A modified BitTorrent protocol for anonymous peer-to-peer file sharingTural Badirkhanli, Amrik Kochhar, Albert Ni, Kuat YessenovTural Badirkhanli, Amrik Kochhar, Albert Ni, Kuat YessenovOutline BitTorrent – Pros and Cons BitTAKA – Anonymous BitTorrent Simulation Possible ImprovementsBitTorrent Pros Efficient because downloaders also act as uploaders Uploading is enforced via “tit-for-tat” based protocolBitTorrent Cons Anonymity – users learn identifying information about their peersbitTAKA Goals Share files using a protocol fundamentally similar to BitTorrent’sProvide anonymity to users of the bitTAKA network Provide anonymity to users of the bitTAKA network In particular, users can share the files they want without learning anything about other users of the network Still be “reasonably” efficientProtocol Outline Requires a trusted tracker to mediate traffic Traffic between peers sharing a file is forwarded through a third-party (called a “Forwarder”) a third-party (called a “Forwarder”)AliceBobBitTAKA ProtocolFrankKyleCircuit for “Bob”?Tracker???6857-grades.txtBob: 6857-grades.txt-List of NamesCircuit for “Bob”?-Forwarding Info-“Bob”-Frank_IP Two-way IP to Name mapping maintained by the tracker Any element of this mapping is NEVER learned by any user Incentive for forwarding is maintained by always having forwarding go both waysProtocol ReviewReview of Goals I Still share files using something similar to the BitTorrent protocol In particular –how is tit-for-tat still enforced?In particular –how is tit-for-tat still enforced?Review of Goals II Provide anonymity to users of the bitTAKA network In particular, can users share the files they want without learning anything about other users of the network?learning anything about other users of the network?Review of Goals III Still be “reasonably” efficient In particular, how do the extra hops affect performance?Flaws Perhaps impractical due to issues with: ScalabilityEfficiencyEfficiency Still need to trust tracker – single point of “trust failure”Potential Practical Improvements Cycle through forwarders before choking a peer Maintain data about each others’ forwarding speeds Distributing tracker routing information1.Assumption of anonymity changes1.Assumption of anonymity changes2. How to discover new routes?Simulation Designed a basic testing framework in Java, able to simulate dozens of peers locally, and propagate messages Intend to model:•Choking algorithm•Choking algorithm• Network delays• Malicious peers and forwarders Performance
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