Retroshare

Retroshare

Original author(s)	Robert Fernie
Developer(s)	Cyril Soler Gioacchino Mazzurco
Initial release	2006(2006)
Stable release	0.6.7 / 30 November 2023
Repository	github/RetroShare
Written in	C++
Operating system	Linux,Windows,macOS,Android,FreeBSD,OpenBSD,NetBSD,Haiku
Platform	Cross-platform
Available in	38 languages
List of languages English, Arabic, Bulgarian, Catalan (Spain), Chinese (China), Chinese (Taiwan), Czech, Danish, Dutch, Estonian, Finnish, French, Galician (Spain), German, Greek, Hebrew, Hungarian, Indonesian, Italian, Japanese, Korean, Macedonian, Malayalam, Norwegian Bokmål, Occitan, Polish, Portuguese, Portuguese (Brazil), Portuguese (Portugal), Romanian, Russian, Serbian, Slovenian, Spanish, Swedish, Turkish, Ukrainian, Vietnamese
Type	Anonymous P2P,friend-to-friend,chat,instant messaging,newsgroups,voice over IP,email clientandBBS
License	GNU General Public License
Website	retroshare.cc

Retroshareis afree and open-sourcepeer-to-peercommunication andfile sharingapp based on afriend-to-friendnetwork built byGNU Privacy Guard(GPG).Optionally peers may exchangecertificatesandIP addressesto their friends and vice versa.

History

Retroshare was founded in 2004 by Mark Fernie.An unofficialbuildfor thesingle-board computerRaspberry Pi,named PiShare, was available since 2012.

On 4 November 2014, Retroshare scored 6 out of 7 points on theElectronic Frontier Foundation'ssecure messagingscorecard, which is now out-of-date. It lost a point because there had not been a recent independentcode audit.

In August 2015, Retrosharerepositorywas migrated fromSourceForgetoGitHub.In 2016,Linux Magazinereviewed security gaps in Retroshare and described it as "a brave effort, but in the end, an ineffective one."

Design

Retroshare is aninstant messagingandfile-sharingnetwork that uses adistributed hash tablefor address discovery. Users can communicate indirectly through mutual friends and request direct connections.

Features

Authentication and connectivity

After initial installation, the user generates a pair of (GPG)cryptographic keyswith Retroshare. Afterauthenticationand exchanging anasymmetric key,OpenSSLis used to establish a connection, and forend-to-end encryption.Friends of friends cannot connect by default, but they can see each other, if the users allow it.IPv6was released in November of 2018.

File sharing

It is possible to share folders between friends.File transfer is carried on using a multi-hop swarming system (inspired by the "Turtle Hopping" feature from theTurtle F2Fproject, but implemented differently). In essence, data is only exchanged between friends, although it is possible that the ultimate source and destination of a given transfer are multiple friends apart. A search function performing anonymous multi-hopsearch is another source of finding files in the network.

Files are represented by theirSHA-1hashvalue, andHTTP-compliant file and links may be exported, copied, and pasted into/out of Retroshare to publish their virtual location into the Retroshare network.

Communication

Retroshare offers the following services for communication:

• a privatechat;
• a private mailing system that allows secure communication between known friends and distant friends;
• public and private multi-user chat lobbies;
• aforumsystem allowing both anonymous and authenticated forums, which distributes posts from friends to friends;
• a channel system offers the possibility to auto-download files posted in a given channel to every subscribed peer, similar toRSSfeeds;
• a posted links system, where links to important information can be shared;
• VoIPcalls;
• Video calls(since version 0.6.0);
• TorandI2Pnetworks support, for furtheranonymisation(since version 0.6.0).

User interface

The core of the Retroshare software is based on an offline library, into which two executables are plugged:

• acommand-line interfaceexecutable which offers nearly no control, but it is useful to run "headless" on aserver
• agraphical user interfacewritten inQtis the one most users use. In addition to functions quite common to other file-sharing software, such as a search tab and visualization of transfers, Retroshare gives users the potential to manage their network by collecting optional information about neighbouring friends and visualizing it as a trust matrix or as a dynamic network graph. The appearance can be changed by choosing one of several available style sheets.

Anonymity

Thefriend-to-friendstructure of the Retroshare network makes it difficult to intrude and hardly possible to monitor from an external point of view.The degree of anonymity may be improved further by deactivating theDHTand IP/certificateexchange services, making the Retroshare network a real dark net.

Friends of friends may not connect directly with each other; however, a user may enable the anonymous sharing of files with friends of friends. Search, access, and both upload and download of these files are made by "routing" through a series of friends. This means that communication between the source of data (the up-loader) and the destination of the data (the down-loader) is indirect through mutual friends. Although the intermediary friends cannot determine the original source or ultimate destination, they can see their very next links in the communication chain (their friends). Since the data stream is encrypted, only the original source and ultimate destination are able to see what data is transferred.

Caveats

While Retroshare's encryption makes it virtually impossible for anISPor another external observer to know what one is downloading or uploading, this limitation does not apply to members of the user's Retroshare circle of trust; adding untrusted people to it may be a potential risk.

In 2012, a German Court granted an injunction against a user of Retroshare for sharing copyrighted music files. Retroshare derives its security from the fact that all transfers should go through “trusted friends” whom users add. In this case, the defendant added the anti-piracy monitoring company as a friend, which allowed him to be traced through aggregation of badOpsec.

See also

• Comparison of file-sharing applications

External links

• Official website