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{{short description|Peer-to-peer Internet platform for censorship-resistant communication}}
:''For other uses, see ]''
{{other uses|Freenet (disambiguation)}}
{{use dmy dates |date=February 2022}}
{{Infobox software
| title =
| name = Freenet
| logo = Freenet logo.svg
| logo caption =
| screenshot = The_welcome_page_of_Freenet_Hyphanet.png
| caption = FProxy index page (Freenet 0.7)
| collapsible =
| author =
| developer = <ref name="People">{{cite web| title = People| url = https://freenetproject.org/people.html| date = 22 September 2008| publisher = Freenet: The Free Network official website| access-date = 31 May 2014| url-status = dead| archive-url = https://web.archive.org/web/20130921053414/https://freenetproject.org/people.html| archive-date = 21 September 2013}}</ref>
| released = {{start date and age|2000|3}} <!-- {{Start date|2000|03|DD|df=yes/no}} -->
| discontinued = No
| latest release version = {{wikidata|property|preferred|references|edit|Q540|P348|P548=Q2804309}}
| latest release date = {{wikidata|qualifier|preferred|single|Q540|P348|P548=Q2804309|P577}}
| latest preview version = {{wikidata|property|preferred|references|edit|Q540|P348|P548=Q51930650}}
| latest preview date = {{wikidata|qualifier|preferred|single|Q540|P348|P548=Q51930650|P577}}
| repo = https://github.com/hyphanet/fred
| programming language = ]
| operating system = ]: ] (], ], ], ]), ]
| platform = ]
| size =
| language = English, French, Italian, German, Dutch, Spanish, Portuguese, Swedish, Norwegian, Chinese, Russian<ref> {{Webarchive|url=https://web.archive.org/web/20180207061812/https://github.com/freenet/fred/tree/master/src/freenet/l10n |date=7 February 2018 }}, ''GitHub: Freenet''.</ref>
| language count = <!-- DO NOT include this parameter unless you know what it does -->
| language footnote =
| genre = ], ], ], ], ], ]
| license = GNU General Public License version 3 only
| website = {{URL|https://www.hyphanet.org}}
| standard =
| AsOf =
| logo_alt = Logo of Freenet
| screenshot_alt = Screenshot of Freenet 0.7.5
}}
{{File sharing sidebar}}
'''Hyphanet''' (until mid-2023: '''Freenet'''<ref name="Hyphanet"></ref>) is a ] platform for ]-resistant, ] communication. It uses a decentralized ] to keep and deliver information, and has a suite of ] for publishing and communicating on the Web without fear of censorship.<ref name="What is Freenet?"> {{webarchive|url=https://web.archive.org/web/20110916012340/https://freenetproject.org/whatis.html |date=16 September 2011 }}, ''Freenet: The Free network official website''.</ref><ref name="Peers in a Client/Server World, 2005">Taylor, Ian J. ''From P2P to Web Services and Grids: Peers in a Client/Server World''. London: Springer, 2005.</ref>{{rp|151}} Both Freenet and some of its associated tools were originally designed by ], who defined Freenet's goal as providing ] on the Internet with strong anonymity protection.<ref name="Time">{{cite magazine|url=http://www.time.com/time/magazine/article/0,9171,997286,00.html|archive-url=https://web.archive.org/web/20080708213917/http://www.time.com/time/magazine/article/0,9171,997286,00.html|url-status=dead|archive-date=8 July 2008|title=The Infoanarchist|last=Cohen|first=Adam|date=26 June 2000|magazine=] |access-date=18 December 2011}}</ref><ref name="The Guardian-Beckett2009">{{cite news |url=https://www.theguardian.com/technology/2009/nov/26/dark-side-internet-freenet |title=The dark side of the internet |last=Beckett |first=Andy |date=26 November 2009 |newspaper=] |access-date=26 November 2009 |archive-date=8 September 2013 |url-status=live |archive-url=https://web.archive.org/web/20130908073158/http://www.theguardian.com/technology/2009/nov/26/dark-side-internet-freenet }}</ref><ref>{{cite web |url=http://blog.locut.us/2009/11/26/the-guardian-writes-about-freenet/ |title=The Guardian writes about Freenet (Ian Clarke's response) |url-status=dead |archive-date=19 May 2014 |archive-url=https://web.archive.org/web/20140519101142/http://blog.locut.us/2009/11/26/the-guardian-writes-about-freenet/ }}</ref>


The distributed data store of Freenet is used by many third-party programs and plugins to provide ] and media sharing,<ref name="sone">{{cite web|url = http://draketo.de/licht/freie-software/freenet/sone-pseudonymes-microblogging|title = Sone: Pseudonymes Microblogging über Freenet|access-date = 15 September 2015|archive-date = 5 October 2015|archive-url = https://web.archive.org/web/20151005053905/http://draketo.de/licht/freie-software/freenet/sone-pseudonymes-microblogging|url-status = live}}, German article, 2010</ref> anonymous and decentralised version tracking,<ref name="infocalypse">{{cite web |url=https://www.mercurial-scm.org/Infocalypse |title=Infoclypse |department=Wiki |website=] |access-date=2 December 2021 |archive-date=3 November 2021 |archive-url=https://web.archive.org/web/20211103010527/https://www.mercurial-scm.org/Infocalypse |url-status=live }}</ref> blogging,<ref name="floghelper">{{cite web|url=https://github.com/freenet/plugin-FlogHelper-staging|title=Flog Helper: Easy Blogging over Freenet|website=]|date=7 February 2019|access-date=16 December 2011|archive-date=5 February 2022|archive-url=https://web.archive.org/web/20220205041917/https://github.com/freenet/plugin-FlogHelper|url-status=live}}</ref> a generic ] for decentralized ],<ref name="weboftrust">{{cite web|url=http://wiki.freenetproject.org/WoT|title=Web of Trust |date=7 February 2019|access-date=15 September 2015|archive-date=8 December 2015|archive-url=https://web.archive.org/web/20151208180619/https://wiki.freenetproject.org/WoT|url-status=live}}</ref><ref>{{Cite web |title=Web Of Trust |url=https://github.com/hyphanet/wiki/Web-Of-Trust |access-date=2024-10-13 |website=GitHub |language=en}}</ref> Shoeshop for using Freenet over ],<ref name="shoeshop">Freenet over Sneakernet. Freenet Key: USK@MYLAnId-ZEyXhDGGbYOa1gOtkZZrFNTXjFl1dibLj9E,Xpu27DoAKKc8b0718E-ZteFrGqCYROe7XBBJI57pB4M,AQACAAE/Shoeshop/2/</ref> and many more.
'''Freenet''' is a decentralized ]-resistant ] ]. Freenet works by pooling the contributed ] and storage space of member computers to allow users to ] publish or retrieve various kinds of information. Freenet uses a kind of ] similar to a ] to locate peers' data.


==History==
Freenet is currently under development, and a ''version 1.0'' has not yet been released. Freenet is considered by many to be fundamentally different from other peer-to-peer networks; it is still somewhat more difficult to use and slower, and it does not have integrated search functionality. Currently, Freenet cannot be used to create or distribute dynamic content, such as content that utilizes databases and scripting. According to the Freenet Project group, such tradeoffs are expected since Freenet's primary goals are neither ease-of-use nor performance. Unlike other ] networks, Freenet is primarily intended to combat censorship and allow people to communicate freely and with near-total anonymity.
The origin of Freenet can be traced to Ian Clarke's student project at the ], which he completed as a graduation requirement in the summer of 1999.<ref>{{cite news| url = https://www.nytimes.com/2000/05/10/business/cyberspace-programmers-confront-copyright-laws.html| title = Cyberspace Programmers Confront Copyright Laws| first = John| last = Markoff| work = ]| date = 10 May 2000| access-date = 19 February 2017| archive-date = 17 February 2017| archive-url = https://web.archive.org/web/20170217084607/http://www.nytimes.com/2000/05/10/business/cyberspace-programmers-confront-copyright-laws.html| url-status = live}}</ref><ref>{{cite news | url=http://news.bbc.co.uk/2/hi/science/nature/1216486.stm | work=BBC News | title=Coders prepare son of Napster | date=12 March 2001 | access-date=1 June 2014 | archive-date=4 January 2014 | archive-url=https://web.archive.org/web/20140104024058/http://news.bbc.co.uk/2/hi/science/nature/1216486.stm | url-status=live }}</ref><ref>{{cite news | url=http://www.cnn.com/2005/TECH/12/19/internet.freedom/index.html?iref=allsearch | publisher=CNN | title=Fighting for free speech on the Net | date=19 December 2005 | access-date=1 June 2014 | archive-date=2 June 2014 | archive-url=https://web.archive.org/web/20140602200717/http://www.cnn.com/2005/TECH/12/19/internet.freedom/index.html?iref=allsearch | url-status=live }}</ref> Ian Clarke's resulting unpublished report "A distributed decentralized information storage and retrieval system" (1999) provided foundation for the seminal paper written in collaboration with other researchers, "Freenet: A Distributed Anonymous Information Storage and Retrieval System" (2001).<ref>Ian Clarke. {{Webarchive|url=https://web.archive.org/web/20120316102156/https://freenetproject.org/papers/ddisrs.pdf |date=16 March 2012 }}. Unpublished report, Division of Informatics, University of Edinburgh, 1999.</ref><ref name="Freenet: A Distributed Anonymous Information Storage and Retrieval System">Ian Clarke, Oskar Sandberg, Brandon Wiley, and Theodore W. Hong. {{Webarchive|url=https://web.archive.org/web/20150404062238/http://www.cs.cornell.edu/people/egs/615/freenet.pdf |archive-url=https://web.archive.org/web/20030330213648/http://www.cs.cornell.edu/people/egs/615/freenet.pdf |archive-date=2003-03-30 |url-status=live |date=4 April 2015 }}. In: Proceedings of the International Workshop on Designing Privacy Enhancing Technologies: Design Issues in Anonymity and Unobservability. New York, NY: Springer-Verlag, 2001, p. 46-66.</ref> According to ], it became one of the most frequently cited ] articles in 2002.<ref>{{cite conference |conference=International Workshop on Design Issues in Anonymity and Unobservability |book-title=Designing Privacy Enhancing Technologies |title=Freenet: A Distributed Anonymous Information Storage and Retrieval System |first1=Ian |last1=Clarke |first2=Oskar |last2=Sandberg |first3=Brandon |last3=Wiley |first4=Theodore W. |last4=Hong |date=28 February 2001 |publisher=Springer-Verlag |pages=46–66 |isbn=978-3-540-41724-8 |doi=10.1007/3-540-44702-4_4 |url=http://www.facweb.iitkgp.ac.in/~niloy/COURSE/Autumn2010/UC/Resource/freenet1-big.pdf |archive-url=https://web.archive.org/web/20230603205950/http://www.facweb.iitkgp.ac.in/~niloy/COURSE/Autumn2010/UC/Resource/freenet1-big.pdf |archive-date=3 June 2023 |url-status=live }}</ref>


Freenet can provide anonymity on the Internet by storing small encrypted snippets of content distributed on the computers of its users and connecting only through intermediate computers which pass on requests for content and sending them back without knowing the contents of the full file. This is similar to how ] on the Internet route ] without knowing anything about files{{px2}}{{mdash}}{{hsp}}except Freenet has caching, a layer of strong encryption, and no reliance on ].<ref name="Freenet: A Distributed Anonymous Information Storage and Retrieval System" /> This allows users to publish anonymously or retrieve various kinds of information.<ref name="Peers in a Client/Server World, 2005" />{{rp|152}}
== Purpose ==
Although many nations censor communications to different extents, they all share one commonality in that a body must decide what information to censor and what information to allow. What may be acceptable to one group of people may be considered offensive or even dangerous to another. Freenet is a network which, putatively, removes the possibility of any group imposing their beliefs or values on any other. In essence nobody is allowed to decide what is acceptable for anybody else. Tolerance for each others' values is encouraged and failing that, the user is asked to ] to content which opposes his or her views.


===Release history===
== Technical design ==
]
The type of ] protocol Freenet uses is ]. While the idea emerged independently, Freenet's routing algorithm is similar to that employed by ]s (DHTs). The main differences are that Freenet nodes do not have fixed specialisations, and the routing algorithm is heuristic in nature. Therefore, it does not guarantee that it will find a given piece of data. Freenet can also be viewed as a ].
Freenet has been under continuous development since 2000.


Freenet 0.7, released on 8 May 2008, is a major re-write incorporating a number of fundamental changes. The most fundamental change is support for ] operation. Version 0.7 offered two modes of operation: a mode in which it connects only to friends, and an opennet-mode in which it connects to any other Freenet user. Both modes can be run simultaneously. When a user switches to pure darknet operation, Freenet becomes very difficult to detect from the outside. The ] created for the darknet mode allows communication over restricted routes as commonly found in ], as long as these connections follow a ] structure.<ref>Singh, Munindar P. The Practical Handbook of Internet Computing. Boca Raton, Fl.: Chapman & Hall, 2005.</ref>{{rp|815–816}} Other modifications include switching from ] to ], which allows ] along with faster transmission of messages between peers in the network.<ref>{{cite news|last1=Ihlenfeld|first1=Jens|title=Freenet 0.7 soll globales Darknet schaffen|url=http://www.golem.de/0604/44448.html|access-date=17 September 2015|publisher=Golem|date=4 April 2006|archive-date=5 October 2015|archive-url=https://web.archive.org/web/20151005170034/http://www.golem.de/0604/44448.html|url-status=live}}</ref>
The Freenet ] network is designed to be highly survivable, with all internal processes completely anonymized and decentralized across the network. The system has no central servers, is ], and is not subject to the control of any one individual or organization. Even the designers of Freenet do not have any control over the overall system. The system is designed so that information stored in the system is encrypted and replicated across a large number of continuously-changing anonymized computers around the world. It is extremely difficult for an attacker to find out which participants are hosting a given file, since the contents of each file are encrypted, and can also be broken into sections that are distributed over many different computers. Even the participants themselves don't know what they are storing.


Freenet 0.7.5, released on 12 June 2009, offers a variety of improvements over 0.7. These include reduced memory usage, faster insert and retrieval of content, significant improvements to the FProxy web interface used for browsing freesites, and a large number of smaller bugfixes, performance enhancements, and usability improvements. Version 0.7.5 also shipped with a new version of the Windows installer.<ref> {{Webarchive|url=https://web.archive.org/web/20141129011927/https://freenetproject.org/news.html#freenet-0-7-5-released |date=29 November 2014 }}, last accessed 17 September 2015</ref>
The end goal of the Freenet network is to store documents and allow them to be retrieved later by an associated key, as is now possible with protocols such as ]. The network is implemented as a number of nodes that pass messages among themselves peer-to-peer. Typically, a host computer on the network will run the software that acts as a node, and it will connect to other hosts running that same software to form a large distributed network of peer nodes. Certain nodes will be end user nodes, from which documents will be requested and presented to the human user. But these nodes communicate with each other and with intermediate routing nodes identically&mdash;there are no dedicated "clients" or "servers" on the network.


As of build 1226, released on 30 July 2009, features that have been written include significant security improvements against both attackers acting on the network and physical seizure of the computer running the node.<ref> {{Webarchive|url=https://web.archive.org/web/20141129011927/https://freenetproject.org/news.html#build1226 |date=29 November 2014 }}, last accessed 17 September 2015</ref>
The Freenet protocol is intended to be implemented on a network with a complex network topology, such as the Internet (]). Each node knows only about some number of other nodes that it can reach directly (its conceptual "neighbors"), but any node can be a neighbor to any other; there is no hierarchy or other structure. Each document (or other message such as a document request) in Freenet is routed through the network by passing from neighbor to neighbor until reaching its destination. As each node passes a document to its neighbor, it does not know or care whether its neighbor is just another routing node forwarding information on behalf of another, whether it is the source of the document being passed, or whether it is a user node that will present the document to an end user. This is intentional, so that anonymity of both users and publishers can be protected.


As of build 1468, released on 11 July 2015, the Freenet core stopped using the ] database and laid the foundation for an efficient interface to the Web of Trust plugin which provides spam resistance.<ref> {{Webarchive|url=https://web.archive.org/web/20141129011927/https://freenetproject.org/news.html#20150711-1468-release |date=29 November 2014 }} 2015</ref>
Each node maintains a data store containing documents associated with keys, and a routing table associating nodes with records of their performance in retrieving different keys.


Freenet has always been free software, but until 2011 it required users to install ]. This problem was solved by making Freenet compatible with ], a free and open source implementation of the Java Platform.
To find a document in the network given a key, a user sends a message to a node (probably one running on the same machine as the client program) requesting the document, providing it with the key. If the document is not found in the local data store, the node then finds the node in its routing table that it thinks will be able to locate the key most quickly, and forwards the request to that node, remembering that it has done so. Note that this is a change from the behavior of earlier versions of Freenet nodes: it represents the "Next Generation Routing" protocol. The old behavior was to remember which keys were retrieved from what nodes, and to route based on which node gave us the key closest to the one we were looking for. The effect is largely the same, but NGR, as it is called, results in better overall performance.


On 11 February 2015, Freenet received the SUMA-Award for "protection against total surveillance".<ref name=suma_award> {{Webarchive|url=https://web.archive.org/web/20150320201527/http://suma-awards.de/en/index.html |date=20 March 2015 }}, 11 February 2015.</ref><ref name=suma_award_recording> {{Webarchive|url=https://web.archive.org/web/20150905121823/https://www.youtube.com/watch?v=dZpsBSPsHDI&app=desktop |date=5 September 2015 }}, published on 14 April 2015.</ref><ref name=suma_award_heise> {{Webarchive|url=https://web.archive.org/web/20150924152732/http://www.heise.de/newsticker/meldung/SUMA-Award-fuer-das-Freenet-Project-2548577.html |date=24 September 2015 }} Jo Bager in Heise online, 2015</ref>
The node to which the request was forwarded repeats the process until either the key is found or the request passes through a set maximum of nodes, known as the "Hops To Live" value. Along the route, if a node is visited more than once (and it will know this because it remembered forwarding the request the first time) then that node cuts off the loop by sending a message to the node that sent it the second request telling it to try the next-best choice, then the next-next-best, and so on.


==Features and user interface==
Eventually, either the document is found or the hop limit is exceeded. The terminal node sends a reply that works its way back to the originator along the route specified by the intermediate nodes' records of pending requests. The intermediate nodes may choose to cache the document along the way. Besides saving bandwidth, this also makes documents harder to censor as there is no one "source node."
Freenet served as the model for the Japanese peer to peer file-sharing programs ], ] and ], but this model differs from p2p networks such as ] and ]. Freenet separates the underlying network structure and protocol from how users interact with the network; as a result, there are a variety of ways to access content on the Freenet network. The simplest is via FProxy, which is integrated with the node software and provides a web interface to content on the network. Using FProxy, a user can browse freesites (websites that use normal ] and related tools, but whose content is stored within Freenet rather than on a traditional web server). The web interface is also used for most configuration and node management tasks. Through the use of separate applications or plugins loaded into the node software, users can interact with the network in other ways, such as forums similar to web forums or Usenet or interfaces more similar to traditional P2P "filesharing" interfaces.


While Freenet provides an ] interface for browsing freesites, it is not a ] for the ]; Freenet can be used to access only the content that has been previously inserted into the Freenet network. In this way, it is more similar to ] than to anonymous proxy software like ].
Essentially, the same path-finding process is used to insert a document into the network: a request for the nonexistent document is made, and once it fails, the document is sent along the same path as the request. This ensures that documents are inserted into the network in the same place as requests will look for it. If the initial request doesn't fail, then the data already existed, and the insert "collides."


Freenet's focus lies on ] and anonymity. Because of that, Freenet acts differently at certain points that are (directly or indirectly) related to the anonymity part. Freenet attempts to protect the anonymity of both people inserting data into the network (uploading) and those retrieving data from the network (downloading). Unlike file sharing systems, there is no need for the uploader to remain on the network after uploading a file or group of files. Instead, during the upload process, the files are broken into chunks and stored on a variety of other computers on the network. When downloading, those chunks are found and reassembled. Every node on the Freenet network contributes storage space to hold files and bandwidth that it uses to route requests from its peers.
Initially, each node has no information about the performance of the other nodes it knows about. This means that routing of requests will be essentially random. But since different nodes have different randomness, they will disagree about where to send a request, given a key. So the data in a newly-started Freenet will therefore be distributed somewhat randomly.


As a direct result of the anonymity requirements, the node requesting content does not normally connect directly to the node that has it; instead, the request is routed across several intermediaries, none of which know which node made the request or which one had it. As a result, the total bandwidth required by the network to transfer a file is higher than in other systems, which can result in slower transfers, especially for infrequently accessed content.
As more documents are inserted by the same node, they will begin to cluster with data items whose keys are similar, because the same routing rules are used for all of them. More importantly, as data items and requests from different nodes "cross paths", they will begin to share clustering information as well.


Since version 0.7, Freenet offers two different levels of security: opennet and darknet. With opennet, users connect to arbitrary other users. With darknet, users connect only to "friends" with whom they previously exchanged ], named node-references. Both modes can be used together.
The result is that the network will self-organize into a distributed, clustered structure where nodes tend to hold data items that are close together in key space. There will probably be multiple such clusters throughout the network, any given document being replicated numerous times, depending on how much it is used. This is a kind of "spontaneous symmetry breaking", in which an initially symmetric state (all nodes being the same, with random initial keys for each other) leads to a highly asymmetric situation, with nodes coming to specialize in data that has closely related keys.


==Content==
There are forces which tend to cause clustering (shared closeness data spreads throughout the network), and forces that tend to break up clusters (local caching of commonly used data). These forces will be different depending on how often data is used, so that seldom-used data will tend to be on just a few nodes which specialize in providing that data, and frequently used items will be spread widely throughout the network. This automatic mirroring counteracts the times when ] becomes overloaded, and due to a mature network's intelligent routing a network of size n should only require log(n) time to retrieve any given document. Freenet does not employ broadcast searches as used by ] and other similar file sharing protocols.
Freenet's founders argue that true freedom of speech comes only with true anonymity and that the beneficial uses of Freenet outweigh its negative uses.<ref name="philosophy">{{cite web|url=https://freenetproject.org/philosophy.html|title=The Philosophy behind Freenet|access-date=20 December 2010|archive-url=https://web.archive.org/web/20110430201105/http://freenetproject.org/philosophy.html|archive-date=30 April 2011|url-status=dead}}</ref> Their view is that free speech, in itself, is not in contradiction with any other consideration—the information is not the crime. Freenet attempts to remove the possibility of any group imposing its beliefs or values on any data. Although many states censor communications to different extents, they all share one commonality in that a body must decide what information to censor and what information to allow. What may be acceptable to one group of people may be considered offensive or even dangerous to another. In essence, the purpose of Freenet is to ensure that no one is allowed to decide what is acceptable.


Reports of Freenet's use in authoritarian nations is difficult to track due to the very nature of Freenet's goals. One group, ''Freenet China'', used to introduce the Freenet software to ] users starting from 2001 and distribute it within China through e-mails and on disks after the group's website was blocked by the Chinese authorities on the mainland. It was reported that in 2002 ''Freenet China'' had several thousand dedicated users.<ref>Damm, Jens, and Simona Thomas. ''Chinese Cyberspaces Technological Changes and Political Effects''. London: Routledge, 2006.</ref>{{rp|70–71}} However, Freenet opennet traffic was blocked in China around the 2010s.<ref>{{Cite web |title=Hyphanet |url=https://www.hyphanet.org/ |access-date=2024-07-03 |website=www.hyphanet.org |language=en}}</ref>{{Citation needed|reason=This sounds plausible but would benefit from a source|date=November 2017}}
One thing to keep in mind is that keys are ]es, hence there is no notion of ] when speaking of key closeness. Therefore there will be no correlation between key closeness and similar popularity of data as there might be if keys did exhibit some semantic meaning, thus avoiding bottlenecks caused by popular subjects.


==Technical design==
There are two main varieties of keys in use on Freenet, the ] (CHK) and the ] (SSK).
{{See also|Cryptography}}


The Freenet ] network stores documents and allows them to be retrieved later by an associated key, as is now possible with protocols such as ]. The network is designed to be highly survivable. The system has no central servers and is not subject to the control of any one individual or organization, including the designers of Freenet. The codebase size is over 192,000 ].<ref>{{cite video|url=https://www.youtube.com/watch?v=HfuZJVpNWR4&feature=youtu.be&list=TLPQMjMwOTIwMjDcsXnGLhV7-Q&t=635| archive-url=https://ghostarchive.org/varchive/youtube/20211211/HfuZJVpNWR4| archive-date=11 December 2021 | url-status=live|title=The dark side of the web -- exploring darknets | publisher=]|location =]|first=Kyle|last=Terry|author-link=Kyle Terry}}{{cbignore}}</ref> Information stored on Freenet is distributed around the network and stored on several different nodes. Encryption of data and relaying of requests makes it difficult to determine who inserted content into Freenet, who requested that content, or where the content was stored. This protects the anonymity of participants, and also makes it very difficult to censor specific content. Content is stored encrypted, making it difficult for even the operator of a node to determine what is stored on that node. This provides ]; which, in combination with request relaying, means that ] laws that protect service providers may also protect Freenet node operators. When asked about the topic, Freenet developers defer to the EFF discussion which says that not being able to filter anything is a safe choice.<ref>{{cite web|url=https://emu.freenetproject.org/pipermail/chat/2009-February/001872.html|archive-url=https://web.archive.org/web/20160303232303/https://emu.freenetproject.org/pipermail/chat/2009-February/001872.html|url-status=dead|archive-date=3 March 2016|last=Toseland|first=Matthew |title=Does Freenet qualify for DMCA Safe Harbor? |access-date=27 January 2013}}</ref><ref>{{cite web|url=https://www.eff.org/wp/iaal-what-peer-peer-developers-need-know-about-copyright-law|title=IAAL*: What Peer-to-Peer Developers Need to Know about Copyright Law|access-date=15 September 2015|date=10 January 2006|archive-date=30 November 2015|archive-url=https://web.archive.org/web/20151130021911/https://www.eff.org/wp/iaal-what-peer-peer-developers-need-know-about-copyright-law|url-status=live}}</ref>
A CHK is an ] hash of a document and thus a node can check that the document returned is correct by hashing it and checking the digest against the key. This key contains the meat of the data on freenet. It carries all the binary data building blocks for the content to be delivered to the client for reassembly and decryption. The CHK is unique by nature and provides tamperproof content. A hostile node altering the data under a CHK will immediately be detected by the next node or the client. CHKs also reduce the redundancy of data since the same data will have the same CHK.


===Distributed storage and caching of data===
SSKs are based on ]. Currently Freenet uses the ] system as its ]. Documents inserted under SSKs are signed by the inserter, and this signature can be verified by every node to ensure that the data is not tampered with. SSKs can be used to establish a verifiable ] identity on Freenet, and allow for documents to be updated securely by the person who inserted them. A subtype of the SSK is the Keyword Signed Key, or KSK, in which the key pair is generated in a standard way from a simple human-readable string. Inserting a document using a KSK allows the document to be retrieved and decrypted if and only if the requester knows the human-readable string; this allows for more convenient (but less secure) ]s for users to refer to.
Like ], ] and ], Freenet not only transmits data between nodes but actually stores them, working as a huge distributed cache. To achieve this, each node allocates some amount of disk space to store data; this is configurable by the node operator, but is typically several GB (or more).


Files on Freenet are typically split into multiple small blocks, with duplicate blocks created to provide ]. Each block is handled independently, meaning that a single file may have parts stored on many different nodes.
== Scalability ==


Information flow in Freenet is different from networks like ] or ]; in Freenet:
A ] network is said to be scalable if the performance of the network does not deteriorate even for very large network sizes. The scalability of Freenet is being evaluated, but similar architectures have been shown to scale logarithmically .


# A user wishing to share a file or update a freesite "inserts" the file "to the network"
== History ==
# After "insertion" is finished, the publishing node is free to shut down, because the file is stored in the network. It will remain available for other users whether or not the original publishing node is online. No single node is responsible for the content; instead, it is replicated to many different nodes.


Two advantages of this design are high reliability and anonymity. Information remains available even if the publisher node goes offline, and is anonymously spread over many hosting nodes as encrypted blocks, not entire files.
Freenet is an enhanced ] / ] implementation of the system described by ]'s July ] paper "A distributed decentralized information storage and retrieval system", written while Clarke was a student at the University of Edinburgh. Shortly after the publication of this paper, Clarke and a small number of volunteers began work on what became Freenet. By March ] version 0.1 of Freenet was ready for release. Since March 2000 Freenet has been extensively reported on in the press, albeit primarily due to its implications for ] rather than for its wider aim of freedom of communication.


The key disadvantage of the storage method is that no one node is responsible for any chunk of data. If a piece of data is not retrieved for some time and a node keeps getting new data, it will drop the old data sometime when its allocated disk space is fully used. In this way Freenet tends to 'forget' data which is not retrieved regularly (see also ]).
Freenet has been developed via a collaborative, open source, methodology. Clarke, originally from Ireland, worked with individuals from many other countries, in a distributed manner utilizing the Internet. Not only is Freenet itself distributed, decentralized Internet software, but the method used to develop it is also distributed and decentralized.


While users can insert data into the network, there is no way to delete data. Due to Freenet's anonymous nature the original publishing node or owner of any piece of data is unknown. The only way data can be removed is if users don't request it.
Reports of Freenet's use in authoritarian nations is difficult to track due to the very nature of Freenet's goals. One group, ], has translated the Freenet software to Chinese and is distributing it within China on CD and floppy disk.


===Network===
According to ], Ian Clarke's "Freenet: A Distributed Anonymous Information Storage and Retrieval System" was the most cited ] paper of 2000.
Typically, a host computer on the network runs the software that acts as a node, and it connects to other hosts running that same software to form a large distributed, variable-size network of peer nodes. Some nodes are end user nodes, from which documents are requested and presented to human users. Other nodes serve only to route data. All nodes communicate with each other identically – there are no dedicated "clients" or "servers". It is not possible for a node to rate another node except by its capacity to insert and fetch data associated with a key. This is unlike most other P2P networks where node administrators can employ a ratio system, where users have to share a certain amount of content before they can download.


Freenet may also be considered a ].
One analysis{{ref|2}} of Freenet files conducted in the year 2000 claimed that the top 3 types of files contained in Freenet were text (37%), audio (21%), and images (14%). 59% of all the text files were drug-related, 71% of all audio files were rock music, and 89% of all images were pornographic. It is important to note the fundamental design of Freenet makes accurate analysis of its content difficult. This analysis was done several years ago from within the ], and the network has been vastly changed and expanded since it was published and many different types of content have been added.


The Freenet protocol is intended to be used on a network of complex topology, such as the Internet (]). Each node knows only about some number of other nodes that it can reach directly (its conceptual "neighbors"), but any node can be a neighbor to any other; no hierarchy or other structure is intended. Each message is routed through the network by passing from neighbor to neighbor until it reaches its destination. As each node passes a message to a neighbor, it does not know whether the neighbor will forward the message to another node, or is the final destination or original source of the message. This is intended to protect the anonymity of users and publishers.
== Current development ==
Freenet is currently undergoing a major re-write incorporating a number of fundamental changes. Version 0.7 of Freenet aims to create a scalable ], where users only connect directly to other users they know and trust. The purpose of this change is to protect users who may be placed at risk simply by using the software, irrespective of what they are using it for. In the new model, users will choose who they connect to, and only those users will know that they are running the software. Previous darknets, such as ], have been limited to relatively small disconnected networks. The core innovation in Freenet 0.7 will be to allow a globally scalable darknet, capable of supporting millions of users. This is made possible by the fact that human relationships tend to form ]s, a property that can be exploited to find short paths between any two people. The work is based on a speech given at ] by ] and Swedish mathematician ].


Each node maintains a data store containing documents associated with keys, and a routing table associating nodes with records of their performance in retrieving different keys.
Other modifications include switching from ] to ], which allows ] along with faster transmission of messages between peers in the network. While previously Freenet only supported the insertion and retrieval of information, Freenet 0.7 will support new modes of usage including the real-time broadcast of messages. Features planned for later versions include anonymous "channels" to a particular node allowing for dynamic content, searching, and ]. Applications of this range from ] to ]-feeds.


===Protocol===
It is anticipated that Freenet 0.7 will be released by Christmas 2005.
]


The Freenet protocol uses a ] protocol, similar to ]s. The routing algorithm changed significantly in version 0.7. Prior to version 0.7, Freenet used a ] algorithm where each node had no fixed location, and routing was based on which node had served a key closest to the key being fetched (in version 0.3) or which is estimated to serve it faster (in version 0.5). In either case, new connections were sometimes added to downstream nodes (i.e. the node that answered the request) when requests succeeded, and old nodes were discarded in least recently used order (or something close to it). Oskar Sandberg's research (during the development of version 0.7) shows that this "path folding" is critical, and that a very simple routing algorithm will suffice provided there is path folding.
== Controversy ==


The disadvantage of this is that it is very easy for an attacker to find Freenet nodes, and connect to them, because every node is continually attempting to find new connections. In version 0.7, Freenet supports both "opennet" (similar to the old algorithms, but simpler), and "darknet" (all node connections are set up manually, so only your friends know your node's IP address). Darknet is less convenient, but much more secure against a distant attacker.
The same technology which allows the oppressed to communicate with a large group, without either the publisher or the readers' identities being revealed, can also allow controversial information such as drug related information or ] to be made available to anyone. Freenet's founders point out that only with true anonymity comes true freedom of speech, and that what they view as the beneficial uses of Freenet outweigh its negative uses. Due to the nature of Freenet a typical user may unknowingly host this sort of information, which may hypothetically make them subject to severe civil and criminal penalties. Freenet attempts to prevent this through "]", preventing the user himself from knowing what's on his own node and making it difficult to determine if a piece of information is in any given node without causing the distribution of that piece of information throughout the network to change in the process. No court cases have tested any of this to date.


This change required major changes in the routing algorithm. Every node has a location, which is a number between 0 and 1. When a key is requested, first the node checks the local data store. If it's not found, the key's hash is turned into another number in the same range, and the request is routed to the node whose location is closest to the key. This goes on until some number of hops is exceeded, there are no more nodes to search, or the data is found. If the data is found, it is cached on each node along the path. So there is no one source node for a key, and attempting to find where it is currently stored will result in it being cached more widely. Essentially the same process is used to insert a document into the network: the data is routed according to the key until it runs out of hops, and if no existing document is found with the same key, it is stored on each node. If older data is found, the older data is propagated and returned to the originator, and the insert "collides".
Some anonymous ] (F2F) networks do allow you to control what kind of files your friends exchange with your node in order to stop them from exchanging files you disapprove of but Freenet's "deniability" defence would not apply to users of these systems.


But this works only if the locations are clustered in the right way. Freenet assumes that the darknet (a subset of the global social network) is a small-world network, and nodes constantly attempt to swap locations (using the ]) in order to minimize their distance to their neighbors. If the network actually is a small-world network, Freenet should find data reasonably quickly; ideally on the order of <math>O\big(^2\big)</math> hops in ]. However, it does not guarantee that data will be found at all.<ref name=Clarke2010>{{cite book |last1=Clarke |first1=Ian |title=Private Communication Through a Network of Trusted Connections: The Dark Freenet |date=2010 |url=https://freenetproject.org/papers/freenet-0.7.5-paper.pdf |access-date=15 September 2015 |ref=Clarke2010 |archive-date=1 December 2017 |archive-url=https://web.archive.org/web/20171201033416/https://freenetproject.org/papers/freenet-0.7.5-paper.pdf |url-status=live}}</ref>
F2F prevents random people from proving that your IP address can effectively be used to get some controversial files. Freenet does not offer this protection because for efficiency reasons (path shortening) some random nodes are allowed to connect directly to your node, thus exchanging files faster, but thus knowing your IP and thus being able to prove that specific files can be obtained from your computer. However, due to Freenet's "plausible deniability" and the way in which Freenet redistributes files among nodes, one cannot prove that those files were placed there by the node owner or that the node owner knows what they are.


Eventually, either the document is found or the hop limit is exceeded. The terminal node sends a reply that makes its way back to the originator along the route specified by the intermediate nodes' records of pending requests. The intermediate nodes may choose to cache the document along the way. Besides saving bandwidth, this also makes documents harder to censor as there is no one "source node".
== Project related criticism ==


===Effect===
Some users have criticized the development process used by the Freenet project, which they claim has lead to poor human resource management, many delays, and poor development decisions. They claim this has resulted in a program that is hard to get working for regular users and behaves unpredictably. There is also many features they say are missing that should be in place after so many years of development. They also claim the Freenet project is not open enough to outside influences from other projects or non-developer participation.
]
Initially, the locations in darknet are distributed randomly. This means that routing of requests is essentially random. In opennet connections are established by a join request which provides an optimized network structure if the existing network is already optimized.<ref name=Roos2014>{{cite book|last1=Roos|first1=Stefanie|title=Measuring Freenet in the Wild: Censorship-Resilience under Observation|date=2014|publisher=Springer International Publishing|isbn=978-3-319-08505-0|pages=263–282|url=https://freenetproject.org/papers/roos-pets2014.pdf|access-date=15 September 2015|ref=Roos2014|archive-date=16 November 2014|archive-url=https://web.archive.org/web/20141116144052/https://freenetproject.org/papers/roos-pets2014.pdf|url-status=live}}</ref> So the data in a newly started Freenet will be distributed somewhat randomly.<ref>{{Cite web |title=Freenet Project Documentation |url=https://freenetproject.org/ |access-date=2022-04-20 |website=freenetproject.org |language=en |archive-date=16 February 2011 |archive-url=https://web.archive.org/web/20110216062257/http://freenetproject.org/ |url-status=live }}</ref>


As location swapping (on darknet) and path folding (on opennet) progress, nodes which are close to one another will increasingly have close locations, and nodes which are far away will have distant locations. Data with similar keys will be stored on the same node.<ref name=Roos2014 />
== Related tools ==
=== Freesite Insertion Wizard (FIW) ===
FIW is one of the most popular of all the Freenet tools. It is currently the best maintained insertion tool for ]s. It is written in ] and provides both a terminal interface and a ]. It supports the latest Freenet technologies such as containers as well.


The result is that the network will self-organize into a distributed, clustered structure where nodes tend to hold data items that are close together in key space. There will probably be multiple such clusters throughout the network, any given document being replicated numerous times, depending on how much it is used. This is a kind of "]", in which an initially symmetric state (all nodes being the same, with random initial keys for each other) leads to a highly asymmetric situation, with nodes coming to specialize in data that has closely related keys.{{citation needed|date=July 2013}}
=== Fishtools ===


There are forces which tend to cause clustering (shared closeness data spreads throughout the network), and forces that tend to break up clusters (local caching of commonly used data). These forces will be different depending on how often data is used, so that seldom-used data will tend to be on just a few nodes which specialize in providing that data, and frequently used items will be spread widely throughout the network. This automatic mirroring counteracts the times when ] becomes overloaded, and due to a mature network's intelligent routing, a network of size ''n'' should require only log(''n'') time to retrieve a document on average.<ref>{{cite web|url=https://www.networxsecurity.org/members-area/glossary/f/freenet.html|title=FreeNet|website=networxsecurity.org|access-date=25 January 2019|archive-date=26 January 2019|archive-url=https://web.archive.org/web/20190126001007/https://www.networxsecurity.org/members-area/glossary/f/freenet.html|url-status=live}}</ref>
Another extremely popular tool for inserting freesites. However, due to an argument, its main developer has broken off with the Freenet community, and it is no longer maintained. It is written in ] and it is still widely used and fairly up to date.


===Keys===
=== Freenet Utility for Queued Inserts and Downloads (FUQID) ===
Keys are ]: there is no notion of ] when speaking of key closeness. Therefore, there will be no correlation between key closeness and similar popularity of data as there might be if keys did exhibit some semantic meaning, thus avoiding bottlenecks caused by popular subjects.


There are two main varieties of keys in use on Freenet, the Content Hash Key (CHK) and the Signed Subspace Key (SSK). A subtype of SSKs is the Updatable Subspace Key (USK) which adds versioning to allow secure updating of content.
This is a ]-only tool (although reports say it works under too), typically used to retrieve large splitfiles and to insert non-Freesite content such as binaries, audio, and archives. It is written in ], and it is maintained sporadically. It is generally regarded as an excellent complement to either FIW or Fishtools.


A CHK is a ] hash of a document (after encryption, which itself depends on the hash of the plaintext) and thus a node can check that the document returned is correct by hashing it and checking the digest against the key. This key contains the meat of the data on Freenet. It carries all the binary data building blocks for the content to be delivered to the client for reassembly and decryption. The CHK is unique by nature and provides tamperproof content. A hostile node altering the data under a CHK will immediately be detected by the next node or the client. CHKs also reduce the redundancy of data since the same data will have the same CHK and when multiple sites reference the same large files, they can reference to the same CHK.<ref>{{cite web|title=freesitemgr, code for inserting files as CHK, fixed revision|website=]|url=https://github.com/freenet/lib-pyFreenet/blob/b78aea05222c4afe5145d8b529d2a54d4b93887a/fcp/sitemgr.py#L976|access-date=29 November 2017|archive-date=5 February 2022|archive-url=https://web.archive.org/web/20220205041918/https://github.com/freenet/pyFreenet/blob/b78aea05222c4afe5145d8b529d2a54d4b93887a/fcp/sitemgr.py#L976|url-status=live}}</ref>
=== FCPTools ===


SSKs are based on public-key cryptography. Currently Freenet uses the ] algorithm. Documents inserted under SSKs are signed by the inserter, and this signature can be verified by every node to ensure that the data is not tampered with. SSKs can be used to establish a verifiable ] identity on Freenet, and allow for multiple documents to be inserted securely by a single person. Files inserted with an SSK are effectively ], since inserting a second file with the same name can cause collisions. USKs resolve this by adding a version number to the keys which is also used for providing update notification for keys registered as bookmarks in the web interface.<ref>{{cite web|last1=Babenhauserheide|first1=Arne|title=USK and Date-Hints: Finding the newest version of a site in Freenet's immutable datastore|url=http://draketo.de/light/english/freenet/usk-and-date-hints|website=draketo.de|access-date=29 November 2017|archive-date=8 February 2015|archive-url=https://web.archive.org/web/20150208101405/http://draketo.de/light/english/freenet/usk-and-date-hints|url-status=live}}</ref> Another subtype of the SSK is the Keyword Signed Key, or KSK, in which the key pair is generated in a standard way from a simple human-readable string. Inserting a document using a KSK allows the document to be retrieved and decrypted if and only if the requester knows the human-readable string; this allows for more convenient (but less secure) ] for users to refer to.<ref>{{cite web|last1=Babenhauserheide|first1=Arne|title=Effortless password protected sharing of files via Freenet|url=http://draketo.de/light/english/freenet/effortless-password-protected-sharing-files|website=draketo.de|access-date=29 November 2017|archive-date=10 September 2015|archive-url=https://web.archive.org/web/20150910030851/http://draketo.de/light/english/freenet/effortless-password-protected-sharing-files|url-status=live}}</ref>
The are command-line driven programs for inserting and retrieving files with Freenet. Included separately is FCPLib, the Freenet Client Protocol Library. The FCPTools are linked against FCPLib and serve as nice examples for using the library in Freenet client programs.


==Scalability==
(Freenet Client Protocol Library) aims to be a ] but natively ] set of ]-based functions for storing and retrieving information to and from Freenet. There are routines for storing documents to Freenet from the local disk, and other routines for moving data in memory to and from Freenet.
A ] is said to be scalable if its performance does not deteriorate even if the network is very large. The scalability of Freenet is being evaluated, but similar architectures have been shown to scale logarithmically.<ref>{{cite book |doi=10.1145/335305.335325 |chapter=The Small-World Phenomenon: An Algorithmic Perspective |title=Proceedings of the thirty-second annual ACM symposium on Theory of computing |year=2000 |last1=Kleinberg |first1=Jon |isbn=978-1-58113-184-0 |pages=163–70 |s2cid=221559836 |chapter-url=http://www.cs.cornell.edu/home/kleinber/swn.pdf |access-date=22 August 2013 |archive-date=12 November 2013 |archive-url=https://web.archive.org/web/20131112052807/http://www.cs.cornell.edu/home/kleinber/swn.pdf |url-status=live }}</ref> This work indicates that Freenet can find data in <math>O(\log^2 n)</math> hops on a small-world network (which includes both opennet and darknet style Freenet networks), when ignoring the caching which could improve the scalability for popular content. However, this scalability is difficult to test without a very large network. Furthermore, the security features inherent to Freenet make detailed performance analysis (including things as simple as determining the size of the network) difficult to do accurately. As of now, the scalability of Freenet has yet to be tested.


==Darknet versus opennet==
Everything is released under the ] ].
As of version 0.7, Freenet supports both "darknet" and "opennet" connections. Opennet connections are made automatically by nodes with opennet enabled, while darknet connections are manually established between users that know and trust each other. Freenet developers describe the trust needed as "will not crack their Freenet node".<ref>{{cite web |url=https://d6.gnutella2.info/freenet/USK@sUm3oJISSEU4pl2Is9qa1eRoCLyz6r2LPkEqlXc3~oc,yBEbf-IJrcB8Pe~gAd53DEEHgbugUkFSHtzzLqnYlbs,AQACAAE/random_babcom/156/#Requiredtrustforformingadarknetconnection |title=Required trust for forming a darknet connection |website=random_babcom |access-date=29 November 2017 |archive-date=7 October 2015 |url-status=dead |archive-url=https://web.archive.org/web/20151007012112/https://d6.gnutella2.info/freenet/USK@sUm3oJISSEU4pl2Is9qa1eRoCLyz6r2LPkEqlXc3~oc,yBEbf-IJrcB8Pe~gAd53DEEHgbugUkFSHtzzLqnYlbs,AQACAAE/random_babcom/156/#Requiredtrustforformingadarknetconnection }}</ref> Opennet connections are easy to use, but darknet connections are more secure against attackers on the network, and can make it difficult for an attacker (such as an oppressive government) to even determine that a user is running Freenet in the first place.<ref>{{cite news|url=http://www.golem.de/0805/59592.html|title=Darknet-Fähigkeiten sollen Softwarenutzung verbergen|date=9 May 2008|access-date=29 November 2017|publisher=Golem|archive-date=5 October 2015|archive-url=https://web.archive.org/web/20151005070232/http://www.golem.de/0805/59592.html|url-status=live}}</ref>


The core innovation in Freenet 0.7 is to allow a globally scalable darknet, capable (at least in theory) of supporting millions of users. Previous darknets, such as ], have been limited to relatively small disconnected networks. The scalability of Freenet is made possible by the fact that human relationships tend to form small-world networks, a property that can be exploited to find short paths between any two people. The work is based on a speech given at ] by ] and Swedish mathematician ]. Furthermore, the routing algorithm is capable of routing over a mixture of opennet and darknet connections, allowing people who have only a few friends using the network to get the performance from having sufficient connections while still receiving some of the security benefits of darknet connections. This also means that small darknets where some users also have opennet connections are fully integrated into the whole Freenet network, allowing all users access to all content, whether they run opennet, darknet, or a hybrid of the two, except for darknet pockets connected only by a single hybrid node.<ref name=Roos2014 />
FCPLib is now routinely compiled on the following platforms: ] (NT/2K/XP), ] ], ], ], and ].


=== Freenet Tools === == Tools and applications ==
]]]
The Freenet Tools perform roughly the same tasks as FCPTools, however it does not include a client library for use in other projects. It is written in ], and runs under ].


Unlike many other P2P applications Freenet does not provide comprehensive functionality itself. Freenet is modular and features an ] called Freenet Client Protocol (FCP) for other programs to use to implement services such as ], file sharing, or ].<ref> {{Webarchive|url=https://web.archive.org/web/20150815123435/http://freesocial.draketo.de/ |date=15 August 2015 }} Justus Ranvier, 2013</ref>
=== Frost ===
is a well-maintained and popular message board system for Freenet. It uses a ] concept as well as public and private keys to prevent excess ]. It is very popular in the area of ] and is the most widely used Freenet messaging application. For a long time many people preferred Freenet Message Board (FMB) but it has fallen into disuse. It is written in ] and therefore works on any platform where a ] is available, such as ], ], ] and other ]s.


===Communication===
=== Freenet Message Board (FMB) ===
'''Freenet Messaging System (FMS)'''
:FMS was designed to address problems with Frost such as ] attacks and spam. Users publish trust lists, and each user downloads messages only from identities they trust and identities trusted by identities they trust. FMS is developed anonymously and can be downloaded from ''the FMS freesite'' within Freenet. It does not have an official site on the normal Internet. It features random post delay, support for many identities, and a distinction between trusting a user's posts and trusting their trust list. It is written in C++ and is a separate application from Freenet which uses the Freenet Client Protocol (FCP) to interface with Freenet.
'''Frost'''
:Frost includes support for convenient file sharing, but its design is inherently vulnerable to spam and ] attacks.<ref> {{Webarchive|url=https://web.archive.org/web/20171201033622/https://www.mail-archive.com/devl@freenetproject.org/msg17363.html |date=1 December 2017 }} Matthew Toseland, 2007</ref> Frost can be downloaded from the Frost home page on SourceForge, or from ''the Frost freesite'' within Freenet. It is not endorsed by the Freenet developers. Frost is written in Java and is a separate application from Freenet.
'''Sone'''
:Sone provides a simpler interface inspired by Facebook<ref> {{Webarchive|url=https://web.archive.org/web/20171201042007/https://flattr.com/thing/81996/Sone-The-Freenet-Social-Network-Plugin |date=1 December 2017 }}, "it's a Facebook clone on top of Freenet", retrieved 15 September 2015</ref> with public anonymous discussions and image galleries. It provides an API for control from other programs<ref> {{Webarchive|url=https://web.archive.org/web/20150812111038/https://wiki.freenetproject.org/Sone |date=12 August 2015 }}, with the description of the FCP API, retrieved 14 September 2015</ref> is also used to implement a comment system for static websites in the regular internet.<ref> {{Webarchive|url=https://web.archive.org/web/20150511180725/http://draketo.de/proj/freecom/ |date=11 May 2015 }}, "it submits a search request on your local Sone instance by creating an iframe with the right URL", 2014.</ref><ref>{{cite web | url=https://d6.gnutella2.info/freenet/USK@nwa8lHa271k2QvJ8aa0Ov7IHAV-DFOCFgmDt3X6BpCI,DuQSUZiI~agF8c-6tjsFFGuZ8eICrzWCILB60nT8KKo,AQACAAE/sone/71/ | title=Sone | access-date=15 September 2015 | archive-date=2 October 2015 | archive-url=https://web.archive.org/web/20151002144720/https://d6.gnutella2.info/freenet/USK@nwa8lHa271k2QvJ8aa0Ov7IHAV-DFOCFgmDt3X6BpCI,DuQSUZiI~agF8c-6tjsFFGuZ8eICrzWCILB60nT8KKo,AQACAAE/sone/71/ | url-status=live }}</ref>


===Utilities===
The Freenet Message Board is the most branched message board software for Freenet ever coded. It is written in ], and the original author does not maintain it. However, the community continues to provide several branches which are generally up to date. It works on both ] and ].
'''jSite'''
:jSite is a tool to upload websites. It handles keys and manages uploading files.
'''Infocalypse'''
:Infocalypse is an extension for the distributed revision control system ]. It uses an optimized structure to minimize the number of requests to retrieve new data, and allows supporting a repository by securely reuploading most parts of the data without requiring the owner's private keys.<ref name="infocalypse-info">{{cite web | url=http://draketo.de/light/english/freenet/infocalypse-mercurial-survive-the-information-apocalypse#advocacy | title=Information about infocalypse. A mirror of the included documentation | access-date=16 December 2011 | archive-date=27 January 2012 | archive-url=https://web.archive.org/web/20120127055008/http://draketo.de/light/english/freenet/infocalypse-mercurial-survive-the-information-apocalypse#advocacy | url-status=live }}</ref>

===Libraries===
'''FCPLib'''
:FCPLib (Freenet Client Protocol Library) aims to be a ] natively ] set of ]-based functions for storing and retrieving information to and from Freenet. FCPLib supports Windows NT/2K/XP, ], ], ], and ].
'''lib-pyFreenet'''
:lib-pyFreenet exposes Freenet functionality to ] programs. Infocalypse uses it.

==Vulnerabilities==
Law enforcement agencies have claimed to have successfully infiltrated Freenet opennet in order to deanonymize users<ref>{{cite news |last=Volpenheim |first=Sarah |url=https://www.thedickinsonpress.com/news/predators-police-in-online-struggle |title=Predators, police in online struggle |newspaper=The Dickinson Press |date=18 November 2015 |access-date=30 December 2023 |archive-date=30 December 2023 |archive-url=https://web.archive.org/web/20231230234948/https://www.thedickinsonpress.com/news/predators-police-in-online-struggle |url-status=live }}</ref> but no technical details have been given to support these allegations. One report stated that, "A ] investigation focused on&nbsp;... when the authorities were monitoring the online network, Freenet."<ref>{{Cite news|url=https://arstechnica.com/tech-policy/2017/03/man-jailed-indefinitely-for-refusing-to-decrypt-hard-drives-loses-appeal/|title=Man jailed indefinitely for refusing to decrypt hard drives loses appeal|date=20 March 2017|work=Ars Technica|access-date=21 March 2017|language=en-us|archive-date=21 March 2017|archive-url=https://web.archive.org/web/20170321062227/https://arstechnica.com/tech-policy/2017/03/man-jailed-indefinitely-for-refusing-to-decrypt-hard-drives-loses-appeal/|url-status=live}}</ref> A different report indicated arrests may have been based on the BlackICE project leaks, that are debunked for using bad math<ref>{{cite web|url=https://freenetproject.org/police-departments-tracking-efforts-based-on-false-statistics.html|title=Police department's tracking efforts based on false statistics|website=freenetproject.org|date=26 May 2016 |access-date=23 September 2017|archive-date=5 February 2022|archive-url=https://web.archive.org/web/20220205041920/https://freenetproject.org/police-departments-tracking-efforts-based-on-false-statistics.html|url-status=live}}</ref> and for using an incorrectly calculated false positives rate and a false model.<ref>{{cite web|url=https://www.draketo.de/software/levine-2017-errors|website=draketo.de|access-date=3 January 2021|title=Errors in the Levine 2017 paper on attacks against Freenet|archive-date=14 April 2021|archive-url=https://web.archive.org/web/20210414044800/https://www.draketo.de/software/levine-2017-errors|url-status=live}}</ref>

A court case in the Peel Region of Ontario, ''Canada R. v. Owen'', 2017 ONCJ 729 (CanLII), illustrated that law enforcement do in fact have a presence, after Peel Regional Police located who had been downloading illegal material on the Freenet network.<ref>{{cite web|url=https://www.canlii.org/en/on/oncj/doc/2017/2017oncj729/2017oncj729.html|title=CanLII - 2017 ONCJ 729 (CanLII)|access-date=13 November 2017|archive-date=17 January 2021|archive-url=https://web.archive.org/web/20210117201444/https://www.canlii.org/en/on/oncj/doc/2017/2017oncj729/2017oncj729.html|url-status=live}}</ref> The court decision indicates that a Canadian Law Enforcement agency operates nodes running modified Freenet software in the hope of determining who is requesting illegal material.

*'''Routing Table Insertion''' (RTI) Attack<ref>{{cite web| url = https://www.researchgate.net/publication/261061477| title = A Routing Table Insertion (RTI) Attack on Freenet| access-date = 12 February 2021| archive-date = 5 February 2022| archive-url = https://web.archive.org/web/20220205041920/https://www.researchgate.net/publication/261061477_A_Routing_Table_Insertion_RTI_Attack_on_Freenet| url-status = live}}</ref>

==Notability==
Freenet has had significant publicity in the mainstream press, including articles in '']'', and coverage on ], '']'', the ], '']'',<ref name="The Guardian-Beckett2009" /> and elsewhere.

Freenet received the SUMA-Award 2014 for "protection against total surveillance".<ref name=suma_award /><ref name=suma_award_recording /><ref name=suma_award_heise />

==Freesite==
A "freesite" is a site hosted on the Freenet network. Because it contains only static content, it cannot contain any active content like server-side scripts or databases. Freesites are coded in HTML and support as many features as the browser viewing the page allows; however, there are some exceptions where the Freenet software will remove parts of the code that may be used to reveal the identity of the person viewing the page (making a page access something on the internet, for example).


==See also== ==See also==
{{Portal|Free and open-source software}}
* ]
* ]
* ] * ]
* ] * ]
* ] * ]
* ] * ]
* ] * ]
* ] networks * ]

===Comparable software===
* ] * ]
* ] * ]
* ]
* ]
* ] (also known as JonDonym)
* ]
* ] – also creates a distributed data store shared by anonymous nodes; the successor to ], which itself is the successor of ]
* ]
* ]

==References==
{{Reflist|25em}}

==Further reading==
*{{cite journal |doi=10.1109/4236.978368 |title=Protecting free expression online with Freenet |year=2002 |last1=Clarke |first1=I. |last2=Miller |first2=S.G. |last3=Hong |first3=T.W. |last4=Sandberg |first4=O. |last5=Wiley |first5=B. |journal=IEEE Internet Computing |volume=6 |issue=1 |pages=40–9|url=http://www.doc.ic.ac.uk/~twh1/longitude/papers/ieee-final.pdf |archive-url=https://web.archive.org/web/20040720044931/http://www.doc.ic.ac.uk/~twh1/longitude/papers/ieee-final.pdf |archive-date=2004-07-20 |url-status=live |citeseerx=10.1.1.21.9143 }}
*{{cite journal |doi=10.1016/S0048-7333(03)00050-7 |title=Community, joining, and specialization in open source software innovation: A case study |year=2003 |last1=Von Krogh |first1=Georg |last2=Spaeth |first2=Sebastian |last3=Lakhani |first3=Karim R |journal=Research Policy |volume=32 |issue=7 |pages=1217–41|url=https://www.alexandria.unisg.ch/30623/1/Community%2C%20joining%2C%20and%20specialization%20in%20open%20source%20software%20innovation%20-%20a%20case%20study.pdf |archive-url=https://web.archive.org/web/20180720115900/https://www.alexandria.unisg.ch/30623/1/Community%2C%20joining%2C%20and%20specialization%20in%20open%20source%20software%20innovation%20-%20a%20case%20study.pdf |archive-date=2018-07-20 |url-status=live }}
*{{cite book |doi=10.1007/3-540-44702-4_5 |chapter=The Free Haven Project: Distributed Anonymous Storage Service |title=Designing Privacy Enhancing Technologies |series=Lecture Notes in Computer Science |year=2001 |last1=Dingledine |first1=Roger |last2=Freedman |first2=Michael J. |last3=Molnar |first3=David |isbn=978-3-540-41724-8 |pages=67–95|citeseerx=10.1.1.420.478 }}
*{{cite book |doi=10.1007/3-540-44702-4_4 |chapter=Freenet: A Distributed Anonymous Information Storage and Retrieval System |title=Designing Privacy Enhancing Technologies |series=Lecture Notes in Computer Science |year=2001 |last1=Clarke |first1=Ian |last2=Sandberg |first2=Oskar |last3=Wiley |first3=Brandon |last4=Hong |first4=Theodore W. |isbn=978-3-540-41724-8 |pages=46–66|citeseerx=10.1.1.26.4923 }}
*{{cite journal |first1=Damien A. |last1=Riehl |year=2000 |title=Peer-to-Peer Distribution Systems: Will Napster, Gnutella, and Freenet Create a Copyright Nirvana or Gehenna? |journal=The William Mitchell Law Review |volume=27 |issue=3 |page=1761}}
*{{cite journal |first1=Ryan |last1=Roemer |date=Fall 2002 |title=The Digital Evolution: Freenet and the Future of Copyright on the Internet |journal=UCLA Journal of Law and Technology |volume=5 |url=http://www.lawtechjournal.com/articles/2002/05_021229_roemer.php}}
*{{cite journal |last1=Sun |first1=Xiaoqing |last2=Liu |first2=Baoxu |last3=Feng |first3=Dengguo |year=2005 |title=Analysis of Next Generation Routing of Freenet |journal=Computer Engineering |issue=17 |pages=126–8}}
*{{cite book |doi=10.1109/INFCOM.2002.1019373 |chapter=Using the small-world model to improve Freenet performance |title=INFOCOM 2002: Twenty-First Annual Joint Conference of the IEEE Computer and Communications Societies |year=2002 |last1=Hui Zhang |last2=Goel |first2=Ashish |last3=Govindan |first3=Ramesh |isbn=978-0-7803-7476-8 |volume=3 |pages=1228–37|citeseerx=10.1.1.74.7011 |s2cid=13182323 }}


==External links== ==External links==
*{{official}}
*
*
* - Site in Chinese
* - Wiki devoted to Freenet, suitable for technical discussions and content]
* {{note|2}} - An analysis of the types of files contained in Freenet
* - An online debate between Ian Clarke, Freenet's creator, and Matt Oppenheim, the ]'s senior vice president of business and legal affairs
*


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Latest revision as of 19:17, 12 December 2024

Peer-to-peer Internet platform for censorship-resistant communication For other uses, see Freenet (disambiguation).

Logo of Freenet
Screenshot of Freenet 0.7.5FProxy index page (Freenet 0.7)
Developer(s)
Initial releaseMarch 2000; 24 years ago (2000-03)
Stable release0.7.5 build 1498 Edit this on Wikidata / 23 September 2024
Repositoryhttps://github.com/hyphanet/fred
Written inJava
Operating systemCross-platform: Unix-like (Android, Linux, BSD, macOS), Microsoft Windows
PlatformJava
Available inEnglish, French, Italian, German, Dutch, Spanish, Portuguese, Swedish, Norwegian, Chinese, Russian
TypeAnonymity application, peer-to-peer, friend-to-friend, overlay network, mix network, distributed data store
LicenseGNU General Public License version 3 only
Websitewww.hyphanet.org
Part of a series on
File sharing
Technologies
Video on demand sites
BitTorrent sites
Academic/scholarly
File sharing networks
P2P clients
Streaming programs
Anonymous file sharing
Development and societal aspects
By country or region
Comparisons

Hyphanet (until mid-2023: Freenet) is a peer-to-peer platform for censorship-resistant, anonymous communication. It uses a decentralized distributed data store to keep and deliver information, and has a suite of free software for publishing and communicating on the Web without fear of censorship. Both Freenet and some of its associated tools were originally designed by Ian Clarke, who defined Freenet's goal as providing freedom of speech on the Internet with strong anonymity protection.

The distributed data store of Freenet is used by many third-party programs and plugins to provide microblogging and media sharing, anonymous and decentralised version tracking, blogging, a generic web of trust for decentralized spam resistance, Shoeshop for using Freenet over sneakernet, and many more.

History

The origin of Freenet can be traced to Ian Clarke's student project at the University of Edinburgh, which he completed as a graduation requirement in the summer of 1999. Ian Clarke's resulting unpublished report "A distributed decentralized information storage and retrieval system" (1999) provided foundation for the seminal paper written in collaboration with other researchers, "Freenet: A Distributed Anonymous Information Storage and Retrieval System" (2001). According to CiteSeer, it became one of the most frequently cited computer science articles in 2002.

Freenet can provide anonymity on the Internet by storing small encrypted snippets of content distributed on the computers of its users and connecting only through intermediate computers which pass on requests for content and sending them back without knowing the contents of the full file. This is similar to how routers on the Internet route packets without knowing anything about files‍— except Freenet has caching, a layer of strong encryption, and no reliance on centralized structures. This allows users to publish anonymously or retrieve various kinds of information.

Release history

The Freenet 0.7 darknet peers list.

Freenet has been under continuous development since 2000.

Freenet 0.7, released on 8 May 2008, is a major re-write incorporating a number of fundamental changes. The most fundamental change is support for darknet operation. Version 0.7 offered two modes of operation: a mode in which it connects only to friends, and an opennet-mode in which it connects to any other Freenet user. Both modes can be run simultaneously. When a user switches to pure darknet operation, Freenet becomes very difficult to detect from the outside. The transport layer created for the darknet mode allows communication over restricted routes as commonly found in mesh networks, as long as these connections follow a small-world structure. Other modifications include switching from TCP to UDP, which allows UDP hole punching along with faster transmission of messages between peers in the network.

Freenet 0.7.5, released on 12 June 2009, offers a variety of improvements over 0.7. These include reduced memory usage, faster insert and retrieval of content, significant improvements to the FProxy web interface used for browsing freesites, and a large number of smaller bugfixes, performance enhancements, and usability improvements. Version 0.7.5 also shipped with a new version of the Windows installer.

As of build 1226, released on 30 July 2009, features that have been written include significant security improvements against both attackers acting on the network and physical seizure of the computer running the node.

As of build 1468, released on 11 July 2015, the Freenet core stopped using the db4o database and laid the foundation for an efficient interface to the Web of Trust plugin which provides spam resistance.

Freenet has always been free software, but until 2011 it required users to install Java. This problem was solved by making Freenet compatible with OpenJDK, a free and open source implementation of the Java Platform.

On 11 February 2015, Freenet received the SUMA-Award for "protection against total surveillance".

Features and user interface

Freenet served as the model for the Japanese peer to peer file-sharing programs Winny, Share and Perfect Dark, but this model differs from p2p networks such as Bittorrent and emule. Freenet separates the underlying network structure and protocol from how users interact with the network; as a result, there are a variety of ways to access content on the Freenet network. The simplest is via FProxy, which is integrated with the node software and provides a web interface to content on the network. Using FProxy, a user can browse freesites (websites that use normal HTML and related tools, but whose content is stored within Freenet rather than on a traditional web server). The web interface is also used for most configuration and node management tasks. Through the use of separate applications or plugins loaded into the node software, users can interact with the network in other ways, such as forums similar to web forums or Usenet or interfaces more similar to traditional P2P "filesharing" interfaces.

While Freenet provides an HTTP interface for browsing freesites, it is not a proxy for the World Wide Web; Freenet can be used to access only the content that has been previously inserted into the Freenet network. In this way, it is more similar to Tor's onion services than to anonymous proxy software like Tor's proxy.

Freenet's focus lies on free speech and anonymity. Because of that, Freenet acts differently at certain points that are (directly or indirectly) related to the anonymity part. Freenet attempts to protect the anonymity of both people inserting data into the network (uploading) and those retrieving data from the network (downloading). Unlike file sharing systems, there is no need for the uploader to remain on the network after uploading a file or group of files. Instead, during the upload process, the files are broken into chunks and stored on a variety of other computers on the network. When downloading, those chunks are found and reassembled. Every node on the Freenet network contributes storage space to hold files and bandwidth that it uses to route requests from its peers.

As a direct result of the anonymity requirements, the node requesting content does not normally connect directly to the node that has it; instead, the request is routed across several intermediaries, none of which know which node made the request or which one had it. As a result, the total bandwidth required by the network to transfer a file is higher than in other systems, which can result in slower transfers, especially for infrequently accessed content.

Since version 0.7, Freenet offers two different levels of security: opennet and darknet. With opennet, users connect to arbitrary other users. With darknet, users connect only to "friends" with whom they previously exchanged public keys, named node-references. Both modes can be used together.

Content

Freenet's founders argue that true freedom of speech comes only with true anonymity and that the beneficial uses of Freenet outweigh its negative uses. Their view is that free speech, in itself, is not in contradiction with any other consideration—the information is not the crime. Freenet attempts to remove the possibility of any group imposing its beliefs or values on any data. Although many states censor communications to different extents, they all share one commonality in that a body must decide what information to censor and what information to allow. What may be acceptable to one group of people may be considered offensive or even dangerous to another. In essence, the purpose of Freenet is to ensure that no one is allowed to decide what is acceptable.

Reports of Freenet's use in authoritarian nations is difficult to track due to the very nature of Freenet's goals. One group, Freenet China, used to introduce the Freenet software to Chinese users starting from 2001 and distribute it within China through e-mails and on disks after the group's website was blocked by the Chinese authorities on the mainland. It was reported that in 2002 Freenet China had several thousand dedicated users. However, Freenet opennet traffic was blocked in China around the 2010s.

Technical design

See also: Cryptography

The Freenet file sharing network stores documents and allows them to be retrieved later by an associated key, as is now possible with protocols such as HTTP. The network is designed to be highly survivable. The system has no central servers and is not subject to the control of any one individual or organization, including the designers of Freenet. The codebase size is over 192,000 lines of code. Information stored on Freenet is distributed around the network and stored on several different nodes. Encryption of data and relaying of requests makes it difficult to determine who inserted content into Freenet, who requested that content, or where the content was stored. This protects the anonymity of participants, and also makes it very difficult to censor specific content. Content is stored encrypted, making it difficult for even the operator of a node to determine what is stored on that node. This provides plausible deniability; which, in combination with request relaying, means that safe harbor laws that protect service providers may also protect Freenet node operators. When asked about the topic, Freenet developers defer to the EFF discussion which says that not being able to filter anything is a safe choice.

Distributed storage and caching of data

Like Winny, Share and Perfect Dark, Freenet not only transmits data between nodes but actually stores them, working as a huge distributed cache. To achieve this, each node allocates some amount of disk space to store data; this is configurable by the node operator, but is typically several GB (or more).

Files on Freenet are typically split into multiple small blocks, with duplicate blocks created to provide redundancy. Each block is handled independently, meaning that a single file may have parts stored on many different nodes.

Information flow in Freenet is different from networks like eMule or BitTorrent; in Freenet:

  1. A user wishing to share a file or update a freesite "inserts" the file "to the network"
  2. After "insertion" is finished, the publishing node is free to shut down, because the file is stored in the network. It will remain available for other users whether or not the original publishing node is online. No single node is responsible for the content; instead, it is replicated to many different nodes.

Two advantages of this design are high reliability and anonymity. Information remains available even if the publisher node goes offline, and is anonymously spread over many hosting nodes as encrypted blocks, not entire files.

The key disadvantage of the storage method is that no one node is responsible for any chunk of data. If a piece of data is not retrieved for some time and a node keeps getting new data, it will drop the old data sometime when its allocated disk space is fully used. In this way Freenet tends to 'forget' data which is not retrieved regularly (see also Effect).

While users can insert data into the network, there is no way to delete data. Due to Freenet's anonymous nature the original publishing node or owner of any piece of data is unknown. The only way data can be removed is if users don't request it.

Network

Typically, a host computer on the network runs the software that acts as a node, and it connects to other hosts running that same software to form a large distributed, variable-size network of peer nodes. Some nodes are end user nodes, from which documents are requested and presented to human users. Other nodes serve only to route data. All nodes communicate with each other identically – there are no dedicated "clients" or "servers". It is not possible for a node to rate another node except by its capacity to insert and fetch data associated with a key. This is unlike most other P2P networks where node administrators can employ a ratio system, where users have to share a certain amount of content before they can download.

Freenet may also be considered a small world network.

The Freenet protocol is intended to be used on a network of complex topology, such as the Internet (Internet Protocol). Each node knows only about some number of other nodes that it can reach directly (its conceptual "neighbors"), but any node can be a neighbor to any other; no hierarchy or other structure is intended. Each message is routed through the network by passing from neighbor to neighbor until it reaches its destination. As each node passes a message to a neighbor, it does not know whether the neighbor will forward the message to another node, or is the final destination or original source of the message. This is intended to protect the anonymity of users and publishers.

Each node maintains a data store containing documents associated with keys, and a routing table associating nodes with records of their performance in retrieving different keys.

Protocol

A typical request sequence. The request moves through the network from node to node, backing out of a dead-end (step 3) and a loop (step 7) before locating the desired file.

The Freenet protocol uses a key-based routing protocol, similar to distributed hash tables. The routing algorithm changed significantly in version 0.7. Prior to version 0.7, Freenet used a heuristic routing algorithm where each node had no fixed location, and routing was based on which node had served a key closest to the key being fetched (in version 0.3) or which is estimated to serve it faster (in version 0.5). In either case, new connections were sometimes added to downstream nodes (i.e. the node that answered the request) when requests succeeded, and old nodes were discarded in least recently used order (or something close to it). Oskar Sandberg's research (during the development of version 0.7) shows that this "path folding" is critical, and that a very simple routing algorithm will suffice provided there is path folding.

The disadvantage of this is that it is very easy for an attacker to find Freenet nodes, and connect to them, because every node is continually attempting to find new connections. In version 0.7, Freenet supports both "opennet" (similar to the old algorithms, but simpler), and "darknet" (all node connections are set up manually, so only your friends know your node's IP address). Darknet is less convenient, but much more secure against a distant attacker.

This change required major changes in the routing algorithm. Every node has a location, which is a number between 0 and 1. When a key is requested, first the node checks the local data store. If it's not found, the key's hash is turned into another number in the same range, and the request is routed to the node whose location is closest to the key. This goes on until some number of hops is exceeded, there are no more nodes to search, or the data is found. If the data is found, it is cached on each node along the path. So there is no one source node for a key, and attempting to find where it is currently stored will result in it being cached more widely. Essentially the same process is used to insert a document into the network: the data is routed according to the key until it runs out of hops, and if no existing document is found with the same key, it is stored on each node. If older data is found, the older data is propagated and returned to the originator, and the insert "collides".

But this works only if the locations are clustered in the right way. Freenet assumes that the darknet (a subset of the global social network) is a small-world network, and nodes constantly attempt to swap locations (using the Metropolis–Hastings algorithm) in order to minimize their distance to their neighbors. If the network actually is a small-world network, Freenet should find data reasonably quickly; ideally on the order of O ( [ log ( n ) ] 2 ) {\displaystyle O{\big (}^{2}{\big )}} hops in big O notation. However, it does not guarantee that data will be found at all.

Eventually, either the document is found or the hop limit is exceeded. The terminal node sends a reply that makes its way back to the originator along the route specified by the intermediate nodes' records of pending requests. The intermediate nodes may choose to cache the document along the way. Besides saving bandwidth, this also makes documents harder to censor as there is no one "source node".

Effect

The effect of the node specialising on the particular location.

Initially, the locations in darknet are distributed randomly. This means that routing of requests is essentially random. In opennet connections are established by a join request which provides an optimized network structure if the existing network is already optimized. So the data in a newly started Freenet will be distributed somewhat randomly.

As location swapping (on darknet) and path folding (on opennet) progress, nodes which are close to one another will increasingly have close locations, and nodes which are far away will have distant locations. Data with similar keys will be stored on the same node.

The result is that the network will self-organize into a distributed, clustered structure where nodes tend to hold data items that are close together in key space. There will probably be multiple such clusters throughout the network, any given document being replicated numerous times, depending on how much it is used. This is a kind of "spontaneous symmetry breaking", in which an initially symmetric state (all nodes being the same, with random initial keys for each other) leads to a highly asymmetric situation, with nodes coming to specialize in data that has closely related keys.

There are forces which tend to cause clustering (shared closeness data spreads throughout the network), and forces that tend to break up clusters (local caching of commonly used data). These forces will be different depending on how often data is used, so that seldom-used data will tend to be on just a few nodes which specialize in providing that data, and frequently used items will be spread widely throughout the network. This automatic mirroring counteracts the times when web traffic becomes overloaded, and due to a mature network's intelligent routing, a network of size n should require only log(n) time to retrieve a document on average.

Keys

Keys are hashes: there is no notion of semantic closeness when speaking of key closeness. Therefore, there will be no correlation between key closeness and similar popularity of data as there might be if keys did exhibit some semantic meaning, thus avoiding bottlenecks caused by popular subjects.

There are two main varieties of keys in use on Freenet, the Content Hash Key (CHK) and the Signed Subspace Key (SSK). A subtype of SSKs is the Updatable Subspace Key (USK) which adds versioning to allow secure updating of content.

A CHK is a SHA-256 hash of a document (after encryption, which itself depends on the hash of the plaintext) and thus a node can check that the document returned is correct by hashing it and checking the digest against the key. This key contains the meat of the data on Freenet. It carries all the binary data building blocks for the content to be delivered to the client for reassembly and decryption. The CHK is unique by nature and provides tamperproof content. A hostile node altering the data under a CHK will immediately be detected by the next node or the client. CHKs also reduce the redundancy of data since the same data will have the same CHK and when multiple sites reference the same large files, they can reference to the same CHK.

SSKs are based on public-key cryptography. Currently Freenet uses the DSA algorithm. Documents inserted under SSKs are signed by the inserter, and this signature can be verified by every node to ensure that the data is not tampered with. SSKs can be used to establish a verifiable pseudonymous identity on Freenet, and allow for multiple documents to be inserted securely by a single person. Files inserted with an SSK are effectively immutable, since inserting a second file with the same name can cause collisions. USKs resolve this by adding a version number to the keys which is also used for providing update notification for keys registered as bookmarks in the web interface. Another subtype of the SSK is the Keyword Signed Key, or KSK, in which the key pair is generated in a standard way from a simple human-readable string. Inserting a document using a KSK allows the document to be retrieved and decrypted if and only if the requester knows the human-readable string; this allows for more convenient (but less secure) URIs for users to refer to.

Scalability

A network is said to be scalable if its performance does not deteriorate even if the network is very large. The scalability of Freenet is being evaluated, but similar architectures have been shown to scale logarithmically. This work indicates that Freenet can find data in O ( log 2 n ) {\displaystyle O(\log ^{2}n)} hops on a small-world network (which includes both opennet and darknet style Freenet networks), when ignoring the caching which could improve the scalability for popular content. However, this scalability is difficult to test without a very large network. Furthermore, the security features inherent to Freenet make detailed performance analysis (including things as simple as determining the size of the network) difficult to do accurately. As of now, the scalability of Freenet has yet to be tested.

Darknet versus opennet

As of version 0.7, Freenet supports both "darknet" and "opennet" connections. Opennet connections are made automatically by nodes with opennet enabled, while darknet connections are manually established between users that know and trust each other. Freenet developers describe the trust needed as "will not crack their Freenet node". Opennet connections are easy to use, but darknet connections are more secure against attackers on the network, and can make it difficult for an attacker (such as an oppressive government) to even determine that a user is running Freenet in the first place.

The core innovation in Freenet 0.7 is to allow a globally scalable darknet, capable (at least in theory) of supporting millions of users. Previous darknets, such as WASTE, have been limited to relatively small disconnected networks. The scalability of Freenet is made possible by the fact that human relationships tend to form small-world networks, a property that can be exploited to find short paths between any two people. The work is based on a speech given at DEF CON 13 by Ian Clarke and Swedish mathematician Oskar Sandberg. Furthermore, the routing algorithm is capable of routing over a mixture of opennet and darknet connections, allowing people who have only a few friends using the network to get the performance from having sufficient connections while still receiving some of the security benefits of darknet connections. This also means that small darknets where some users also have opennet connections are fully integrated into the whole Freenet network, allowing all users access to all content, whether they run opennet, darknet, or a hybrid of the two, except for darknet pockets connected only by a single hybrid node.

Tools and applications

Screenshot of Frost running on Microsoft Windows

Unlike many other P2P applications Freenet does not provide comprehensive functionality itself. Freenet is modular and features an API called Freenet Client Protocol (FCP) for other programs to use to implement services such as message boards, file sharing, or online chat.

Communication

Freenet Messaging System (FMS)

FMS was designed to address problems with Frost such as denial of service attacks and spam. Users publish trust lists, and each user downloads messages only from identities they trust and identities trusted by identities they trust. FMS is developed anonymously and can be downloaded from the FMS freesite within Freenet. It does not have an official site on the normal Internet. It features random post delay, support for many identities, and a distinction between trusting a user's posts and trusting their trust list. It is written in C++ and is a separate application from Freenet which uses the Freenet Client Protocol (FCP) to interface with Freenet.

Frost

Frost includes support for convenient file sharing, but its design is inherently vulnerable to spam and denial of service attacks. Frost can be downloaded from the Frost home page on SourceForge, or from the Frost freesite within Freenet. It is not endorsed by the Freenet developers. Frost is written in Java and is a separate application from Freenet.

Sone

Sone provides a simpler interface inspired by Facebook with public anonymous discussions and image galleries. It provides an API for control from other programs is also used to implement a comment system for static websites in the regular internet.

Utilities

jSite

jSite is a tool to upload websites. It handles keys and manages uploading files.

Infocalypse

Infocalypse is an extension for the distributed revision control system Mercurial. It uses an optimized structure to minimize the number of requests to retrieve new data, and allows supporting a repository by securely reuploading most parts of the data without requiring the owner's private keys.

Libraries

FCPLib

FCPLib (Freenet Client Protocol Library) aims to be a cross-platform natively compiled set of C++-based functions for storing and retrieving information to and from Freenet. FCPLib supports Windows NT/2K/XP, Debian, BSD, Solaris, and macOS.

lib-pyFreenet

lib-pyFreenet exposes Freenet functionality to Python programs. Infocalypse uses it.

Vulnerabilities

Law enforcement agencies have claimed to have successfully infiltrated Freenet opennet in order to deanonymize users but no technical details have been given to support these allegations. One report stated that, "A child-porn investigation focused on ... when the authorities were monitoring the online network, Freenet." A different report indicated arrests may have been based on the BlackICE project leaks, that are debunked for using bad math and for using an incorrectly calculated false positives rate and a false model.

A court case in the Peel Region of Ontario, Canada R. v. Owen, 2017 ONCJ 729 (CanLII), illustrated that law enforcement do in fact have a presence, after Peel Regional Police located who had been downloading illegal material on the Freenet network. The court decision indicates that a Canadian Law Enforcement agency operates nodes running modified Freenet software in the hope of determining who is requesting illegal material.

  • Routing Table Insertion (RTI) Attack

Notability

Freenet has had significant publicity in the mainstream press, including articles in The New York Times, and coverage on CNN, 60 Minutes II, the BBC, The Guardian, and elsewhere.

Freenet received the SUMA-Award 2014 for "protection against total surveillance".

Freesite

A "freesite" is a site hosted on the Freenet network. Because it contains only static content, it cannot contain any active content like server-side scripts or databases. Freesites are coded in HTML and support as many features as the browser viewing the page allows; however, there are some exceptions where the Freenet software will remove parts of the code that may be used to reveal the identity of the person viewing the page (making a page access something on the internet, for example).

See also

Comparable software

References

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