GNUnet

GNUnet is free software for decentralized P2P networks. This framework offers network layer level encryption and resource location. GNUnet peers monitor the behavior of other peers, regarding the use of resources; peers who contribute to the network are rewarded with better service.

The source code has been written in C, but there is an effort with Freeway to produce a compatible version written in Java. Currently GNUnet works under GNU/Linux, BSD, Mac OS X, Solaris and Windows.

It is part of the GNU project.

File sharing

Its main application is anonymity and resistance to censorship, allowing users to publish or obtain information anonymously.

The file sharing service uses the GNUnet anonymous protocol to route requests and responses. The sent request messages are used to search for content and information packets. Depending on the load of the forwarding node, messages are sent from 0 to more nodes. When a node is under "pressure" it abandons requests from its neighboring nodes with a lower internal trust value.

GNUnet offers the option "Friend-to-friend topology" to restrict connections to only the user's trusted nodes. The user's trusted nodes (and so on) can indirectly exchange files with the user's computer, not using its IP address directly.

URIs

GNUnet uses URIs (not approved by IANA). The URI notation has changed over versions of GNUnet. The following notation is used since version 0.7.0.

GNUnet URIs mainly consist of two parts: the module and the module-specific identifier. A GNUnet URI has the form gnunet://module/identifier where module is the name of the module and identifier is the module-specific string.

The ECRS module

Files exchanged with GNUnet are encrypted with ECRS (Encoding for Censorship-Resistant Sharing). The identifier of the ecrs module consists of any of the following chk, sks, ksk or loc followed by a slash and a specific category value.

• chk identifies files, typically: gnunet://ecrs/chk/[hash of the file, using 0-9A-V].[hash of the application, using 0-9A-V].[file size in bytes]
• sks identifies files within the name spaces, typically: gnunet://ecrs/sks/NAMESPACE/IDENTIFICADOR
• ksk identify search requests, typically: gnunet://ecrs/ksk/PALABRA CLAVE[+PALABRA CLAVE]
• loc identifies a data in a specific machine, typically: gnunet://ecrs/loc/PEER/SOLICITUD.TIPO.CLAVE.TAMAÑO

Examples

A type of file sharing with GNUnet pointing to a copy of the text of the GNU GPL license:

gnunet://ecrs/chk/9E4MDN4VULE8KJG6U1C8FKH5HA8C5CHSJTILRTTPGK8MJ6VH
ORERHE68JU8Q0FDTOH1DGLUJ3NLE99N0ML0N9PIBAGKG7MNPBTT6UKG.1I823C58O3L
KS24LLI9KB384LH82LGF9GUQRJHACCUINSCQH36SI4NF88CMAET3T3BHI93D4S0M5CC
6MVDL1K8GFKVBN69Q6T307U6O.17992

Another type of file sharing with GNUnet, pointing to the results of a search with the keyword "gpl":

gnunet://ecrs/ksk/gpl

Chat

Although as a test rather than a full application, a trivial chat feature has been implemented.