Freenet: A Distributed Anonymous Information Storage and Retrieval System Josh Colvin CIS 590, Fall 2011
What are the goals of Freenet? Anonymity Repudiability Resilience Efficiency Decentralization
Locating Files File Keys – Keyword-signed key (KSK) – Signed-subspace key (SSK) – Content-hash key (CHK) Issues
Architecture Nodes – Data stores – Routing table Requests – File key – Hops-to-live
Data Retrieval A B E D F C
Data Storage Similar algorithm used in retrieval Promotes efficiency and redundancy Protects against attacks
Data Management Data permanency – Dropping unused data Datastore encryption
Network Expansion Adding new nodes Distribution complications Registering in routing tables
Performance Analysis Convergence – Increases as the network operates – Average path length decreases Scalability – Pathlength scales logarithmically – Projected median of ~30 hops at 1,000,000 nodes Fault-Tolerance – Median path length <20 at 30% node failure
Security Primary goal is protecting anonymity Specific threats – File Modification Infeasible for SSK or CHK data – Denial of service attack Hash Cash Datastore partitioning
Goals Recap Anonymity Repudiability Resilience Efficiency Decentralization
Questions?