iTrust – distributes metadata and request to random participating nodes WORLDCOMP’2011 iTrust Yung-Ting Chuang

Distribution of Metadata Source of Information WORLDCOMP’2011 iTrust Yung-Ting Chuang

Distribution of a Request Source of Information Request Encounters Metadata Requester of Information WORLDCOMP’2011 iTrust Yung-Ting Chuang

Retrieval of Information Source of Information Request Matched Requester of Information WORLDCOMP’2011 iTrust Yung-Ting Chuang

iTrust Implementation WORLDCOMP’2011 iTrust Yung-Ting Chuang

Web Server Foundation cURL - inter-node communication and resource-specific actions Follows HTTP redirects SQLite - stores node, metadata, membership, and resources Rapid deployment Minimal local write privilege Constrains enforcement Session module - tracks and distinguishes users Log module – for debugging and simulation PECL - inter-node search and requests Send POST statement WORLDCOMP’2011 iTrust Yung-Ting Chuang

Application Infrastructure Metadata functions XML Senders: scan the resources and creates an XML list Receivers: scan and insert sources into current node Helper functions: Inserts nodes into the membership Insert keywords into the database Upload or fetch resources Node querying Java jar files Apache Tika packages Apache Lucene packages WordNet dictionary WORLDCOMP’2011 iTrust Yung-Ting Chuang

Public Interface Computer interfaces Human interfaces Handles inter-node communication (ex. queries, resource distribution, and metadata list distribution) Use inbox-type fashion to distribute/read request. Human interfaces Add nodes or metadata keywords Generates requests Provide feedback WORLDCOMP’2011 iTrust Yung-Ting Chuang

Prototype Implementation of iTrust WORLDCOMP’2011 iTrust Yung-Ting Chuang

Prototype Implementation of iTrust WORLDCOMP’2011 iTrust Yung-Ting Chuang

Prototype Implementation of iTrust * Explain what’s the meaning of “hit” and scoring. WORLDCOMP’2011 iTrust Yung-Ting Chuang

Performance Evaluation Assume: All nodes have the same membership set Internet is reliable All nodes has enough memory to store sources Variables: Membership contains n participating nodes Metadata are distributed to m nodes Requests are distributed to r nodes Proportion x of participating nodes are operational WORLDCOMP’2011 iTrust Yung-Ting Chuang

Probabilistic Analysis Probabilities: 1st node has the metadata and is operational: mx No match on 1st trial: 1- mx = n-mx No match on 2nd trial: n-mx-1 No match on rth trial: n-mx-r+1 n n n n-1 n-r+1 WORLDCOMP’2011 iTrust Yung-Ting Chuang

Probabilistic Analysis Probability q of no match on r trials: q = n-mx n-mx-1 … n-mx-r+1 n n-1 n-r+1 Probability p of a match on r trials: p = 1 - n-mx n-mx-1 … n-mx-r+1 , where If mx+r > n, then p = 1 n ≥ mx+r WORLDCOMP’2011 iTrust Yung-Ting Chuang

Simulation Results libCURL - URL transfer library for transferring data Steps our program performed: Clears database Adds nodes Uploads a file and creates metadata Distributes metadata Selects nodes for requests at random If at least one node replies, program returns 1; Else program returns 0 WORLDCOMP’2011 iTrust Yung-Ting Chuang

Performance Evaluation Results WORLDCOMP’2011 iTrust Yung-Ting Chuang

Performance Evaluation Results WORLDCOMP’2011 iTrust Yung-Ting Chuang

Conclusion and Future Work Achieve high probability of match Match remains high even some nodes are subverted We plan to evaluate the effectiveness, efficiency, scalability, and reliability in PlanetLab We are investigating possible attacks on iTrust and countermeasures to such attacks We are investigating other implementations of iTrust based on SMS We plan to make the iTrust source code, tools, documentation, freely available WORLDCOMP’2011 iTrust Yung-Ting Chuang

Questions? Comments? Our iTrust website: http://itrust.ece.ucsb.edu Contact information: Yung-Ting Chuang: ytchuang@ece.ucsb.edu Isai: imichel@ece.ucsb.edu Our project is supported by NSF: CNS 10-16193 WORLDCOMP’2011 iTrust Yung-Ting Chuang