Onion routing is a technique for anonymous communication over a computer network. In an onion network, messages are encapsulated in layers of encryption, analogous to the layers of an onion. The encrypted data is transmitted through a series of network nodes called "onion routers," each of which "peels" away a single layer, revealing the data's next destination. When the final layer is decrypted, the message arrives at its destination. The sender remains anonymous because each intermediary knows only the location of the immediately preceding and following nodes. While onion routing provides a high level of security and anonymity, there are methods to break the anonymity of this technique, such as timing analysis.
An anonymous P2P communication system is a peer-to-peer distributed application in which the nodes, which are used to share resources, or participants are anonymous or pseudonymous. Anonymity of participants is usually achieved by special routing overlay networks that hide the physical location of each node from other participants.
The Invisible Internet Project (I2P) is an anonymous network layer that allows for censorship-resistant, peer-to-peer communication. Anonymous connections are achieved by encrypting the user's traffic, and sending it through a volunteer-run network of roughly 55,000 computers distributed around the world. Given the high number of possible paths the traffic can transit, a third party watching a full connection is unlikely. The software that implements this layer is called an "I2P router", and a computer running I2P is called an "I2P node". I2P is free and open sourced, and is published under multiple licenses.
A dark net or darknet is an overlay network within the Internet that can only be accessed with specific software, configurations, or authorization, and often uses a unique customized communication protocol. Two typical darknet types are social networks, and anonymity proxy networks such as Tor via an anonymized series of connections.
The Free Haven Project was formed in 1999 by a group of Massachusetts Institute of Technology students with the aim to develop a secure, decentralized system of data storage. The group's work led to a collaboration with the United States Naval Research Laboratory to develop Tor, funded by DARPA.
Tribler is an open source decentralized BitTorrent client which allows anonymous peer-to-peer by default. Tribler is based on the BitTorrent protocol and uses an overlay network for content searching. Due to this overlay network, Tribler does not require an external website or indexing service to discover content. The user interface of Tribler is very basic and focused on ease of use instead of diversity of features. Tribler is available for Linux, Windows, and OS X.
Garlic routing is a variant of onion routing that encrypts multiple messages together to make it more difficult for attackers to perform traffic analysis and to increase the speed of data transfer.
An anonymizer or an anonymous proxy is a tool that attempts to make activity on the Internet untraceable. It is a proxy server computer that acts as an intermediary and privacy shield between a client computer and the rest of the Internet. It accesses the Internet on the user's behalf, protecting personal information of the user by hiding the client computer's identifying information such as IP addresses. Anonymous proxy is the opposite of transparent proxy, which sends user information in the connection request header.
TorChat was a peer-to-peer anonymous instant messenger that used Tor onion services as its underlying network. It provided cryptographically secure text messaging and file transfers. The characteristics of Tor's onion services ensure that all traffic between the clients is encrypted and that it is very difficult to tell who is communicating with whom and where a given client is physically located.
Tor, short for The Onion Router, is free and open-source software for enabling anonymous communication. It directs Internet traffic via a free, worldwide, volunteer overlay network that consists of more than seven thousand relays.
Metadata removal tool or metadata scrubber is a type of privacy software built to protect the privacy of its users by removing potentially privacy-compromising metadata from files before they are shared with others, e.g., by sending them as e-mail attachments or by posting them on the Web.
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). Optionally peers may exchange certificates and IP addresses to their friends and vice versa.
Digital privacy is often used in contexts that promote advocacy on behalf of individual and consumer privacy rights in e-services and is typically used in opposition to the business practices of many e-marketers, businesses, and companies to collect and use such information and data. Digital privacy can be defined under three sub-related categories: information privacy, communication privacy, and individual privacy.
GlobaLeaks is an open-source, free software intended to enable secure and anonymous whistleblowing initiatives.
SecureDrop is a free software platform for secure communication between journalists and sources (whistleblowers). It was originally designed and developed by Aaron Swartz and Kevin Poulsen under the name DeadDrop. James Dolan also co-created the software.
Tor2web is a software project to allow Tor hidden services to be accessed from a standard browser without being connected to the Tor network. It was created by Aaron Swartz and Virgil Griffith.
Roger Dingledine is an American computer scientist known for having co-founded the Tor Project. A student of mathematics, computer science, and electrical engineering, Dingledine is also known by the pseudonym arma. As of December 2016, he continues in a leadership role with the Tor Project, as a project Leader, Director, and Research Director.
The Torist was a literary journal first released in late 2015, published on the Tor anonymity network. It features short stories, essays and poetry. One of the reasons for publishing on Tor was to return to the idea of rummaging through antiquarian shops – "It gets back to the time when you had to find The Evergreen Review in the stacks at the vintage bookstore" – and the zine can only be accessed through Tor, a dark web site. Its founders are the pseudonymous G.M.H., named after the reclusive 19th-century poet Gerard Manley Hopkins, and Prof. Robert W. Gehl, who is a communication professor focusing on new media at the University of Utah. The two met on the dark-net social network Galaxy, and started collaborating in 2014, taking two years to produce the first issue of the journal. Submissions are made through the anonymous and open-source GlobaLeaks platform — intended for whistleblowing. The founders hope this anonymity can bolster creativity among submissions, and wish to show that anonymity online isn't only for illicit activities.
Riffle is an anonymity network developed by researchers at MIT and EPFL as a response to the problems of the Tor network.
