GNU's framework for secure peer-to-peer networking

 GNUnet is a framework for secure peer-to-peer networking that does not use any
 centralized or otherwise trusted services. Its high-level goal is to provide a
 strong free software foundation for a global network that provides security
 and in particular respects privacy.
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 GNUnet started with an idea for anonymous censorship-resistant file-sharing,
 but has grown to incorporate other applications as well as many generic
 building blocks for secure networking applications. In particular, GNUnet now
 includes the GNU Name System, a privacy-preserving, decentralized public key
 infrastructure.