Retroshare is a free and open-source peer-to-peer communication and file sharing app based on a friend-to-friend network built by GNU Privacy Guard (GPG).

[8] On 4 November 2014, Retroshare scored 6 out of 7 points on the Electronic Frontier Foundation's secure messaging scorecard, which is now out-of-date.

"[11] Retroshare is an instant messaging and file-sharing network that uses a distributed hash table for address discovery.

[citation needed][14] The degree of anonymity may be improved further by deactivating the DHT and IP/certificate exchange services, making the Retroshare network a real dark net.

[16][better source needed] In 2012, a German Court granted an injunction against a user of Retroshare for sharing copyrighted music files.

In this case, the defendant added the anti-piracy monitoring company as a friend, which allowed him to be traced through aggregation of bad Opsec.