Re: Researchers from the University of Michigan identified of 86% of live Tor "bridges" with a single scan?

2013 Researchers from the [[University of Michigan]] developed a network scanner allowing identification of 86% of live Tor "bridges" with a single scan.<ref name="twe-zmap"/> <ref name="twe-zmap">{{cite web|url=http://www.techweekeurope.co.uk/news/zmap-internet-scan-zero-day-125374|title=Zmap's Fast Internet Scan Tool Could Spread Zero Days In Minutes|last=Judge|first=Peter|date=20 August 2013|website=TechWeek Europe|url-status=dead|archive-url=https://web.archive.org/web/20130824142042/http://www.techweekeurope.co.uk/news/zmap-internet-scan-zero-day-125374|archive-date=24 August 2013}}</ref> {{Short description|Free and open-source anonymity network based on onion routing}} {{About|the software and anonymity network|the software's organization|The Tor Project}} {{Other uses|Tor (disambiguation)}} {{Pp-pc1}} {{Use dmy dates|date=January 2020}} {{Multiple issues| {{More citations needed|date=December 2021}} {{Duplication|date=August 2022|dupe=#Bad apple attack}} {{POV|date=February 2021}} }} {{Infobox software | name = Tor | logo = [[File:Tor-logo-2011-flat.svg|150px]] | logo caption = [[The Tor Project]] logo | screenshot = [[File:Tor November 2021.png|250px]] | caption = The [[#Tor Browser|Tor Browser]] default homepage | collapsible = | developer = [[The Tor Project]] | released = {{Start date and age|2002|9|20|df=y}}<ref name="prealpha" /> | ver layout = stacked | discontinued = | programming language = [[C (programming language)|C]],<ref name="openhub-tor" /> [[Python programming language|Python]], [[Rust (programming language)|Rust]]<ref>{{cite web | date=2022| title=Announcing Arti, a pure-Rust Tor implementation| url=https://blog.torproject.org/announcing-arti}}</ref> | operating system = [[Unix-like]], ([[Android operating system|Android]], [[Linux]], [[BSD]], [[macOS]]), [[Microsoft Windows]], [[IOS]]. | platform = | size = {{Nowrap|50–55 MB}}<!-- Stand-alone version! Tor Browser has its own infobox further down. --> | language = | genre = [[Overlay network]], [[mix network]], [[onion routing|onion router]], [[Anonymity application]] | license = [[BSD licenses#3-clause license ("BSD License 2.0", "Revised BSD License", "New BSD License", or "Modified BSD License")|BSD 3-clause license]]<ref name="LICENSE - Tor">{{cite web |title=LICENSE – Tor's source code |url=https://gitweb.torproject.org/tor.git/tree/LICENSE |access-date=15 May 2018 |website=tor |archive-date=5 November 2018 |archive-url=https://web.archive.org/web/20181105121901/https://gitweb.torproject.org/tor... |url-status=live }}</ref> | website = {{URL|torproject.org}} }} {{File sharing sidebar}} '''Tor''', short for '''The Onion Router''',<ref>{{cite web|url=https://www.bbc.com/news/technology-29987379|title=Dark net raids were 'overblown' by police, says Tor Project|last=Lee|first=Dave|work=[[BBC]]|date=10 November 2014|access-date=18 June 2022}}</ref> is<!--software is a mass noun in English, do not put "a" here--> [[free and open-source software]] for enabling [[Anonymity|anonymous communication]].<ref>{{Cite journal|last=Schmucker|first=Niklas|title=Web tracking|journal=SNET2 Seminar Paper-Summer Term}}</ref> It directs [[Internet]] traffic through a free, worldwide, volunteer [[overlay network]], consisting of more than seven thousand relays,<ref name="torstatus" /> to conceal a user's location and usage from anyone performing [[Computer and network surveillance#Network surveillance|network surveillance]] or [[Traffic analysis#In computer security|traffic analysis]].<ref>{{Cite journal |last1=McCoy |first=Damon |author2=Kevin Bauer |author3=Dirk Grunwald |author4=Tadayoshi Kohno |author5=Douglas Sicker |title=Shining light in dark places: Understanding the Tor network |journal=International Symposium on Privacy Enhancing Technologies Symposium}}</ref> Using Tor makes it more difficult to trace a user's Internet activity. Tor's intended use is to protect the personal privacy of its users, as well as their freedom and ability to communicate confidentially through [[IP address]] anonymity using Tor exit nodes.<ref>{{cite web |title=ABOUT TOR BROWSER {{!}} Tor Project {{!}} Tor Browser Manual |url=https://tb-manual.torproject.org/about/#:~:text=Tor%20is%20a%20network%20of,.... |access-date=2022-04-27 |website=tb-manual.torproject.org}}</ref> ==History== The core principle of Tor, [[onion routing]], was developed in the mid-1990s by [[United States Naval Research Laboratory]] employees, [[mathematician]] [[Paul Syverson]], and [[computer scientist]]s [[G. Mike Reed|Michael G. Reed]] and David Goldschlag, to protect [[United States Intelligence Community|American intelligence]] communications online.<ref name=bw-tor-vs /> Onion routing is implemented by means of [[encryption]] in the [[application layer]] of the [[communication protocol]] stack, nested like the layers of an [[onion]]. The [[alpha version]] of Tor, developed by Syverson and computer scientists [[Roger Dingledine]] and [[Nick Mathewson]] and then called The Onion Routing project (which was later given the acronym "Tor"), was launched on 20 September 2002.<ref name="tor-history">{{cite web |title=History |url=https://www.torproject.org/about/history/ |website=Tor Project |access-date=5 June 2021}}</ref><ref name="torproject-faq" /> The first public release occurred a year later.<ref>{{Cite mailing list|mailing-list=tor-dev|last=Dingledine|first=Rogert|date=8 October 2003|title=Tor is free|publisher=Tor Project|url=https://lists.torproject.org/pipermail/tor-dev/2003-October/002185.html|access-date=23 September 2016|archive-date=13 February 2017|archive-url=https://web.archive.org/web/20170213031700/https://lists.torproject.org/pipermail/tor-dev/2003-October/002185.html|url-status=live}}</ref> {{Anchor|Tor project}} In 2004, the Naval Research Laboratory released the code for Tor under a free license, and the [[Electronic Frontier Foundation]] (EFF) began funding Dingledine and Mathewson to continue its development.<ref name="tor-history" /> In 2006, Dingledine, Mathewson, and five others founded [[The Tor Project]], a [[Massachusetts]]-based [[501(c)(3)]] research-education [[nonprofit organization]] responsible for maintaining Tor. The EFF acted as The Tor Project's [[Fiscal sponsorship|fiscal sponsor]] in its early years, and early financial supporters included the U.S. [[Bureau of Democracy, Human Rights, and Labor]] and [[International Broadcasting Bureau]], [[Internews]], [[Human Rights Watch]], the [[University of Cambridge]], [[Google]], and Netherlands-based [[NLnet|Stichting NLnet]].<ref>{{cite web|date=2009|title=Tor Project Form 990 2008|url=https://www.torproject.org/about/findoc/2008-TorProject-Form990.pdf|url-status=dead|archive-url=https://web.archive.org/web/20170629102518/https://www.torproject.org/about/findoc/2008-TorProject-Form990.pdf|archive-date=29 June 2017|access-date=30 August 2014|website=Tor Project}}</ref><ref>{{cite web|date=2010|title=Tor Project Form 990 2009|url=https://www.torproject.org/about/findoc/2009-TorProject-Form990andPC.pdf|url-status=dead|archive-url=https://web.archive.org/web/20170629102506/https://www.torproject.org/about/findoc/2009-TorProject-Form990andPC.pdf|archive-date=29 June 2017|access-date=30 August 2014|website=Tor Project}}</ref> [[File:Geographies of Tor.png|thumb|A [[cartogram]] illustrating Tor usage]] Over the course of its existence, various Tor [[#Weaknesses|weaknesses]] have been discovered and occasionally exploited. Attacks against Tor are an active area of academic research<ref>{{cite web|last=Goodin|first=Dan|date=22 July 2014|title=Tor developers vow to fix bug that can uncloak users|url=https://arstechnica.com/security/2014/07/tor-developers-vow-to-fix-bug-that-can-uncloak-users/|url-status=live|archive-url=https://web.archive.org/web/20170708090704/https://arstechnica.com/security/2014/07/tor-developers-vow-to-fix-bug-that-can-uncloak-users/|archive-date=8 July 2017|access-date=15 June 2017|website=[[Ars Technica]]}}</ref><ref>{{cite web|title=Selected Papers in Anonymity|url=http://freehaven.net/anonbib/#2014|url-status=live|archive-url=https://web.archive.org/web/20180712134223/https://www.freehaven.net/anonbib/#2014|archive-date=12 July 2018|access-date=26 October 2005|website=Free Haven}}</ref> that is welcomed by The Tor Project itself.<ref>{{cite web|title=Tor Research Home|url=https://research.torproject.org/|url-status=live|archive-url=https://web.archive.org/web/20180626053025/https://research.torproject.org/|archive-date=26 June 2018|access-date=31 July 2014|publisher=torproject.org}}</ref> == Usage == {{Further|Dark web}} {{Hidden services 2015}} {{Hidden services 2016}} Tor enables its users to surf the Internet, chat and send instant messages anonymously, and is used by a wide variety of people for both licit and illicit purposes.<ref>{{Cite magazine |last=Zetter |first=Kim |date=17 May 2005 |title=Tor Torches Online Tracking |magazine=Wired |url=http://archive.wired.com/politics/security/news/2005/05/67542?currentPage=al... |access-date=30 August 2014 |archive-date=26 July 2014 |archive-url=https://web.archive.org/web/20140726025108/http://archive.wired.com/politics... |url-status=live }}</ref> Tor has, for example, been used by criminal enterprises, [[hacktivism]] groups, and law enforcement agencies at cross purposes, sometimes simultaneously;<ref name="cso-black-market" /><ref name="muckrock-hunting-porn" /> likewise, agencies within the U.S. government variously fund Tor (the [[United States Department of State|U.S. State Department]], the National Science Foundation, and – through the Broadcasting Board of Governors, which itself partially funded Tor until October 2012 – [[Radio Free Asia]]) and seek to subvert it.<ref name="guardian-nsa-target" /><ref name="bw-tor-vs" /> Tor is not meant to completely solve the issue of anonymity on the web. Tor is not designed to completely erase tracking but instead to reduce the likelihood for sites to trace actions and data back to the user.<ref>{{cite web |title=Tor: Overview |url=https://www.torproject.org/about/overview.html.en |website=The Tor Project |access-date=29 April 2015 |archive-date=6 June 2015 |archive-url=https://web.archive.org/web/20150606002957/https://www.torproject.org/about/... |url-status=live }}</ref> Tor is also used for illegal activities. These can include privacy protection or censorship circumvention,<ref name="scm-egyptians" /> as well as distribution of child abuse content, drug sales, or malware distribution.<ref name=":1">{{Cite journal |last1=Jardine |first1=Eric |last2=Lindner |first2=Andrew M. |last3=Owenson |first3=Gareth |date=2020-12-15 |title=The potential harms of the Tor anonymity network cluster disproportionately in free countries |journal=Proceedings of the National Academy of Sciences |language=en |volume=117 |issue=50 |pages=31716–31721 |doi=10.1073/pnas.2011893117 |issn=0027-8424 |pmid=33257555 |pmc=7749358 |bibcode=2020PNAS..11731716J |doi-access=free }}</ref> Tor has been described by ''[[The Economist]]'', in relation to [[Bitcoin]] and [[Silk Road (marketplace)|Silk Road]], as being "a dark corner of the web".<ref name="economist-bitcoin" /> It has been targeted by the American [[National Security Agency]] and the British [[GCHQ]] [[signals intelligence]] agencies, albeit with marginal success,<ref name="guardian-nsa-target" /> and more successfully by the British [[National Crime Agency]] in its Operation Notarise.<ref>{{cite web |last1=Boiten |first1=Eerke |last2=Hernandez-Castro |first2=Julio |date=28 July 2014 |title=Can you really be identified on Tor or is that just what the cops want you to believe? |url=http://phys.org/news/2014-07-tor-cops.html |website=Phys.org |access-date=31 July 2014 |archive-date=1 February 2019 |archive-url=https://web.archive.org/web/20190201224220/https://phys.org/news/2014-07-tor... |url-status=live }}</ref> At the same time, GCHQ has been using a tool named "Shadowcat" for "end-to-end encrypted access to VPS over SSH using the Tor network".<ref>{{cite web |date=14 July 2014 |title=JTRIG Tools and Techniques |url=https://firstlook.org/theintercept/document/2014/07/14/jtrig-tools-technique... |website=[[The Intercept]] |access-date=14 July 2014 |archive-date=14 July 2014 |archive-url=https://web.archive.org/web/20140714224430/https://firstlook.org/theintercep... |url-status=live }}</ref><ref>{{cite web |date=5 July 2012 |title=Document from an internal GCHQ wiki lists tools and techniques developed by the Joint Threat Research Intelligence Group |url=https://www.documentcloud.org/documents/1217406-jtrigall.html#document/p4gz |access-date=30 July 2014 |website=documentcoud.org |archive-date=8 August 2014 |archive-url=https://web.archive.org/web/20140808040612/https://www.documentcloud.org/doc... |url-status=live }}</ref> Tor can be used for anonymous defamation, unauthorized [[news leak]]s of sensitive information, [[copyright infringement]], distribution of illegal sexual content,<ref name="bbr-cleaning-up" /><ref name="jones-forensics" /><ref name="gawker-kiddie-porn" /> selling [[controlled substance]]s,<ref name="gawker-any-drug" /> weapons, and stolen credit card numbers,<ref>{{Cite news |last=Steinberg |first=Joseph |date=8 January 2015 |title=How Your Teenage Son or Daughter May Be Buying Heroin Online |work=Forbes |url=https://www.forbes.com/sites/josephsteinberg/2015/01/08/how-your-children-ca... |access-date=6 February 2015 |archive-date=10 February 2015 |archive-url=https://web.archive.org/web/20150210015157/http://www.forbes.com/sites/josep... |url-status=live }}</ref> [[money laundering]],<ref name="ars-feds-narcotics" /> bank fraud,<ref>{{cite web |date=5 December 2014 |title=Treasury Dept: Tor a Big Source of Bank Fraud |url=http://krebsonsecurity.com/2014/12/treasury-dept-tor-a-big-source-of-bank-fr... |website=Krebs on Security |access-date=7 December 2014 |archive-date=3 February 2019 |archive-url=https://web.archive.org/web/20190203162229/https://krebsonsecurity.com/2014/... |url-status=live }}</ref> [[credit card fraud]], [[identity theft]] and the exchange of [[counterfeit currency]];<ref>{{cite web |last=Farivar |first=Cyrus |date=3 April 2015 |title=How a $3.85 latte paid for with a fake $100 bill led to counterfeit kingpin's downfall |url=https://arstechnica.com/tech-policy/2015/04/how-a-3-85-latte-paid-for-with-a... |access-date=19 April 2015 |website=Ars Technica |archive-date=18 April 2015 |archive-url=https://web.archive.org/web/20150418023540/http://arstechnica.com/tech-polic... |url-status=live }}</ref> the [[black market]] utilizes the Tor infrastructure, at least in part, in conjunction with Bitcoin.<ref name="cso-black-market" /> It has also been used to brick [[Internet of things|IoT]] devices.<ref name="BrickerBot">{{cite web |last=Cimpanu |first=Catalin |date=6 April 2017 |title=New Malware Intentionally Bricks IoT Devices |url=https://www.bleepingcomputer.com/news/security/new-malware-intentionally-bri... |website=BleepingComputer |access-date=7 April 2017 |archive-date=19 February 2019 |archive-url=https://web.archive.org/web/20190219020834/https://www.bleepingcomputer.com/... |url-status=live }}</ref> In its complaint against [[Ross William Ulbricht]] of [[Silk Road (marketplace)|Silk Road]], the US [[Federal Bureau of Investigation]] acknowledged that Tor has "known legitimate uses".<ref name="compaint-ulbricht" /><ref name="eff-silk-road" /> According to [[CNET]], Tor's anonymity function is "endorsed by the [[Electronic Frontier Foundation]] (EFF) and other civil liberties groups as a method for [[whistleblower]]s and human rights workers to communicate with journalists".<ref name="cnet-arrested" /> EFF's Surveillance Self-Defense guide includes a description of where Tor fits in a larger strategy for protecting privacy and anonymity.<ref name="eff-ssd-tor" /> In 2014, the EFF's [[Eva Galperin]] told ''[[Businessweek]]'' that "Tor's biggest problem is press. No one hears about that time someone wasn't [[stalking|stalked]] by their abuser. They hear how somebody got away with downloading child porn."<ref name="thecable" /> The Tor Project states that Tor users include "normal people" who wish to keep their Internet activities private from websites and advertisers, people concerned about cyber-spying, and users who are evading censorship such as activists, journalists, and military professionals. {{As of |2013|11|}}, Tor had about four million users.<ref>{{Cite news |last=Dredge |first=Stuart |date=5 November 2013 |title=What is Tor? A beginner's guide to the privacy tool |work=[[The Guardian]] |url=https://www.theguardian.com/technology/2013/nov/05/tor-beginners-guide-nsa-b... |access-date=30 August 2014 |archive-date=15 August 2014 |archive-url=https://web.archive.org/web/20140815233728/http://www.theguardian.com/techno... |url-status=live }}</ref> According to the ''Wall Street Journal'', in 2012 about 14% of Tor's traffic connected from the United States, with people in "Internet-censoring countries" as its second-largest user base.<ref>{{Cite news |last=Fowler |first=Geoffrey A. |date=17 December 2012 |title=Tor: An Anonymous, And Controversial, Way to Web-Surf |work=The Wall Street Journal |url=https://online.wsj.com/news/articles/SB1000142412788732467720457818538237714... |access-date=30 August 2014 |archive-date=19 February 2014 |archive-url=https://web.archive.org/web/20140219235003/http://online.wsj.com/news/articl... |url-status=live }}</ref> Tor is increasingly used by victims of [[domestic violence]] and the [[social worker]]s and agencies that assist them, even though shelter workers may or may not have had professional training on cyber-security matters.<ref name="Where Domestic Violence and Cybersecurity Intersect">{{cite web |last=Tveten |first=Julianne |date=12 April 2017 |title=Where Domestic Violence and Cybersecurity Intersect |url=https://rewire.news/article/2017/04/12/domestic-violence-cybersecurity-inter... |access-date=9 August 2017 |website=Rewire |archive-date=10 August 2017 |archive-url=https://web.archive.org/web/20170810052253/https://rewire.news/article/2017/... |url-status=live }}</ref> Properly deployed, however, it precludes digital stalking, which has increased due to the prevalence of digital media in contemporary [[online]] life.<ref name="boston-domestic-abuse" /> Along with [[SecureDrop]], Tor is used by news organizations such as ''[[The Guardian]]'', ''[[The New Yorker]]'', [[ProPublica]] and ''[[The Intercept]]'' to protect the privacy of whistleblowers.<ref>{{Cite news |last=Ellis |first=Justin |date=5 June 2014 |title=The Guardian introduces SecureDrop for document leaks |work=Nieman Journalism Lab |url=http://www.niemanlab.org/2014/06/the-guardian-introduces-securedrop-for-docu... |access-date=30 August 2014 |archive-date=17 August 2014 |archive-url=https://web.archive.org/web/20140817181552/http://www.niemanlab.org/2014/06/... |url-status=live }}</ref> In March 2015, the [[Parliamentary Office of Science and Technology]] released a briefing which stated that "There is widespread agreement that banning online anonymity systems altogether is not seen as an acceptable policy option in the U.K." and that "Even if it were, there would be technical challenges." The report further noted that Tor "plays only a minor role in the online viewing and distribution of indecent images of children" (due in part to its inherent latency); its usage by the [[Internet Watch Foundation]], the utility of its onion services for [[whistleblower]]s, and its circumvention of the [[Great Firewall]] of China were touted.<ref name="The Daily Dot">{{cite web |last=O'Neill |first=Patrick Howell |date=9 March 2015 |title=U.K. Parliament says banning Tor is unacceptable and impossible |url=http://www.dailydot.com/politics/uk-briefing-tor-child-abuse-minor-role/ |access-date=19 April 2015 |website=The Daily Dot |archive-date=2 April 2015 |archive-url=https://web.archive.org/web/20150402091025/http://www.dailydot.com/politics/... |url-status=live }}</ref> Tor's executive director, Andrew Lewman, also said in August 2014 that agents of the NSA and the GCHQ have anonymously provided Tor with bug reports.<ref>{{Cite news |last=Kelion |first=Leo |date=22 August 2014 |title=NSA and GCHQ agents 'leak Tor bugs', alleges developer |work=BBC News |url=https://www.bbc.com/news/technology-28886462 |access-date=21 July 2018 |archive-date=2 February 2019 |archive-url=https://web.archive.org/web/20190202041855/https://www.bbc.com/news/technolo... |url-status=live }}</ref> The Tor Project's FAQ offers supporting reasons for the EFF's endorsement: {{blockquote|Criminals can already do bad things. Since they're willing to break laws, they already have lots of options available that provide better privacy than Tor provides... Tor aims to provide protection for ordinary people who want to follow the law. Only criminals have privacy right now, and we need to fix that... So yes, criminals could in theory use Tor, but they already have better options, and it seems unlikely that taking Tor away from the world will stop them from doing their bad things. At the same time, Tor and other privacy measures can fight identity theft, physical crimes like stalking, and so on.|source=Tor Project FAQ<ref name="torproject-faq-abuse" />}} ==Operation== {{Multiple image | image1 = How Tor Works 2.svg | caption1 = [[Infographic]] about how Tor works, by [[Electronic Frontier Foundation|EFF]] }} Tor aims to conceal its users' identities and their online activity from surveillance and traffic analysis by separating identification and routing. It is an implementation of [[onion routing]], which encrypts and then randomly bounces communications through a network of relays run by volunteers around the globe. These onion routers employ [[encryption]] in a multi-layered manner (hence the onion metaphor) to ensure [[perfect forward secrecy]] between relays, thereby providing users with anonymity in a network location. That anonymity extends to the hosting of censorship-resistant content by Tor's anonymous onion service feature.<ref name="usenix-design" /> Furthermore, by keeping some of the entry relays (bridge relays) secret, users can evade [[Internet censorship]] that relies upon blocking public Tor relays.<ref name="torproject-bridges" /> Because the [[IP address]] of the sender and the recipient are not ''both'' in [[cleartext]] at any hop along the way, anyone eavesdropping at any point along the communication channel cannot directly identify both ends. Furthermore, to the recipient, it appears that the last Tor [[Node (networking)|node]] (called the exit node), rather than the sender, is the originator of the communication. ===Originating traffic=== [[File:EtherApeTorScreenShot.png|thumb|A visual depiction of the traffic between some Tor relay [[Node (networking)|nodes]] from the open-source packet sniffing program [[EtherApe]]]] A Tor user's [[SOCKS]]-aware applications can be configured to direct their network traffic through a Tor instance's SOCKS interface, which is listening on TCP port 9050 (for standalone Tor) or 9150 (for Tor Browser bundle) at [[localhost]].<ref>{{cite web |title=TorPCAP – Tor Network Forensics |url=https://www.netresec.com/?page=Blog&month=2018-12&post=TorPCAP---Tor-Network-Forensics |access-date=12 December 2018 |website=Netresec |date = 12 December 2018|archive-date=12 December 2018 |archive-url=https://web.archive.org/web/20181212201750/https://www.netresec.com/?page=Blog&month=2018-12&post=TorPCAP---Tor-Network-Forensics |url-status=live }}</ref> Tor periodically creates virtual circuits through the Tor network through which it can [[multiplexing|multiplex]] and onion-route that traffic to its destination. Once inside a Tor network, the traffic is sent from router to router along the circuit, ultimately reaching an exit node at which point the [[cleartext]] packet is available and is forwarded on to its original destination. Viewed from the destination, the traffic appears to originate at the Tor exit node. [[File:Tor-non-exit-relay-bandwidth-usage.jpg|thumb|A Tor non-exit relay with a maximum output of 239.69 kbit/s]] Tor's application independence sets it apart from most other anonymity networks: it works at the [[Transmission Control Protocol]] (TCP) stream level. Applications whose traffic is commonly anonymized using Tor include [[Internet Relay Chat]] (IRC), [[instant messaging]], and [[World Wide Web]] browsing. {{Anchor|Hidden services}} ===Onion services=== {{See also|List of Tor onion services}} {{Further|Dark web}} Tor can also provide anonymity to websites and other servers. Servers configured to receive inbound connections only through Tor are called '''onion services''' (formerly, '''hidden services''').<ref>{{cite web |last=Winter |first=Philipp |title=How Do Tor Users Interact With Onion Services? |url=https://nymity.ch/onion-services/pdf/sec18-onion-services.pdf |access-date=27 December 2018 |archive-date=28 December 2018 |archive-url=https://web.archive.org/web/20181228035314/https://nymity.ch/onion-services/... |url-status=live }}</ref> Rather than revealing a server's IP address (and thus its network location), an onion service is accessed through its [[.onion|onion address]], usually via the [[#Tor Browser|Tor Browser]]. The Tor network understands these addresses by looking up their corresponding [[public key]]s and ''introduction points'' from a [[distributed hash table]] within the network. It can route data to and from onion services, even those hosted behind [[firewall (computing)|firewalls]] or [[network address translator]]s (NAT), while preserving the anonymity of both parties. Tor is necessary to access these onion services.<ref name="torproject-conf-hidden" /> Onion services were first specified in 2003<ref>{{cite web |last=Mathewson |first=Nick |title=Add first draft of rendezvous point document |url=https://gitweb.torproject.org/tor.git/commit/?id=3d538f6d702937c23bec33b3bdd... |access-date=23 September 2016 |website=Tor Source Code |archive-date=15 November 2018 |archive-url=https://web.archive.org/web/20181115205018/https://gitweb.torproject.org/tor... |url-status=live }}</ref> and have been deployed on the Tor network since 2004.<ref name="or-locating" /> Other than the database that stores the onion service descriptors,<ref name="torproject-hidden" /> Tor is decentralized by design; there is no direct readable list of all onion services, although a number of onion services catalog publicly known onion addresses.{{Citation needed|date=April 2022}} Because onion services route their traffic entirely through the Tor network, connection to an onion service is encrypted end-to-end and not subject to eavesdropping. There are, however, security issues involving Tor onion services. For example, services that are reachable through Tor onion services ''and'' the public Internet are susceptible to correlation attacks and thus not perfectly hidden. Other pitfalls include misconfigured services (e.g. identifying information included by default in web server error responses), uptime and downtime statistics, intersection attacks, and user error.<ref name="torproject-hidden" /><ref name="register-embassy-passwd" /> The [[open-source software|open source]] OnionScan program, written by independent security researcher [[Sarah Jamie Lewis]], comprehensively examines onion services for numerous flaws and vulnerabilities.<ref name="OnionScan">{{cite web |last=Cox |first=Joseph |date=6 April 2016 |title=A Tool to Check If Your Dark Web Site Really Is Anonymous: 'OnionScan' will probe dark web sites for security weaknesses |url=https://motherboard.vice.com/en_us/article/kb7bg3/onionscan-checks-if-your-d... |access-date=7 July 2017 |website=Motherboard |archive-date=16 August 2017 |archive-url=https://web.archive.org/web/20170816012653/https://motherboard.vice.com/en_u... |url-status=live }}</ref> (Lewis has also pioneered the field of "Onion Dildonics", [[sex toy]]s which make use of Tor through the [[Ricochet (software)|Ricochet]] protocol)<ref name="Onion Dildonics">{{Cite magazine |last=Burgess |first=Matt |date=3 February 2018 |title=Smart Dildos and Vibrators Keep Getting Hacked – But Tor Could Be the Answer to Safer Connected Sex |url=https://www.wired.co.uk/article/sex-toy-bluetooth-hacks-security-fix |magazine=Wired UK |access-date=9 February 2018 |archive-date=9 February 2018 |archive-url=https://web.archive.org/web/20180209182430/https://www.wired.co.uk/article/s... |url-status=live }}</ref> Onion services can also be accessed from a standard web browser without [[client-side]] connection to the Tor network, using services like [[Tor2web]].<ref>{{Cite magazine |last=Zetter |first=Kim |date=12 December 2008 |title=New Service Makes Tor Anonymized Content Available to All |url=https://www.wired.com/threatlevel/2008/12/tor-anonymized/ |magazine=Wired |access-date=22 February 2014 |archive-date=18 March 2014 |archive-url=https://web.archive.org/web/20140318042302/http://www.wired.com/threatlevel/... |url-status=live }}</ref> Popular sources of [[.onion]] links include [[Pastebin.com|Pastebin]], [[Twitter]], [[Reddit]], and other [[Internet forum]]s.<ref>{{Cite news |last=Koebler |first=Jason |date=23 February 2015 |title=The Closest Thing to a Map of the Dark Net: Pastebin |work=Motherboard |url=http://motherboard.vice.com/read/the-closest-thing-to-a-map-of-the-dark-net-... |access-date=14 July 2015 |archive-date=22 December 2016 |archive-url=https://web.archive.org/web/20161222205738/http://motherboard.vice.com/read/... |url-status=live }}</ref> ===Nyx status monitor=== Nyx (formerly ARM) is a [[Command-line interface|command-line]] status monitor written in [[Python (programming language)|Python]] for Tor.<ref>{{cite web |title=Nyx |url=https://nyx.torproject.org/ |website=nyx.torproject.org |language=en |access-date=19 June 2018 |archive-date=26 January 2019 |archive-url=https://web.archive.org/web/20190126070143/https://nyx.torproject.org/ |url-status=live }}</ref><ref>{{cite web |title=Ubuntu Manpage: arm – Terminal Tor status monitor |url=http://manpages.ubuntu.com/manpages/precise/man1/arm.1.html |website=Ubuntu.com |access-date=20 April 2015 |archive-date=20 June 2018 |archive-url=https://web.archive.org/web/20180620002955/http://manpages.ubuntu.com/manpag... |url-status=live }}</ref> This functions much like [[Top (software)|top]] does for system usage, providing real time statistics for: * resource usage (bandwidth, CPU, and memory usage) * general relaying information (nickname, fingerprint, flags, or/dir/controlports) * event log with optional [[Regular expression|regex]] filtering and [[Data deduplication|deduplication]] * connections correlated against Tor's consensus data (IP address, connection types, relay details, etc.) * torrc configuration file with [[syntax highlighting]] and validation Most of Nyx's attributes are configurable through an optional [[configuration file]]. It runs on any platform supported by [[Curses (programming library)|curses]] including [[Linux]], [[macOS]], and other [[Unix-like]] variants. The project began in the summer of 2009,<ref name="arm introductory blog posting">{{cite web |title=Summer Conclusion (ARM Project) |url=https://blog.torproject.org/blog/summer-conclusion-arm-project |access-date=19 April 2015 |website=torproject.org |archive-date=20 April 2015 |archive-url=https://web.archive.org/web/20150420152618/https://blog.torproject.org/blog/... |url-status=live }}</ref><ref name="arm interview">{{cite web |title=Interview with Damien Johnson by Brenno Winter |url=https://www.atagar.com/arm/resources/HFM_INT_0001.mp3 |url-status=dead |archive-url=https://web.archive.org/web/20141004085010/https://www.atagar.com/arm/resour... |archive-date=4 October 2014 |access-date=4 June 2016 |website=atagar.com}}</ref> and since 18 July 2010 it has been an official part of the Tor Project. It is [[free software]], available under the [[GNU General Public License]].<ref name=license/> ==Weaknesses== {{Update|section|date=September 2020}} Like all current [[latency (engineering)|low-latency]] [[anonymity network]]s, Tor cannot and does not attempt to protect against monitoring of traffic at the boundaries of the Tor network (i.e., the traffic entering and exiting the network). While Tor does provide protection against [[traffic analysis]], it cannot prevent traffic confirmation (also called ''end-to-end correlation'').<ref name="torproject-one-cell" /><ref name="torproject-fail-both-ends" /> A 2009 study{{By whom|date=April 2022}} revealed that Tor and the alternative network system [[Java Anon Proxy|JonDonym]] (Java Anon Proxy, JAP) are considered more resilient to website fingerprinting techniques than other [[tunneling protocol]]s.<ref>{{Cite journal |last=Herrmann |first=Dominik |last2=Wendolsky |first2=Rolf |last3=Federrath |first3=Hannes |date=2009 |title=Website fingerprinting |url=http://dx.doi.org/10.1145/1655008.1655013 |journal=Proceedings of the 2009 ACM workshop on Cloud computing security - CCSW '09 |location=New York, New York, USA |publisher=ACM Press |doi=10.1145/1655008.1655013}}</ref> The reason for this is that conventional single-hop [[VPN]] protocols do not need to reconstruct packet data nearly as much as a multi-hop service like Tor or JonDonym. Website fingerprinting yielded greater than 90% accuracy for identifying [[HTTP]] packets on conventional VPN protocols versus Tor which yielded only 2.96% accuracy. However, some protocols like [[OpenSSH]] and [[OpenVPN]] required a large amount of data before HTTP packets were identified.<ref name="ccsw-attacking" /> Researchers from the [[University of Michigan]] developed a network scanner allowing identification of 86% of live Tor "bridges" with a single scan.<ref name="twe-zmap"/> ===Consensus blocking=== Like many decentralized systems, Tor relies on a [[consensus (computer science)|consensus mechanism]] to periodically update its current operating parameters, which for Tor are network parameters like which nodes are good/bad relays, exits, guards, and how much traffic each can handle. Tor's architecture for deciding the consensus relies on a small number of directory authority nodes voting on current network parameters. Currently, there are ten directory authority nodes, and their health is publicly monitored.<ref>{{cite web|url=https://consensus-health.torproject.org/ |title=Consensus health |publisher=Consensus-health.torproject.org |date= |access-date=2022-03-15}}</ref> The IP addresses of the authority nodes are [[hard coded]] into each Tor client. The authority nodes vote every hour to update the consensus, and clients download the most recent consensus on startup.<ref>{{cite web |title=Getting Started with Tor Development |author=George Tankersley |date=2017-10-04 |url=https://blog.gtank.cc/tor-dev-101/ |access-date=16 January 2021 |archive-date=22 January 2021 |archive-url=https://web.archive.org/web/20210122001011/https://blog.gtank.cc/tor-dev-101... |url-status=live }}</ref><ref>{{cite web |url=https://blog.torproject.org/introducing-bastet-our-new-directory-authority |title=Introducing Bastet, Our New Directory Authority |author=tommy |date=2017-11-02 |publisher=[[The Tor Project]] |access-date=16 January 2021 |archive-date=25 November 2020 |archive-url=https://web.archive.org/web/20201125230425/https://blog.torproject.org/intro... |url-status=live }}</ref><ref>{{cite web |title=10 years of collecting Tor directory data |author=Karsten Loesing |date=2014-05-15 |url=https://blog.torproject.org/10-years-collecting-tor-directory-data |publisher=[[The Tor Project]] |access-date=16 January 2021 |archive-date=20 June 2020 |archive-url=https://web.archive.org/web/20200620160219/https://blog.torproject.org/10-ye... |url-status=live }}</ref> A network congestion attack, such as a [[DDoS]], can prevent the consensus nodes from communicating and thus prevent voting to update the consensus.{{Citation needed|date=April 2022}} ===Eavesdropping=== ==== Autonomous system (AS) eavesdropping ==== If the same [[Autonomous system (Internet)|autonomous system]] (AS), responsible for routing packets at least partly, is present on both path segments from a client to entry relay and from exit relay to destination, such an AS can statistically correlate traffic on the entry and exit segments of the path (i.e. traffic confirmation) and potentially infer the destination with which the client communicated. In 2012, LASTor proposed a method to predict a set of potential ASes on these two segments and then avoid choosing this path during the path selection algorithm on the client side. In this paper, they also improve latency by choosing shorter geographical paths between a client and destination.<ref name="LASTor-2012" /> ==== Exit node eavesdropping ==== In September 2007, Dan Egerstad, a Swedish security consultant, revealed he had intercepted usernames and passwords for email accounts by operating and monitoring Tor exit nodes.<ref name="wired-rogue-nodes" /> As Tor cannot encrypt the traffic between an exit node and the target server, any exit node is in a position to capture traffic passing through it that does not use [[end-to-end encryption]] such as [[Secure Sockets Layer]] (SSL) or [[Transport Layer Security]] (TLS). While this may not inherently breach the anonymity of the source, traffic intercepted in this way by malicious Tor exit nodes operators can expose information about the source in either or both of payload and protocol data.<ref name="sf-tor-hack" /> Furthermore, Egerstad is circumspect about the possible subversion of Tor by intelligence agencies:<ref name="smh-hack-of-year" /><!-- Does it still makes sense to list this? This could have been the case 15 years ago, but as of 2022, VPS can be rented very cheaply and support high-speed traffic. -IrrationalBeing --> {{blockquote|If you actually look into where these Tor nodes are hosted and how big they are, some of these nodes cost thousands of dollars each month just to host because they're using lots of bandwidth, they're heavy-duty servers and so on. Who would pay for this and be anonymous?}} In October 2019, a Tor researcher revealed that since at least 2017, there were hundreds of highly suspicious entry, relay, and exit nodes, run by an unknown group, in an unprecedented scale.<ref name=":2">{{cite web|title=Someone Is Running Hundreds of Malicious Servers on the Tor Network and Might Be De-Anonymizing Users |url=https://gizmodo.com/someone-is-running-hundreds-of-malicious-servers-on-the-... |access-date=2021-12-05|website=Gizmodo |date=3 December 2021 |language=en-us}}</ref><ref name=":3">{{cite web|date=2021-12-03|title=A mysterious threat actor is running hundreds of malicious Tor relays |url=https://therecord.media/a-mysterious-threat-actor-is-running-hundreds-of-mal... |access-date=2021-12-05|website=The Record by Recorded Future|language=en}}</ref><ref>{{cite web|date=2021-05-10|title=Over 25% Of Tor Exit Relays Spied On Users' Dark Web Activities |url=https://thehackernews.com/2021/05/over-25-of-tor-exit-relays-are-spying.html |access-date=2021-12-05 |website=The Hacker News |language=en}}</ref> It was alleged that this number of servers could pose the risk of a [[sybil attack]] as it could map Tor users' routes inside the network, increasing risk of deanonymization.<ref>{{cite web | last1 = Paganini | first1 = Pierluigi | date = 2021-12-03 | title = KAX17 threat actor is attempting to deanonymize Tor users running thousands of rogue relays | url = https://cybersecurityworldconference.com/2021/12/03/kax17-threat-actor-is-at... | publisher = cybersecurityworldconference.com | archiveurl = https://web.archive.org/web/20210623001008/https://cybersecurityworldconfere... | archivedate = 2021-06-23 | url-status = live }}</ref><ref name=":2" /><ref name=":3" /> At some point there were about 900 nodes running and by November 2021 about 600 of them were purged.<ref>{{cite web |last=Koppen |first=Georg |date=9 November 2021|title=[tor-relays] Recent rejection of relays |url=https://lists.torproject.org/pipermail/tor-relays/2021-November/019980.html |access-date=2021-12-05}}</ref><ref name=":2" /><ref name=":3" /> Although described as being a deanonymization attempt, the motives and the achievements of this possibly on-going event are still unknown.<ref name=":2" /><ref name=":3" /> ==== Internal communication attack ==== In October 2011, a research team from [[ESIEA (university)|ESIEA]] claimed to have discovered a way to compromise the Tor network by decrypting communication passing over it.<ref name="thn-compromised" /><ref name="01-chercheurs" /> The technique they describe requires creating a map of Tor network nodes, controlling one-third of them, and then acquiring their encryption [[Key (cryptography)|keys]] and algorithm [[Random seed|seeds]]. Then, using these known keys and seeds, they claim the ability to decrypt two encryption layers out of three. They claim to break the third key by a statistical attack. In order to redirect Tor traffic to the nodes they controlled, they used a [[denial-of-service]] attack. A response to this claim has been published on the official Tor Blog stating these rumors of Tor's compromise are greatly exaggerated.<ref name="torproject-rumors-exaggerated" /> ===Traffic-analysis attack=== There are two methods of traffic-analysis attack, passive and active. In the passive traffic-analysis method, the attacker extracts features from the traffic of a specific flow on one side of the network and looks for those features on the other side of the network. In the active traffic-analysis method, the attacker alters the timings of the packets of a flow according to a specific pattern and looks for that pattern on the other side of the network; therefore, the attacker can link the flows in one side to the other side of the network and break the anonymity of it.{{Failed verification | date = August 2022 | reason = The reference doesn't generally talk about active and passive analysis. It suggests 2 active analyses that match this description, but didn't say this is the only way active analysis can be done like this sentence does. It's questionable that this description is comprehensively right; see relay early traffic confirmation which is an active analysis.}}<ref name=":0">{{cite conference | last1=Soltani | first1=Ramin | last2=Goeckel | first2=Dennis | last3=Towsley | first3=Don | last4=Houmansadr | first4=Amir | title=2017 51st Asilomar Conference on Signals, Systems, and Computers | chapter=Towards provably invisible network flow fingerprints | publisher=IEEE | date = 2017-11-27 | isbn = 978-1-5386-1823-3 | pages = 258–262 | arxiv = 1711.10079 | doi = 10.1109/ACSSC.2017.8335179 | s2cid = 4943955 | chapter-url = https://arxiv.org/pdf/1711.10079.pdf | archiveurl = https://web.archive.org/web/20220505002059/https://arxiv.org/pdf/1711.10079.... | archivedate = 2022-05-05 | url-status = live}}</ref> It is shown that, although timing noise is added to the packets, there are active traffic analysis methods that are robust against such a noise.{{Verify source | date = August 2022}}<!-- It is not obvious whether the source implies this or not. The source just says that you can vary timings of transmission to encode information in a network with transmission modeled by Poisson process.--><ref name=":0" /> [[Steven Murdoch]] and George Danezis from [[University of Cambridge]] presented an article at the 2005 [[Institute of Electrical and Electronics Engineers|IEEE]] [[Symposium]] on security and privacy on traffic-analysis techniques that allow adversaries with only a partial view of the network to infer which nodes are being used to relay the anonymous streams.<ref name="ieee-low-cost" /> These techniques greatly reduce the anonymity provided by Tor. Murdoch and Danezis have also shown that otherwise unrelated streams can be linked back to the same initiator. This attack, however, fails to reveal the identity of the original user.<ref name="ieee-low-cost" /> Murdoch has been working with and has been funded by Tor since 2006.{{Citation needed|date=April 2022}} ===Tor exit node block=== Operators of Internet sites have the ability to prevent traffic from Tor exit nodes or to offer reduced functionality for Tor users. For example, it is not generally possible to edit [[Wikipedia]] when using Tor or when using an IP address also used by a Tor exit node. The [[BBC]] blocks the IP addresses of all known Tor exit nodes from its [[iPlayer]] service, although non-exit relays and bridges are not blocked.<ref>{{cite web |title=BBC iPlayer Help – Why does BBC iPlayer think I'm outside the UK? |url=https://www.bbc.co.uk/iplayer/help/troubleshooting/tv-games-consoles/in_the_... |url-status=dead |archive-url=https://web.archive.org/web/20171228212137/https://www.bbc.co.uk/iplayer/hel... |archive-date=28 December 2017 |access-date=10 September 2017 |website=BBC |language=en-GB}}</ref> ===Bad apple attack=== In March 2011, researchers with the Rocquencourt [[French Institute for Research in Computer Science and Automation]] (''Institut national de recherche en informatique et en automatique'', INRIA), documented an attack that is capable of revealing the IP addresses of [[BitTorrent]] users on the Tor network. The "bad apple attack" exploits Tor's design and takes advantage of insecure application used to associate the simultaneous use of a secure application with the IP address of the Tor user in question. One method of attack depends on control of an exit node or hijacking tracker responses, while a secondary attack method is based in part on the statistical exploitation of [[distributed hash table]] tracking.<ref name="usenix-bad-apple" /> According to the study:<ref name="usenix-bad-apple" /> The results presented in the bad apple attack research paper are based on an attack launched against the Tor network by the authors of the study. The attack targeted six exit nodes, lasted for twenty-three days, and revealed a total of 10,000 IP addresses of active Tor users. This study is significant because it is the first documented attack designed to target [[Peer-to-peer|P2P]] file-sharing applications on Tor.<ref name="usenix-bad-apple" /> BitTorrent may generate as much as 40% of all traffic on Tor.<ref name="shining-light" /> Furthermore, the bad apple attack is effective against insecure use of any application over Tor, not just BitTorrent.<ref name="usenix-bad-apple" /> ===Some protocols exposing IP addresses=== {{Duplication|date=August 2022|section=yes|dupe=#Bad apple attack}} Researchers from the [[French Institute for Research in Computer Science and Automation]] (INRIA) showed that the Tor dissimulation technique in [[BitTorrent]] can be bypassed by attackers controlling a Tor exit node. The study was conducted by monitoring six exit nodes for a period of twenty-three days. Researches used three [[attack vector]]s:<ref name="manils-compromising" /> ;Inspection of BitTorrent control messages: Tracker announces and extension protocol handshakes may optionally contain a client [[IP address]]. Analysis of collected data revealed that 35% and 33% of messages, respectively, contained addresses of clients.<ref name="manils-compromising" />{{rp|3}} ;Hijacking trackers' responses: Due to lack of encryption or authentication in communication between the tracker and peer, typical [[man-in-the-middle attack]]s allow attackers to determine peer IP addresses and even verify the distribution of content. Such attacks work when Tor is used only for tracker communication.<ref name="manils-compromising" />{{rp|4}} ;Exploiting distributed hash tables (DHT): This attack exploits the fact that [[distributed hash table]] (DHT) connections through Tor are impossible, so an attacker is able to reveal a target's IP address by looking it up in the DHT even if the target uses Tor to connect to other peers.<ref name="manils-compromising" />{{rp|4–5}} With these techniques, researchers were able to identify other streams initiated by users, whose IP addresses were revealed.<ref name="manils-compromising" /> ===Sniper attack=== Jansen ''et al.''., describes a [[DDoS]] attack targeted at the Tor node software, as well as defenses against that attack and its variants. The attack works using a colluding client and server, and filling the queues of the exit node until the node runs out of memory, and hence can serve no other (genuine) clients. By attacking a significant proportion of the exit nodes this way, an attacker can degrade the network and increase the chance of targets using nodes controlled by the attacker.<ref name="andssy-sniper" /> ===Heartbleed bug=== The [[Heartbleed]] [[OpenSSL]] [[Software bug|bug]] disrupted the Tor network for several days in April 2014 while [[private key]]s were renewed. The Tor Project recommended Tor relay operators and onion service operators revoke and generate fresh keys after patching OpenSSL, but noted Tor relays use two sets of keys and Tor's multi-hop design minimizes the impact of exploiting a single relay.<ref name="torproject-openssl-cve" /> Five hundred eighty-six relays later found to be susceptible to the Heartbleed bug were taken offline as a precautionary measure.<ref name="ml-rejecting" /><ref name="torproject-news-20140416" /><ref name="ars-ranks-cut" /><ref name="tp-blacklisting" /> {{Anchor |Relay early attack}}<!-- there are links here; please don't move/remove without fixing the links --> === Relay early traffic confirmation attack === {{Further|CERT Coordination Center#Operation Onymous |Operation Onymous#Tor 0-day exploit}} {{POV section|date=February 2021}} On 30 July 2014, the Tor Project issued the security advisory "relay early traffic confirmation attack" in which the project discovered a group of relays that tried to de-anonymize onion service users and operators.<ref>{{harvp | Dingledine |2014}} "On July 4, 2014 we found a group of relays that we assume were trying to deanonymize users. They appear to have been targeting people who operate or access Tor hidden services."</ref> In summary, the attacking onion service directory node changed the headers of cells being relayed tagging them as "relay" or "relay early" cells differently to encode additional information and sent them back to the requesting user/operator. If the user's/operator's guard/entry node was also part of the attacking relays, the attacking relays might be able to capture the IP address of the user/operator along with the onion service information that the user/operator was requesting. The attacking relays were stable enough to be designated as "suitable as hidden service directory" and "suitable as entry guard"; therefore, both the onion service users and the onion services might have used those relays as guards and hidden service directory nodes.<ref name="relay-early-attack">{{cite web |last=Dingledine |first=Roger |date=30 July 2014 |title=Tor security advisory: "relay early" traffic confirmation attack |url=https://blog.torproject.org/tor-security-advisory-relay-early-traffic-confir... |publisher=The Tor Project |access-date=9 July 2018 |archive-date=24 May 2019 |archive-url=https://web.archive.org/web/20190524031037/https://blog.torproject.org/tor-s... |url-status=live }}</ref> The attacking nodes joined the network early in the year on 30 January and the project removed them on 4 July.<ref name=relay-early-attack /> Although the attack's beginning is unclear, the project implied that between February and July, IP addresses of onion service users and operators might have been exposed.<ref>{{harvp | Dingledine |2014}} "...we assume were trying to deanonymize users. They appear to have been targeting people who operate or access Tor hidden services... users who operated or accessed hidden services from early February through July 4 should assume they were affected... We know the attack looked for users who fetched hidden service descriptors... The attack probably also tried to learn who published hidden service descriptors, which would allow the attackers to learn the location of that hidden service... Hidden service operators should consider changing the location of their hidden service."</ref> The project mentioned the following mitigations besides removing the attacking relays from the network: * patched relay software to prevent relays from relaying cells with "relay early" headers that were not intended.<ref>{{harvp | Dingledine |2014}} "Relays should upgrade to a recent Tor release (0.2.4.23 or 0.2.5.6-alpha), to close the particular protocol vulnerability the attackers used..."</ref> * planned update for users' proxy software so that they could inspect if they received "relay early" cells from the relays (as they are not supposed to),<ref>{{harvp | Dingledine |2014}} "For expert users, the new Tor version warns you in your logs if a relay on your path injects any relay-early cells: look for the phrase 'Received an inbound RELAY_EARLY cell'"</ref> along with the settings to connect to just one guard node instead of selecting randomly from 3 to reduce the probability of connecting to an attacking relay<ref>{{harvp | Dingledine |2014}} "Clients that upgrade (once new Tor Browser releases are ready) will take another step towards limiting the number of entry guards that are in a position to see their traffic, thus reducing the damage from future attacks like this one... 3) Put out a software update that will (once enough clients have upgraded) let us tell clients to move to using one entry guard rather than three, to reduce exposure to relays over time."</ref> * recommended that onion services should consider changing their locations<ref>{{harvp | Dingledine |2014}} "Hidden service operators should consider changing the location of their hidden service."</ref> * reminded users and onion service operators that Tor could not prevent de-anonymization if the attacker controlled or could listen to both ends of the Tor circuit, like in this attack.<ref>{{harvp | Dingledine |2014}} "...but remember that preventing traffic confirmation in general remains an open research problem."</ref> In November 2014 there was speculation in the aftermath of [[Operation Onymous]], resulting in 17 arrests internationally, that a Tor weakness had been exploited. A representative of [[Europol]] was secretive about the method used, saying: "''This is something we want to keep for ourselves. The way we do this, we can't share with the whole world, because we want to do it again and again and again.''"<ref name="Wired-2014-11-07">{{Cite magazine |last=Greenberg |first=Andy |date=7 November 2014 |title=Global Web Crackdown Arrests 17, Seizes Hundreds Of Dark Net Domains |url=https://www.wired.com/2014/11/operation-onymous-dark-web-arrests |magazine=Wired |access-date=9 August 2015 |archive-date=9 August 2015 |archive-url=https://web.archive.org/web/20150809113102/http://www.wired.com/2014/11/oper... |url-status=live }}</ref> A [[BBC]] source cited a "technical breakthrough"<ref name="BBC-2014-11-07">{{Cite news |last=Wakefield |first=Jane |date=7 November 2014 |title=Huge raid to shut down 400-plus dark net sites – |work=BBC News |url=https://www.bbc.co.uk/news/technology-29950946 |access-date=9 August 2015 |archive-date=21 August 2015 |archive-url=https://web.archive.org/web/20150821232538/http://www.bbc.co.uk/news/technol... |url-status=live }}</ref> that allowed tracking physical locations of servers, and the initial number of infiltrated sites led to the exploit speculation. Andrew Lewman—a Tor Project representative—downplayed this possibility, suggesting that execution of more traditional police work was more likely.<ref name="crisis">{{cite web |last=O'Neill |first=Patrick Howell |date=7 November 2014 |title=The truth behind Tor's confidence crisis |website=[[The Daily Dot]] |url=http://www.dailydot.com/politics/tor-crisis-of-confidence/ |access-date=10 November 2014 |archive-url=https://web.archive.org/web/20141110122301/http://www.dailydot.com/politics/... |archive-date=10 November 2014 |url-status=live }}</ref><ref>{{cite web |last=Knight |first=Shawn |date=7 November 2014 |title=Operation Onymous seizes hundreds of darknet sites, 17 arrested globally |url=http://www.techspot.com/news/58751-operation-onymous-seizes-hundreds-darknet... |access-date=8 November 2014 |website=Techspot |archive-date=8 November 2014 |archive-url=https://web.archive.org/web/20141108205443/http://www.techspot.com/news/5875... |url-status=live }}</ref> In November 2015 court documents on the matter<ref name="Motherboard2015">{{cite web |date=11 November 2015 |title=Court Docs Show a University Helped FBI Bust Silk Road 2, Child Porn Suspects |url=http://motherboard.vice.com/read/court-docs-show-a-university-helped-fbi-bus... |access-date=20 November 2015 |website=Motherboard |archive-date=21 November 2015 |archive-url=https://web.archive.org/web/20151121155246/http://motherboard.vice.com/read/... |url-status=live }}</ref> addressed concerns about security research ethics<ref name="tor-blog-FBI">{{cite web |date=11 November 2015 |title=Did the FBI Pay a University to Attack Tor Users? |url=https://blog.torproject.org/blog/did-fbi-pay-university-attack-tor-users |access-date=20 November 2015 |website=torproject.org |archive-date=18 November 2015 |archive-url=https://web.archive.org/web/20151118131446/https://blog.torproject.org/blog/... |url-status=live }}</ref>{{Primary source inline|date=February 2021}} and the right of not being unreasonably searched as guaranteed by the US [[Fourth Amendment to the United States Constitution|Fourth Amendment]].<ref name="net-security-2015">{{cite web |last=Zorz |first=Zeljka |date=12 November 2015 |title=Tor Project claims FBI paid university researchers $1m to unmask Tor users |url=http://www.net-security.org/secworld.php?id=19097 |access-date=20 November 2015 |website=Help Net Security |archive-date=17 November 2015 |archive-url=https://web.archive.org/web/20151117020533/http://www.net-security.org/secwo... |url-status=live }}</ref>{{Unreliable source?|date=February 2021}} Moreover, the documents, along with expert opinions,{{Who|date=February 2021}} may also show the connection between the network attack and the law enforcement operation including: * the search warrant for an administrator of Silkroad 2.0 indicated that from January 2014 until July, the FBI received information from a "university-based research institute" with the information being "reliable IP addresses for Tor and onion services such as SR2" that led to the identification of "at least another seventeen black markets on Tor" and "approximately 78 IP addresses that accessed a vendor [[.onion]] address." One of these IP addresses led to the arrest of the administrator<ref name=Motherboard2015 /> * the chronology and nature of the attack fitted well with the operation<ref name=Motherboard2015 /> * a senior researcher of [[International Computer Science Institute]], part of [[University of California, Berkeley]], said in an interview that the institute which worked with the FBI was "almost certainly" [[Carnegie Mellon University]] (CMU),<ref name=Motherboard2015 /> and this concurred with the Tor Project's assessment<ref name=tor-blog-FBI /> and with an earlier analysis of [[Edward Felten]], a computer security professor at [[Princeton University]], about researchers from CMU's [[CERT/CC]] being involved<ref name="Felton2014">{{cite web |last=Felten|first= Ed|date=31 July 2014 |title=Why were CERT researchers attacking Tor? |publisher=Freedom to Tinker, Center for Information Technology Policy, Princeton University |url=https://freedom-to-tinker.com/blog/felten/why-were-cert-researchers-attackin... |access-date=9 July 2018 |archive-url=https://web.archive.org/web/20160905235550/https://freedom-to-tinker.com/blo... |archive-date=5 September 2016 |url-status=live }}</ref> In his analysis published on 31 July, besides raising ethical issues, Felten also questioned the fulfillment of CERT/CC's purposes which were to prevent attacks, inform the implementers of vulnerabilities, and eventually inform the public. Because in this case, CERT/CC's staff did the opposite which was to carry out a large-scale long-lasting attack, withhold vulnerability information from the implementers, and withhold the same information from the public.<ref name=Felton2014 />{{Unreliable source?|date=February 2021}} CERT/CC is a non-profit, computer security research organization [[Government spending|publicly funded]] through the [[US federal government]].{{Citation needed|date=February 2021}}<ref>{{Cite journal|last=Madnick |first=Stuart |author2=Xitong Li |author3=Nazli Choucri|date=2009|title=Experiences and challenges with using CERT data to analyze international cyber security|journal=MIT Sloan Research Paper}}</ref> ===Mouse fingerprinting=== In March 2016, a security researcher based in [[Barcelona]] demonstrated laboratory techniques using time measurement via [[JavaScript]] at the 1-[[millisecond]] level<ref name="Researcher finds new methods of deanonymizing Tor users">{{cite web |last=Cimpanu |first=Catalin |date=10 March 2016 |title=Tor Users Can Be Tracked Based on Their Mouse Movements |url=http://news.softpedia.com/news/tor-users-can-be-tracked-based-on-their-mouse... |access-date=11 March 2016 |website=Softpedia |archive-date=11 March 2016 |archive-url=https://web.archive.org/web/20160311122218/http://news.softpedia.com/news/to... |url-status=live }}</ref> which could potentially identify and correlate a user's unique [[computer mouse|mouse]] movements, provided the user has visited the same "fingerprinting" website with both the Tor browser and a regular browser.{{citation needed|date=November 2020}} This [[proof of concept]] exploits the "time measurement via JavaScript" issue, which had been an open ticket on the Tor Project for ten months.<ref name="Open Ticket for Ten Months">{{cite web |last=Anonymous |date=10 March 2016 |title=Tor Users Can Be Tracked Based On Their Mouse Movements |url=http://news.slashdot.org/story/16/03/11/0045203/tor-users-can-be-tracked-bas... |access-date=11 March 2016 |website=Slashdot |archive-date=12 March 2016 |archive-url=https://web.archive.org/web/20160312071945/http://news.slashdot.org/story/16... |url-status=live }}</ref> ===Circuit fingerprinting attack=== In 2015, the administrators of [[Agora (online marketplace)|Agora]], a [[darknet market]], announced they were taking the site offline in response to a recently discovered security vulnerability in Tor. They did not say what the vulnerability was, but Wired speculated it was the "Circuit Fingerprinting Attack" presented at the Usenix security conference.<ref>{{Cite magazine |last=Greenberg |first=Andy |date=26 August 2015 |title=Agora, the Dark Web's Biggest Drug Market, Is Going Offline |url=https://www.wired.com/2015/08/agora-dark-webs-biggest-drug-market-going-offl... |magazine=Wired |access-date=13 September 2016 |archive-date=15 August 2016 |archive-url=https://web.archive.org/web/20160815105345/https://www.wired.com/2015/08/ago... |url-status=live }}</ref><ref>{{cite web |author1=Albert Kwon |author2=Mashael AlSabah |author3=David Lazar |author4=Marc Dacier |author5=Srinivas Devadas |date=August 2015 |title=Circuit Fingerprinting Attacks: Passive Deanonymization of Tor Hidden Services |url=https://www.usenix.org/system/files/conference/usenixsecurity15/sec15-paper-... |access-date=14 July 2016 |archive-date=9 April 2016 |archive-url=https://web.archive.org/web/20160409103456/https://www.usenix.org/system/fil... |url-status=live }}</ref> ===Volume information=== A study showed "anonymization solutions protect only partially against target selection that may lead to efficient surveillance" as they typically "do not hide the volume information necessary to do target selection".<ref>{{cite web |title=The Economics of Mass Surveillance and the Questionable Value of Anonymous Communications |url=http://www.econinfosec.org/archive/weis2006/docs/36.pdf|first1=George|last1=Danezis1|first2=Bettina|last2=Wittneben|via=ecoinfosec.org|access-date=27 April 2022 |archive-date=25 October 2016 |archive-url=https://web.archive.org/web/20161025002654/http://www.econinfosec.org/archiv... |url-status=live }}</ref> ==Implementations== {{See also|The Tor Project#Tools|Guardian Project (software)#Projects}} The main implementation of Tor is written primarily in [[C (programming language)|C]]<ref name="tor-gitlab-repoanalytics" /> === Tor Browser === <!-- [[Portable Tor]] and [[Tor Browser Bundle]] redirect to this section --> {{Infobox software | name = Tor Browser | screenshot = File:Tor-9.png | caption = Tor Browser on [[Ubuntu]] showing its start page – about:tor | developer = Tor Project | ver layout = stacked | latest release version = {{Multiple releases |branch1=Android |version1={{wikidata|property|preferred|references|edit|Q15397253|P348|P400=Q94|P548=Q2804309}} |date1={{wikidata|qualifier|preferred|single|Q15397253|P348|P400=Q94|P548=Q2804309|P577}} |branch2=Linux |version2={{wikidata|property|preferred|references|edit|Q15397253|P348|P400=Q388|P548=Q2804309}} |date2={{wikidata|qualifier|preferred|single|Q15397253|P348|P400=Q388|P548=Q2804309|P577}} |branch3=macOS |version3={{wikidata|property|preferred|references|edit|Q15397253|P348|P400=Q14116|P548=Q2804309}} |date3={{wikidata|qualifier|preferred|single|Q15397253|P348|P400=Q14116|P548=Q2804309|P577}} |branch4=Windows |version4={{wikidata|property|preferred|references|edit|Q15397253|P348|P400=Q1406|P548=Q2804309}} |date4={{wikidata|qualifier|preferred|single|Q15397253|P348|P400=Q1406|P548=Q2804309|P577}} }} | latest preview version = {{Multiple releases |branch1=Android |version1={{wikidata|property|preferred|references|edit|Q15397253|P348|P400=Q94|P548=Q51930650}} |date1={{wikidata|qualifier|preferred|single|Q15397253|P348|P400=Q94|P548=Q51930650|P577}} |branch2=Linux |version2={{wikidata|property|preferred|references|edit|Q15397253|P348|P400=Q388|P548=Q51930650}} |date2={{wikidata|qualifier|preferred|single|Q15397253|P348|P400=Q388|P548=Q51930650|P577}} |branch3=macOS |version3={{wikidata|property|preferred|references|edit|Q15397253|P348|P400=Q14116|P548=Q51930650}} |date3={{wikidata|qualifier|preferred|single|Q15397253|P348|P400=Q14116|P548=Q51930650|P577}} |branch4=Windows |version4={{wikidata|property|preferred|references|edit|Q15397253|P348|P400=Q1406|P548=Q51930650}} |date4={{wikidata|qualifier|preferred|single|Q15397253|P348|P400=Q1406|P548=Q51930650|P577}} }} | repo = {{URL|https://gitweb.torproject.org/tor-browser.git/}} | engine = [[Gecko (software)|Gecko]] | operating system = {{flatlist| * [[Windows XP]] and later * [[Unix-like]] (inc. [[macOS]]) * [[Android (operating system)|Android]]}} | size = {{Nowrap|65–90 MB}} | language = 36 languages<ref>{{cite web|url=https://www.torproject.org/download/languages/|title=Download Tor Browser in your language|publisher=[[The Tor Project, Inc.]]|access-date=7 July 2021}}</ref> | genre = [[Onion routing]], [[anonymity]], [[web browser]], [[feed reader]] | license = [[Mozilla Public License]]<ref name="license">{{cite web|title=Tor Project: FAQ |url=https://torproject.org/docs/faq.html.en |website=torproject.org |access-date=31 October 2019 |archive-date=24 March 2019 |archive-url=https://web.archive.org/web/20190324153623/https://www.torproject.org/docs/f... |url-status=live}}</ref> | website = {{URL|torproject.org}} }} [[File:Tor Browser icon.svg|90px|thumb|Tor Browser-Logo|left]] The Tor Browser<ref name="tbb">{{cite web |date=23 June 2014 |title=Tor Browser Bundle |url=https://www.torproject.org/projects/torbrowser.html.en |archive-url=https://web.archive.org/web/20140623203436/https://www.torproject.org/projec... |archive-date=23 June 2014 |access-date=21 May 2017 |website=Tor Project}}</ref> is the flagship product of the Tor Project. It was created as the Tor Browser Bundle by [[Steven J. Murdoch]]<ref name="torproject-corepeople" /> and announced in January 2008.<ref name="tbbannounce">{{Cite mailing list |last=Murdoch |first=Steven J. |author-link=Steven J. Murdoch |date=30 January 2008 |title=New Tor distribution for testing: Tor Browser Bundle |mailing-list=tor-talk |url=https://lists.torproject.org/pipermail/tor-talk/2008-January/007837.html |access-date=13 January 2020 |archive-date=5 March 2020 |archive-url=https://web.archive.org/web/20200305015731/https://lists.torproject.org/pipe... |url-status=live }}</ref> The Tor Browser consists of a modified Mozilla [[Firefox]] ESR web browser, the TorButton, TorLauncher, [[NoScript]] and the Tor proxy.<ref name="tbb-design-document" /><ref name="wu8-ubuntu-ppa" /> Users can run the Tor Browser from [[removable media]]. It can operate under [[Microsoft Windows]], [[macOS]], [[Android (operating system)|Android]] and [[Linux]].<ref name="lj-portable" /> The default [[search engine]] is [[DuckDuckGo]] (until version 4.5, [[Startpage.com]] was its default). The Tor Browser automatically starts Tor background processes and routes traffic through the Tor network. Upon termination of a session the browser deletes privacy-sensitive data such as HTTP cookies and the browsing history.<ref name="wu8-ubuntu-ppa" /> This is effective in reducing [[web tracking]] and [[canvas fingerprinting]], and it also helps to prevent creation of a [[filter bubble]].{{citation needed|date=April 2022}} To allow download from places where accessing the Tor Project URL may be risky or blocked, a [[GitHub]] repository is maintained with links for releases hosted in other domains.<ref>{{cite web |date=23 September 2020 |title=This repository contains TorBrowser Releases. |website=[[GitHub]] |url=https://github.com/TheTorProject/gettorbrowser |access-date=23 September 2020 |archive-date=23 September 2020 |archive-url=https://web.archive.org/web/20200923155534/https://github.com/TheTorProject/... |url-status=live }}</ref> {{Anchor|EgotisticalGiraffe}} ==== Firefox/Tor browser attack ==== In 2011, the [[Law enforcement in the Netherlands|Dutch authority]] investigating [[child pornography]] discovered the IP address of a Tor onion service site called "Pedoboard" from an unprotected administrator's account and gave it to the [[FBI]], who traced it to Aaron McGrath. After a year of surveillance, the FBI launched "[[Operation Torpedo]]" which resulted in McGrath's arrest and allowed them to install their [[Network Investigative Technique]] (NIT) malware on the servers for retrieving information from the users of the three onion service sites that McGrath controlled.<ref>{{Cite magazine |last=Poulsen |first=Kevin |date=8 May 2014 |title=Visit the Wrong Website, and the FBI Could End Up in Your Computer |url=https://www.wired.com/2014/08/operation_torpedo/ |magazine=[[Wired (magazine)|Wired]] |access-date=12 March 2017 |archive-date=11 January 2018 |archive-url=https://web.archive.org/web/20180111024650/https://www.wired.com/2014/08/ope... |url-status=live }}</ref> The technique, exploiting a Firefox/Tor browser's vulnerability that had been patched and targeting users that had not updated, had a [[Adobe Flash|Flash]] application pinging a user's IP address directly back to an FBI server,<ref>{{cite web |date=16 July 2015 |title=Feds bust through huge Tor-hidden child porn site using questionable malware |url=https://arstechnica.com/tech-policy/2015/07/feds-bust-through-huge-tor-hidde... |website=Ars Technica |access-date=26 July 2018 |archive-date=24 March 2020 |archive-url=https://web.archive.org/web/20200324213851/https://arstechnica.com/tech-poli... |url-status=live }}</ref><ref>{{cite web |title=FBI Tor busting 227 1 |url=https://www.documentcloud.org/documents/2124281-fbi-tor-busting-227-1.html |access-date=26 July 2018 |archive-date=2 July 2018 |archive-url=https://web.archive.org/web/20180702204642/https://www.documentcloud.org/doc... |url-status=live }}</ref><ref>{{Cite journal |last1=Miller |first1=Matthew |last2=Stroschein |first2=Joshua |last3=Podhradsky |first3=Ashley |date=25 May 2016 |title=Reverse Engineering a NIT That Unmasks Tor Users |url=https://commons.erau.edu/adfsl/2016/wednesday/10/ |journal=Annual ADFSL Conference on Digital Forensics, Security and Law |access-date=26 July 2018 |archive-date=2 July 2018 |archive-url=https://web.archive.org/web/20180702204544/https://commons.erau.edu/adfsl/20... |url-status=live }}</ref><ref>{{Cite magazine |date=16 December 2014 |title=The FBI Used the Web's Favorite Hacking Tool to Unmask Tor Users |url=https://www.wired.com/2014/12/fbi-metasploit-tor/ |magazine=Wired |access-date=26 July 2018 |archive-date=22 February 2019 |archive-url=https://web.archive.org/web/20190222011924/https://www.wired.com/2014/12/fbi... |url-status=live }}</ref> and resulted in revealing at least 25 US users as well as numerous users from other countries.<ref name="WiredDeFoggi">{{Cite magazine |date=27 August 2014 |title=Federal Cybersecurity Director Found Guilty on Child Porn Charges |url=https://www.wired.com/2014/08/federal-cybersecurity-director-guilty-child-po... |magazine=Wired |access-date=26 July 2018 |archive-date=23 February 2019 |archive-url=https://web.archive.org/web/20190223085543/https://www.wired.com/2014/08/fed... |url-status=live }}</ref> McGrath was sentenced to 20 years in prison in early 2014, with at least 18 other users including a former Acting [[United States Department of Health and Human Services|HHS]] Cyber Security Director being sentenced in subsequent cases.<ref>{{cite web |date=5 January 2015 |title=Former Acting HHS Cyber Security Director Sentenced to 25 Years in Prison for Engaging in Child Pornography Enterprise |url=https://www.justice.gov/opa/pr/former-acting-hhs-cyber-security-director-sen... |url-status=live |archive-url=https://web.archive.org/web/20180702233127/https://www.justice.gov/opa/pr/fo... |archive-date=2 July 2018 |publisher=US Department of Justice}}</ref><ref>{{cite web |date=17 December 2015 |title=New York Man Sentenced to Six Years in Prison for Receiving and Accessing Child Pornography |url=https://www.justice.gov/opa/pr/new-york-man-sentenced-six-years-prison-recei... |url-status=live |archive-url=https://web.archive.org/web/20180705062657/https://www.justice.gov/opa/pr/ne... |archive-date=5 July 2018 |publisher=US Department of Justice}}</ref> In August 2013 it was discovered<ref>{{Cite magazine|last=Poulsen|first=Kevin|date=2013-08-05|title=Feds Are Suspects in New Malware That Attacks Tor Anonymity|magazine=Wired|url=https://www.wired.com/2013/08/freedom-hosting/|access-date=12 March 2017|archive-date=29 April 2014|archive-url=https://web.archive.org/web/20140429202100/http://www.wired.com/2013/08/freedom-hosting/|url-status=live}}</ref><ref>{{cite web|last=Krebs|first=Brian|date=2013-08-13|title=Firefox Zero-Day Used in Child Porn Hunt?|url=https://krebsonsecurity.com/2013/08/firefox-zero-day-used-in-child-porn-hunt/|access-date=2020-12-26|website=Krebs on Security|archive-date=13 December 2020|archive-url=https://web.archive.org/web/20201213180903/https://krebsonsecurity.com/2013/08/firefox-zero-day-used-in-child-porn-hunt/|url-status=live}}</ref> that the [[Firefox]] browsers in many older versions of the Tor Browser Bundle were vulnerable to a JavaScript-deployed [[shellcode]] attack, as NoScript was not enabled by default.<ref name="guardian-peeling" /> Attackers used this vulnerability to extract users' MAC and IP addresses and Windows computer names.<ref name="iw-info-stealing" /><ref name="wired-feds-are-suspects" /><ref name="ghowen-fby-analysis" /> News reports linked this to an [[Federal Bureau of Investigation]] (FBI) operation targeting [[Freedom Hosting]]'s owner, Eric Eoin Marques, who was arrested on a provisional extradition warrant issued by a United States' court on 29 July.<ref>{{Cite news|last=O'Faolain|first=Aodhan|date=2013-08-08|title=Man sought in US on child porn charges further remanded in custody|newspaper=The Irish Times|url=https://www.irishtimes.com/news/ireland/irish-news/man-sought-in-us-on-child-porn-charges-further-remanded-in-custody-1.1488624|access-date=2020-12-26|archive-date=9 August 2013|archive-url=https://web.archive.org/web/20130809222019/http://www.irishtimes.com/news/ireland/irish-news/man-sought-in-us-on-child-porn-charges-further-remanded-in-custody-1.1488624|url-status=live}}</ref> The FBI extradited Marques from Ireland to the state of Maryland on 4 charges: distributing; conspiring to distribute; and advertising [[child pornography]], as well as aiding and abetting advertising of child pornography.<ref>[https://www.theguardian.com/us-news/2021/sep/16/man-behind-worlds-biggest-so... Man behind world's biggest source of child abuse imagery is jailed for 27 years], the guardian.com, 2021/09/16</ref> The warrant alleged that Marques was "the largest facilitator of child porn on the planet".<ref name="mirror-marques" /><ref name="torproject-old-vulnerable" />{{qn|date=December 2016}} The FBI acknowledged the attack in a 12 September 2013 court filing in [[Dublin]];<ref name="wired-fbi-controlled" /> further technical details from a training presentation leaked by [[Edward Snowden]] revealed the code name for the exploit as "EgotisticalGiraffe".<ref name="guardian-how-nsa" /> === Tor Messenger === {{Infobox software | name = Tor Messenger | logo = [[File:Tor-messenger.svg|128px]] | logo alt = | screenshot = <!-- Image name is enough --> | caption = | author = | developer = The Tor Project | released = {{Start date and age|2015|10|29|df=yes}}<ref name="auto">{{cite web |last=Singh |first=Sukhbir |date=29 October 2015 |title=Tor Messenger Beta: Chat over Tor, Easily |url=https://blog.torproject.org/blog/tor-messenger-beta-chat-over-tor-easily |access-date=31 October 2015 |website=The Tor Blog |publisher=The Tor Project |archive-date=30 October 2015 |archive-url=https://web.archive.org/web/20151030223028/https://blog.torproject.org/blog/... |url-status=live }}</ref> | discontinued = yes <!-- NOTE: While 0.5.0-beta-1 is a preview release, it is specified in "latest release version" so that it is correctly displayed as the final release. -->| latest release version = 0.5.0-beta-1 | latest release date = {{Start date and age|2017|09|28|df=yes}}<ref>{{cite web |last=Singh |first=Sukhbir |date=28 September 2017 |title=Tor Messenger 0.5.0b1 is released |url=https://blog.torproject.org/tor-messenger-050b1-released |access-date=6 October 2017 |website=sukhbir's blog |publisher=The Tor Project |archive-date=6 October 2017 |archive-url=https://web.archive.org/web/20171006112837/https://blog.torproject.org/tor-m... |url-status=live }}</ref><ref name=sunset-tormes>{{cite web |last=Singh |first=Sukhbir |date=2 April 2018 |title=Sunsetting Tor Messenger |url=https://blog.torproject.org/sunsetting-tor-messenger |access-date=9 April 2020 |archive-date=2 April 2020 |archive-url=https://web.archive.org/web/20200402233906/https://blog.torproject.org/sunse... |url-status=live }}</ref> | repo = https://gitweb.torproject.org/tor-messenger-build.git | programming language = [[C/C++]], [[JavaScript]], [[Cascading Style Sheets|CSS]], [[XUL]] | operating system = {{flatlist| * [[Windows XP]] and later * [[Unix-like]] (inc. [[macOS]])}} | size = | language = English | genre = | license = | website = {{URL|https://trac.torproject.org/projects/tor/wiki/doc/TorMessenger}} }} On 29 October 2015, the Tor Project released Tor Messenger Beta, an instant messaging program based on [[Instantbird]] with Tor and [[Off-the-Record Messaging|OTR]] built in and used by default.<ref name="auto" /> Like [[Pidgin (software)|Pidgin]] and [[Adium]], Tor Messenger supports multiple different instant messaging protocols; however, it accomplishes this without relying on ''libpurple'', implementing all chat protocols in the memory-safe language JavaScript instead.<ref>{{cite web |date=13 July 2015 |title=Tor Messenger Design Document |url=https://trac.torproject.org/projects/tor/wiki/doc/TorMessenger/DesignDoc |access-date=22 November 2015 |website=The Tor Project |archive-date=22 November 2015 |archive-url=https://web.archive.org/web/20151122170840/https://trac.torproject.org/proje... |url-status=live }}</ref><ref>{{cite web |title=Sunsetting Tor Messenger {{!}} Tor Project |url=https://blog.torproject.org/sunsetting-tor-messenger/ |access-date=2022-05-07 |website=blog.torproject.org}}</ref> According to Lucian Armasu of Toms Hardware, in April 2018, the Tor Project shut down the Tor Messenger project for three reasons: the developers of "Instabird" {{sic}} discontinued support for their own software, limited resources and known metadata problems.<ref>{{cite web |last=Aemasu |first=Lucian |date=3 April 2018 |title=Tor Project Shuts Down Development Of Tor Messenger |url=http://www.tomshardware.com/news/tor-project-ends-tor-messenger,36811.html |access-date=3 April 2018 |website=Tom's Hardware |language=en}}</ref> The Tor Messenger developers explained that overcoming any vulnerabilities discovered in the future would be impossible due to the project relying on outdated software dependencies.<ref>{{cite web |last=Sharwood |first=Simon |date=3 April 2018 |title=Tor 'sunsets' secure Messenger that never exited beta |url=https://www.theregister.co.uk/2018/04/03/tor_messenger_sunset/ |url-status=live |archive-url=https://web.archive.org/web/20180715115016/https://www.theregister.co.uk/201... |archive-date=15 July 2018 |access-date=2 October 2019 |website=The Register |language=en}}</ref> ===Tor Phone=== {{See also|Tor Phone}} In 2016, Tor developer Mike Perry announced a prototype tor-enabled smartphone bases on [[CopperheadOS]].<ref>{{Cite web |last=Staff |first=Ars |date=2016-11-22 |title=Tor phone is antidote to Google "hostility" over Android, says developer |url=https://arstechnica.com/information-technology/2016/11/tor-phone-prototype-g... |access-date=2022-08-13 |website=Ars Technica |language=en-us}}</ref> It was meant as a direction for tor on mobile. The project was called 'Mission Improbable'. Copperhead's then lead developer Daniel Micah welcomed the prototype. ===Third-party applications=== The [[Vuze]] (formerly Azureus) [[BitTorrent]] client,<ref name="vuze-tor" /> [[Bitmessage]] anonymous messaging system,<ref name="bitmessage-faq" /> and [[TorChat]] instant messenger include Tor support. OnionShare allows users to share files using Tor.<ref name="Hassan2016">{{cite book |last1=Hassan |first1=Nihad |last2=Hijazi |first2=Rami |title=Data Hiding Techniques in Windows OS: A Practical Approach to Investigation and Defense |year=2016 |publisher=Syngress |isbn=978-0-12-804496-4 |page=184 |url=https://books.google.com/books?id=sy2lCgAAQBAJ&pg=PA184}}</ref> [[Guardian Project (software)|The Guardian Project]] is actively developing a free and open-source suite of applications and firmware for the [[Android (operating system)|Android operating system]] to improve the security of mobile communications.<ref name="guardianproject-about" /> The applications include the [[ChatSecure]] instant messaging client,<ref name="guardianproject-chatsecure" /> [[Orbot]] Tor implementation<ref name="guardianproject-orbot" /> (also available for iOS),<ref>{{Citation |title=Orbot iOS |date=2022-08-25 |url=https://github.com/guardianproject/orbot-ios |publisher=Guardian Project |access-date=2022-08-25}}</ref> Orweb (discontinued) privacy-enhanced mobile browser,<ref name="guardianproject-orweb" /><ref name="n8fr8">{{cite web |last=n8fr8 |date=30 June 2015 |title=Orfox: Aspiring to bring Tor Browser to Android |url=https://guardianproject.info/2015/06/30/orfox-aspiring-to-bring-tor-browser-... |access-date=17 August 2015 |website=guardianproject.info |quote=Our plan is to actively encourage users to move from Orweb to Orfox, and stop active development of Orweb, even removing to from the Google Play Store. |archive-date=13 September 2015 |archive-url=https://web.archive.org/web/20150913130030/https://guardianproject.info/2015... |url-status=live }}</ref> Orfox, the mobile counterpart of the Tor Browser, ProxyMob [[Firefox add-on]],<ref name="guardianproject-proxymob" /> and ObscuraCam.<ref name="guardianproject-obscuracam" /> [[Onion Browser]]<ref>[https://mtigas/OnionBrowser/blob/2.X/LICENSE Endless / Onion Browser License (OBL)]</ref> is open-source, privacy-enhancing web browser for [[iOS]], which uses Tor.<ref>{{cite web|title=Tor at the Heart: Onion Browser (and more iOS Tor) |publisher=The Tor Blog |url=https://blog.torproject.org/blog/tor-heart-onion-browser-and-more-ios-tor|format=|access-date=|last=|date=|year=|language=|pages=}}</ref> It is available in the iOS [[App Store]],<ref>[https://apps.apple.com/en/app/onion-browser/id519296448 Onion Browser on the App Store]</ref> and source code is available on [[GitHub]].<ref name="github-OnionBro">{{cite web|title=OnionBrowser/OnionBrowser|periodical=GitHub|url=https://github.com/OnionBrowser/OnionBrowser|format=|access-date=|last=|date=2021-06-30|language=en|pages=}}</ref> [[Brave (web browser)|Brave]] added support for [[Tor (anonymity network)|Tor]] in its desktop browser's [[private browsing|private-browsing]] mode.<ref>{{cite web|last=Shankland|first=Stephen|title=Brave advances browser privacy with Tor-powered tabs|url=https://www.cnet.com/news/brave-advances-browser-privacy-with-tor-powered-tabs/|publisher=CNET|date=28 June 2018|access-date=27 September 2018|archive-date=27 September 2018|archive-url=https://web.archive.org/web/20180927204204/https://www.cnet.com/news/brave-advances-browser-privacy-with-tor-powered-tabs/|url-status=live}}</ref> Users can switch to Tor-enabled browsing by clicking on the hamburger menu on the top right corner of the browser.<ref>{{cite web|last=Brave|date=2020-10-05|title=Brave.com now has its own Tor Onion Service, providing more users with secure access to Brave|url=https://brave.com/new-onion-service/|access-date=2021-01-22|website=Brave Browser|archive-date=6 October 2020|archive-url=https://web.archive.org/web/20201006004823/https://brave.com/new-onion-service/|url-status=live}}</ref> <gallery> File:Orbot-logo.svg|Orbot logo File:Onion Browser Icon 2017.png|Onion Browser logo File:Onion Browser on iPad.png|Onion Browser on [[iPad]] File:Onion Browser 2.8.1 on iPhone.png|Onion Browser 2.8.1 on [[iPhone]] </gallery> ===Security-focused operating systems=== Several [[security-focused operating system]]s make or made extensive use of Tor. These include [[Hardened Linux From Scratch]], [[Incognito (operating system)|Incognito]], [[Security-focused operating system#Liberté Linux|Liberté Linux]], [[Qubes OS]], [[Subgraph (operating system)|Subgraph]], [[Tails (operating system)|Tails]], Tor-ramdisk, and [[Whonix]].<ref name="xakep-whole-hog" /> == Reception, impact, and legislation == [[File:TorPluggable transports-animation.webm|thumb|A very brief animated primer on Tor pluggable transports,<ref name="Tor Project: Pluggable Transports">{{cite web |title=Tor Project: Pluggable Transports |url=https://www.torproject.org/docs/pluggable-transports.html.en |access-date=5 August 2016 |website=torproject.org |archive-date=13 August 2016 |archive-url=https://web.archive.org/web/20160813004757/https://www.torproject.org/docs/p... |url-status=live }}</ref> a method of accessing the anonymity network.]] Tor has been praised for providing privacy and anonymity to vulnerable Internet users such as political activists fearing surveillance and arrest, ordinary web users seeking to circumvent censorship, and people who have been threatened with violence or abuse by stalkers.<ref>{{Cite news |last=Brandom |first=Russell |date=9 May 2014 |title=Domestic violence survivors turn to Tor to escape abusers |work=The Verge |url=https://www.theverge.com/2014/5/9/5699600/domestic-violence-survivors-turn-t... |access-date=30 August 2014 |archive-date=2 September 2014 |archive-url=https://web.archive.org/web/20140902093440/http://www.theverge.com/2014/5/9/... |url-status=live }}</ref><ref>{{Cite news |last=Gurnow |first=Michael |date=1 July 2014 |title=Seated Between Pablo Escobar and Mahatma Gandhi: The Sticky Ethics of Anonymity Networks |work=Dissident Voice |url=http://dissidentvoice.org/2013/06/seated-between-pablo-escobar-and-mahatma-g... |access-date=17 July 2014 |archive-date=6 October 2014 |archive-url=https://web.archive.org/web/20141006101844/http://dissidentvoice.org/2013/06... |url-status=live }}</ref> The U.S. National Security Agency (NSA) has called Tor "the king of high-secure, low-latency Internet anonymity",<ref name="guardian-nsa-target" /> and ''[[BusinessWeek]]'' magazine has described it as "perhaps the most effective means of defeating the online surveillance efforts of intelligence agencies around the world".<ref name=bw-tor-vs /> Other media have described Tor as "a sophisticated privacy tool",<ref>{{Cite magazine |last=Zetter |first=Kim |date=1 June 2010 |title=WikiLeaks Was Launched With Documents Intercepted From Tor |magazine=Wired |url=https://www.wired.com/2010/06/wikileaks-documents/ |access-date=30 August 2014 |archive-date=12 August 2014 |archive-url=https://web.archive.org/web/20140812114104/http://www.wired.com/2010/06/wiki... |url-status=live }}</ref> "easy to use"<ref>{{Cite news |last=Lee |first=Timothy B. |date=10 June 2013 |title=Five ways to stop the NSA from spying on you |newspaper=[[The Washington Post]] |url=https://www.washingtonpost.com/blogs/wonkblog/wp/2013/06/10/five-ways-to-sto... |access-date=30 August 2014 |archive-date=4 October 2014 |archive-url=https://web.archive.org/web/20141004072624/http://www.washingtonpost.com/blo... |url-status=live }}</ref> and "so secure that even the world's most sophisticated electronic spies haven't figured out how to crack it".<ref name="thecable">{{Cite news |last1=Harris |first1=Shane |last2=Hudson |first2=John |date=4 October 2014 |title=Not Even the NSA Can Crack the State Department's Favorite Anonymous Service |work=[[Foreign Policy]] |url=http://thecable.foreignpolicy.com/posts/2013/10/04/not_even_the_nsa_can_crac... |access-date=30 August 2014 |archive-date=20 July 2014 |archive-url=https://web.archive.org/web/20140720045913/http://thecable.foreignpolicy.com... |url-status=live }}</ref> Advocates for Tor say it supports [[freedom of expression]], including in countries where the Internet is censored, by protecting the privacy and anonymity of users. The mathematical underpinnings of Tor lead it to be characterized as acting "like a piece of [[infrastructure]], and governments naturally fall into paying for infrastructure they want to use".<ref>{{cite web |last=Norton |first=Quinn |date=9 December 2014 |title=Clearing the air around Tor |url=http://pando.com/2014/12/09/clearing-the-air-around-tor/ |website=[[PandoDaily]] |access-date=10 December 2014 |archive-date=25 May 2019 |archive-url=https://web.archive.org/web/20190525115617/https://pando.com/2014/12/09/clea... |url-status=live }}</ref> The project was originally developed on behalf of the U.S. intelligence community and continues to receive U.S. government funding, and has been criticized as "more resembl[ing] a spook project than a tool designed by a culture that values accountability or transparency".<ref name="pando">{{Cite news|last=Levine|first=Yasha|date=16 July 2014|title=Almost everyone involved in developing Tor was (or is) funded by the US government|work=Pando Daily|url=http://pando.com/2014/07/16/tor-spooks/|url-status=live|access-date=21 April 2016|archive-url=https://web.archive.org/web/20160411185901/https://pando.com/2014/07/16/tor-spooks/|archive-date=11 April 2016}}</ref> {{as of|2012}}, 80% of The Tor Project's $2M annual budget came from the [[United States government]], with the [[U.S. State Department]], the [[Broadcasting Board of Governors]], and the [[National Science Foundation]] as major contributors,<ref name="boston-free-speech-tech" /> aiming "to aid democracy advocates in authoritarian states".<ref name="NDR">{{Cite news|date=3 July 2014|title=NSA targets the privacy-conscious|work=Panorama|publisher=Norddeutscher Rundfunk|url=http://daserste.ndr.de/panorama/aktuell/nsa230_page-1.html|url-status=live|access-date=4 July 2014|archive-url=https://web.archive.org/web/20140703215350/http://daserste.ndr.de/panorama/aktuell/nsa230_page-1.html|archive-date=3 July 2014|vauthors=Appelbaum J, Gibson A, Goetz J, Kabisch V, Kampf L, Ryge L}}</ref> Other public sources of funding include [[DARPA]], the [[United States Naval Research Laboratory|U.S. Naval Research Laboratory]], and the [[Government of Sweden]].<ref name="torproject-sponsors" /><ref name="wsj-anonymous-contraversial" /> Some have proposed that the government values Tor's commitment to free speech, and uses the darknet to gather intelligence.<ref>Moore, Daniel; Rid, Thomas. "Cryptopolitik and the Darknet". Survival. Feb2016, Vol. 58 Issue 1, p7-38. 32p.</ref>{{Request quotation | date=July 2018}} Tor also receives funding from [[Non-governmental organization|NGOs]] including [[Human Rights Watch]], and private sponsors including [[Reddit]] and [[Google]].<ref>Inc., The Tor Project,. "Tor: Sponsors". www.torproject.org. Retrieved 28 October 2016.</ref> Dingledine said that the [[United States Department of Defense]] funds are more similar to a [[research grant]] than a [[procurement|procurement contract]]. Tor executive director Andrew Lewman said that even though it accepts funds from the U.S. federal government, the Tor service did not collaborate with the NSA to reveal identities of users.<ref name="wp-feds-pay" /> Critics say that Tor is not as secure as it claims,<ref>{{Cite news |date=2 September 2013 |title=Tor is Not as Safe as You May Think |work=Infosecurity magazine |url=http://www.infosecurity-magazine.com/news/tor-is-not-as-safe-as-you-may-thin... |access-date=30 August 2014 |archive-date=27 August 2014 |archive-url=https://web.archive.org/web/20140827203552/http://www.infosecurity-magazine.... |url-status=live }}</ref> pointing to U.S. law enforcement's investigations and shutdowns of Tor-using sites such as web-hosting company [[Freedom Hosting]] and online marketplace [[Silk Road (marketplace)|Silk Road]].<ref name="pando" /> In October 2013, after analyzing documents leaked by Edward Snowden, ''The Guardian'' reported that the NSA had repeatedly tried to crack Tor and had failed to break its core security, although it had had some success attacking the computers of individual Tor users.<ref name="guardian-nsa-target" /> ''The Guardian'' also published a 2012 NSA classified slide deck, entitled "Tor Stinks", which said: "We will never be able to de-anonymize all Tor users all the time", but "with manual analysis we can de-anonymize a very small fraction of Tor users".<ref>{{Cite news |date=4 October 2014 |title='Tor Stinks' presentation – read the full document |work=The Guardian |url=https://www.theguardian.com/world/interactive/2013/oct/04/tor-stinks-nsa-pre... |access-date=30 August 2014 |archive-date=29 August 2014 |archive-url=https://web.archive.org/web/20140829193451/http://www.theguardian.com/world/... |url-status=live }}</ref> When Tor users are arrested, it is typically due to human error, not to the core technology being hacked or cracked.<ref>{{cite web |last=O'Neill |first=Patrick Howell |date=2 October 2014 |title=The real chink in Tor's armor |url=http://www.dailydot.com/crime/silk-road-tor-arrests/ |website=The Daily Dot |access-date=3 October 2014 |archive-date=25 May 2019 |archive-url=https://web.archive.org/web/20190525124144/https://www.dailydot.com/crime/si... |url-status=live }}</ref> On 7 November 2014, for example, a joint operation by the FBI, ICE Homeland Security investigations and European Law enforcement agencies led to 17 arrests and the seizure of 27 sites containing 400 pages.<ref name="arrests" />{{Dubious | reason=The operation is so successful most likely because of Tor's protocol weakness. Not a good example. (See "Relay early traffic confirmation attack" above.) |date=July 2018}} A late 2014 report by ''[[Der Spiegel]]'' using a new cache of Snowden leaks revealed, however, that {{as of|2012|lc=y}} the NSA deemed Tor on its own as a "major threat" to its mission, and when used in conjunction with other privacy tools such as [[Off-the-Record Messaging|OTR]], Cspace, [[ZRTP]], [[RedPhone]], [[Tails (operating system)|Tails]], and [[TrueCrypt]] was ranked as "catastrophic," leading to a "near-total loss/lack of insight to target communications, presence..."<ref name="spiegel1" /><ref name="spiegel2" /> === 2011 === In March 2011, The Tor Project received the [[Free Software Foundation]]'s 2010 Award for Projects of Social Benefit. The citation read, "Using free software, Tor has enabled roughly 36 million people around the world to experience freedom of access and expression on the Internet while keeping them in control of their privacy and anonymity. Its network has proved pivotal in dissident movements in both [[Iran]] and more recently [[Egypt]]."<ref name="fsf-award" /> === 2012 === In 2012, ''[[Foreign Policy]]'' magazine named Dingledine, Mathewson, and Syverson among its Top 100 Global Thinkers "for making the web safe for whistleblowers".<ref name="fp-top100-thinkers" /> === 2013 === In 2013, [[Jacob Appelbaum]] described Tor as a "part of an ecosystem of software that helps people regain and reclaim their autonomy. It helps to enable people to have agency of all kinds; it helps others to help each other and it helps you to help yourself. It runs, it is open and it is supported by a large community spread across all walks of life."<ref name="verge-applebaum" /> In June 2013, whistleblower [[Edward Snowden]] used Tor to send information about [[PRISM (surveillance program)|PRISM]] to ''[[The Washington Post]]'' and ''[[The Guardian]]''.<ref name="erste-darknet" /> === 2014 === In 2014, the Russian government offered a $111,000 contract to "study the possibility of obtaining technical information about users and users' equipment on the Tor anonymous network".<ref name="ars-111k" /><ref name="pcw-111k" /> In September 2014, in response to reports that [[Comcast]] had been discouraging customers from using the Tor Browser, [[Comcast]] issued a public statement that "We have no policy against Tor, or any other browser or software."<ref>{{cite web |url=https://corporate.comcast.com/comcast-voices/setting-the-record-straight-on-... |title=Setting the Record Straight on Tor |first=Jason |last=Livingood |date=2014-09-15 |quote=The report may have generated a lot of clicks but is totally inaccurate. Comcast is not asking customers to stop using Tor, or any other browser for that matter. We have no policy against Tor, or any other browser or software. Customers are free to use their Xfinity Internet service to visit any website, use any app, and so forth. ... Comcast doesn't monitor our customer's browser software, web surfing or online history. |access-date=5 January 2021 |archive-date=4 January 2021 |archive-url=https://web.archive.org/web/20210104165011/https://corporate.comcast.com/com... |url-status=live }}</ref> In October 2014, The Tor Project hired the public relations firm Thomson Communications to improve its public image (particularly regarding the terms "Dark Net" and "hidden services," which are widely viewed as being problematic) and to educate journalists about the technical aspects of Tor.<ref>{{cite web |last=O'Neill |first=Patrick Howell |date=26 March 2015 |title=Tor's great rebranding |url=http://www.dailydot.com/politics/tor-media-public-relations-perception/ |access-date=19 April 2015 |website=The Daily Dot |archive-date=12 April 2015 |archive-url=https://web.archive.org/web/20150412172355/http://www.dailydot.com/politics/... |url-status=live }}</ref> === 2015 === In June 2015, the [[United Nations special rapporteur|special rapporteur]] from the United Nations' [[Office of the High Commissioner for Human Rights]] specifically mentioned Tor in the context of the debate in the U.S. about allowing so-called [[backdoor (computing)|backdoors]] in encryption programs for law enforcement purposes<ref>{{Cite news |last=Peterson |first=Andrea |date=28 May 2015 |title=U.N. report: Encryption is important to human rights — and backdoors undermine it |url=https://www.washingtonpost.com/blogs/the-switch/wp/2015/05/28/un-report-encr... |newspaper=The Washington Post |access-date=17 September 2017 |archive-date=23 June 2015 |archive-url=https://web.archive.org/web/20150623030700/http://www.washingtonpost.com/blo... |url-status=live }}</ref> in an interview for ''The Washington Post''. In July 2015, the Tor Project announced an alliance with the [[Library Freedom Project]] to establish exit nodes in public libraries.<ref>{{cite web |title=Tor Exit Nodes in Libraries – Pilot (phase one) |url=https://blog.torproject.org/blog/tor-exit-nodes-libraries-pilot-phase-one |access-date=15 September 2015 |website=Tor Project.org |archive-date=8 September 2015 |archive-url=https://web.archive.org/web/20150908012811/https://blog.torproject.org/blog/... |url-status=live }}</ref><ref>{{cite web |title=Library Freedom Project |url=https://libraryfreedomproject.org/ |access-date=15 September 2015 |website=libraryfreedomproject.org |archive-date=19 September 2015 |archive-url=https://web.archive.org/web/20150919100044/https://libraryfreedomproject.org... |url-status=live }}</ref> The pilot program, which established a middle relay running on the excess bandwidth afforded by the Kilton Library in [[Lebanon, New Hampshire]], making it the first library in the U.S. to host a Tor node, was briefly put on hold when the local city manager and deputy sheriff voiced concerns over the cost of defending search warrants for information passed through the Tor exit node. Although the <abbr title="US. Department of Homeland Security">DHS</abbr> had alerted New Hampshire authorities to the fact that Tor is sometimes used by criminals, the Lebanon Deputy Police Chief and the Deputy City Manager averred that no pressure to strong-arm the library was applied, and the service was re-established on 15 September 2015.<ref>{{cite web |last=Doyle-Burr |first=Nora |date=16 September 2015 |title=Despite Law Enforcement Concerns, Lebanon Board Will Reactivate Privacy Network Tor at Kilton Library |url=http://www.vnews.com/photos/inthenews/18620952-95/despite-law-enforcement-co... |url-status=dead |archive-url=https://web.archive.org/web/20150918031540/http://www.vnews.com/photos/inthe... |archive-date=18 September 2015 |access-date=20 November 2015 |website=Valley News}}</ref> U.S. Rep. [[Zoe Lofgren]] (D-Calif) released a letter on 10 December 2015, in which she asked the <abbr title="US. Department of Homeland Security">DHS</abbr> to clarify its procedures, stating that "While the Kilton Public Library's board ultimately voted to restore their Tor relay, I am no less disturbed by the possibility that <abbr title="US. Department of Homeland Security">DHS</abbr> employees are pressuring or persuading public and private entities to discontinue or degrade services that protect the privacy and anonymity of U.S. citizens."<ref>{{cite web |date=10 December 2015 |title=Lofgren questions DHS policy towards Tor Relays |url=https://lofgren.house.gov/news/documentsingle.aspx?DocumentID=398038 |url-status=dead |archive-url=https://web.archive.org/web/20160603144959/https://lofgren.house.gov/news/do... |archive-date=3 June 2016 |access-date=4 June 2016 |website=house.gov}}</ref><ref>{{cite web |last=Geller |first=Eric |date=11 December 2015 |title=Democratic lawmaker wants to know if DHS is sabotaging plans for Tor exit relays |url=http://www.dailydot.com/politics/tor-libraries-dhs-zoe-lofgren-letter/ |access-date=4 June 2016 |website=The Daily Dot |archive-date=10 June 2016 |archive-url=https://web.archive.org/web/20160610194930/http://www.dailydot.com/politics/... |url-status=live }}</ref><ref name="Kopstein2015">{{cite web |last=Kopfstein |first=Janus |date=12 December 2015 |title=Congresswoman Asks Feds Why They Pressured a Library to Disable Its Tor Node |url=https://motherboard.vice.com/read/congresswoman-asks-feds-why-they-pressured... |url-status=live |archive-url=https://web.archive.org/web/20151222171028/http://motherboard.vice.com/read/... |archive-date=22 December 2015 |website=Motherboard}}</ref> In a 2016 interview, Kilton Library IT Manager Chuck McAndrew stressed the importance of getting libraries involved with Tor: "Librarians have always cared deeply about protecting privacy, intellectual freedom, and [[access to information]] (the freedom to read). Surveillance has a very well-documented chilling effect on intellectual freedom. It is the job of librarians to remove barriers to information."<ref>{{Cite news |date=4 August 2016 |title=Tor crusader discuss privacy, freedom with ExpressVPN |language=en-US |work=Home of internet privacy |url=https://www.expressvpn.com/blog/chuck-mcandrew-defends-tor/ |access-date=11 September 2017 }}</ref> The second library to host a Tor node was the Las Naves Public Library in [[Valencia]], Spain, implemented in the first months of 2016.<ref>{{Cite news |last=Gonzalo |first=Marilín |date=26 January 2016 |title=Esta biblioteca valenciana es la segunda del mundo en unirse al proyecto Tor |language=es |work=El Diario |url=http://www.eldiario.es/cultura/tecnologia/privacidad/biblioteca-Valencia-pri... |access-date=4 March 2016 |archive-date=7 March 2016 |archive-url=https://web.archive.org/web/20160307091514/http://www.eldiario.es/cultura/te... |url-status=live }}</ref> In August 2015, an [[IBM]] security research group, called "X-Force", put out a quarterly report that advised companies to block Tor on security grounds, citing a "steady increase" in attacks from Tor exit nodes as well as botnet traffic.<ref>{{cite web |last=Broersma |first=Matthew |date=26 August 2015 |title=IBM Tells Companies To Block Tor Anonymisation Network |url=http://www.techweekeurope.co.uk/security/ibm-companies-tor-175468 |access-date=15 September 2015 |website=TechWeekEurope UK |archive-date=10 September 2015 |archive-url=https://web.archive.org/web/20150910211854/http://www.techweekeurope.co.uk/s... |url-status=live }}</ref> In September 2015, Luke Millanta created OnionView, a web service that plots the location of active Tor relay nodes onto an interactive map of the world. The project's purpose was to detail the network's size and escalating growth rate.<ref>{{Cite magazine |last=Greenberg |first=Andy |date=14 September 2015 |title=Mapping How Tor's Anonymity Network Spread Around the World |url=https://www.wired.com/2015/09/mapping-tors-anonymity-network-spread-around-w... |magazine=Wired |access-date=9 February 2016 |archive-date=3 February 2016 |archive-url=https://web.archive.org/web/20160203154307/http://www.wired.com/2015/09/mapp... |url-status=live }}</ref> In December 2015, [[Daniel Ellsberg]] (of the [[Pentagon Papers]]),<ref>{{cite web |date=26 December 2015 |title=This is What a Tor Supporter Looks Like: Daniel Ellsberg |url=https://blog.torproject.org/blog/what-tor-supporter-looks-daniel-ellsberg |access-date=4 June 2016 |website=The Tor Blog |archive-date=4 March 2016 |archive-url=https://web.archive.org/web/20160304100212/https://blog.torproject.org/blog/... |url-status=live }}</ref> [[Cory Doctorow]] (of [[Boing Boing]]),<ref>{{cite web |date=18 December 2015 |title=This is What a Tor Supporter Looks Like: Cory Doctorow |url=https://blog.torproject.org/blog/what-tor-supporter-looks-cory-doctorow |access-date=4 June 2016 |website=The Tor Blog |archive-date=16 June 2016 |archive-url=https://web.archive.org/web/20160616210816/https://blog.torproject.org/blog/... |url-status=live }}</ref> [[Edward Snowden]],<ref>{{cite web |date=30 December 2015 |title=This is What a Tor Supporter Looks Like: Edward Snowden |url=https://blog.torproject.org/blog/what-tor-supporter-looks-edward-snowden |access-date=4 June 2016 |website=The Tor Blog |archive-date=9 April 2016 |archive-url=https://web.archive.org/web/20160409024736/https://blog.torproject.org/blog/... |url-status=live }}</ref> and artist-activist [[Molly Crabapple]],<ref>{{cite web |date=9 December 2015 |title=This is what a Tor Supporter looks like: Molly Crabapple |url=https://blog.torproject.org/blog/what-tor-supporter-looks-molly-crabapple |access-date=4 June 2016 |website=The Tor Blog |archive-date=16 June 2016 |archive-url=https://web.archive.org/web/20160616210748/https://blog.torproject.org/blog/... |url-status=live }}</ref> amongst others, announced their support of Tor. === 2016 === In March 2016, New Hampshire state representative [[Keith Ammon]] introduced a bill<ref>{{cite web |date=10 March 2016 |title=House Bill 1508: An Act allowing public libraries to run certain privacy software |url=http://www.gencourt.state.nh.us/bill_status/billText.aspx?id=796&txtFormat=html |access-date=4 June 2016 |website=New Hampshire State Government |archive-date=11 April 2017 |archive-url=https://web.archive.org/web/20170411043230/http://www.gencourt.state.nh.us/bill_status/billText.aspx?id=796&txtFormat=html |url-status=live }}</ref> allowing public libraries to run privacy software. The bill specifically referenced Tor. The text was crafted with extensive input from [[Alison Macrina]], the director of the [[Library Freedom Project]].<ref name="Proposed New Hampshire bill">{{cite web |last=O'Neill |first=Patrick Howell |date=18 February 2016 |title=New Hampshire bill allows for libraries' usage of encryption and privacy software |url=http://www.dailydot.com/politics/new-hampshire-tor-library-legislation/ |access-date=10 March 2016 |website=The Daily Dot |archive-date=11 March 2016 |archive-url=https://web.archive.org/web/20160311073326/http://www.dailydot.com/politics/... |url-status=live }}</ref> The bill was passed by the House 268–62.<ref>{{cite web |title=New Hampshire HB1508 – 2016 – Regular Session |url=https://legiscan.com/NH/text/HB1508/id/1288060 |access-date=4 June 2016 |website=legiscan.com |archive-date=29 July 2016 |archive-url=https://web.archive.org/web/20160729171429/https://legiscan.com/NH/text/HB15... |url-status=live }}</ref> Also in March 2016, the first Tor node, specifically a middle relay, was established at a library in Canada, the Graduate Resource Centre (GRC) in the Faculty of Information and Media Studies (FIMS) at the [[University of Western Ontario]].<ref name="Western FIMS relay">{{cite web |date=14 March 2016 |title=Library in FIMS joins global network fighting back against digital surveillance, censorship, and the obstruction of information |url=http://www.fims.uwo.ca/news/2016/library_in_fims_joins_global_network_fighti... |access-date=16 March 2016 |website=FIMS News |archive-date=20 March 2016 |archive-url=https://web.archive.org/web/20160320112332/http://www.fims.uwo.ca/news/2016/... |url-status=live }}</ref> Given that the running of a Tor exit node is an unsettled area of Canadian law,<ref name="Legality of running a Tor exit node in Canada">{{cite web |last=Pearson |first=Jordan |date=25 September 2015 |title=Can You Be Arrested for Running a Tor Exit Node In Canada? |url=https://motherboard.vice.com/read/can-you-be-arrested-for-running-a-tor-exit... |access-date=16 March 2016 |website=Motherboard |archive-date=23 March 2016 |archive-url=https://web.archive.org/web/20160323231601/https://motherboard.vice.com/read... |url-status=live }}</ref> and that in general institutions are more capable than individuals to cope with legal pressures, Alison Macrina of the Library Freedom Project has opined that in some ways she would like to see intelligence agencies and law enforcement attempt to intervene in the event that an exit node were established.<ref name="Fighting the Feds on running a Tor node">{{cite web |last=Pearson |first=Jordan |date=16 March 2016 |title=Canadian Librarians Must Be Ready to Fight the Feds on Running a Tor Node |url=https://motherboard.vice.com/en_ca/read/canadian-librarians-must-be-ready-to... |access-date=16 March 2016 |website=Motherboard |archive-date=19 March 2016 |archive-url=https://web.archive.org/web/20160319083936/http://motherboard.vice.com/en_ca... |url-status=live }}</ref> On 16 May 2016, [[CNN]] reported on the case of core Tor developer isis agora lovecruft,<ref name="lovecruft 2020 tweet">{{cite web |url=https://twitter.com/isislovecruft/status/1258515495851921408 |last=lovecruft |first=isis agora |title=May 7, 2020 Tweet |date=2020-05-07 |quote=my name is isis agora lovecruft not Isis Agora Lovecruft}}</ref> who had fled to Germany under the threat of a subpoena by the FBI during the Thanksgiving break of the previous year. The [[Electronic Frontier Foundation]] legally represented lovecruft.<ref name="Harassment of Isis Agora Lovecruft">{{cite web |last=Pagliery |first=Jose |date=17 May 2016 |title=Developer of anonymous Tor software dodges FBI, leaves US |url=https://money.cnn.com/2016/05/17/technology/tor-developer-fbi/index.html |access-date=17 May 2016 |website=CNN |archive-date=17 May 2016 |archive-url=https://web.archive.org/web/20160517153400/http://money.cnn.com/2016/05/17/t... |url-status=live }}</ref> On 2 December 2016, ''[[The New Yorker]]'' reported on burgeoning [[digital privacy]] and security workshops in the [[San Francisco Bay Area]], particularly at the [[hackerspace]] [[Noisebridge]], in the wake of the [[2016 United States presidential election]]; downloading the Tor browser was mentioned.<ref name="Trump Preparerdness">{{Cite magazine |last=Weiner |first=Anna |date=2 December 2016 |title=Trump Preparedness: Digital Security 101 |url=https://www.newyorker.com/culture/culture-desk/trump-preparedness-digital-se... |magazine=The New Yorker |access-date=20 February 2020 |archive-date=25 October 2020 |archive-url=https://web.archive.org/web/20201025144947/https://www.newyorker.com/culture... |url-status=live }}</ref> Also, in December 2016, Turkey has blocked the usage of Tor, together with ten of the most used [[VPN]] services in Turkey, which were popular ways of accessing banned social media sites and services.<ref>{{cite web |date=19 December 2016 |title=Turkey Partially Blocks Access to Tor and Some VPNs |url=https://www.bleepingcomputer.com/news/government/turkey-partially-blocks-access-to-tor-and-some-vpns/}}</ref> Tor (and [[Bitcoin]]) was fundamental to the operation of the darkweb marketplace [[AlphaBay]], which was taken down in an international law enforcement operation in July 2017.<ref name="forfeit">{{cite web |date=20 July 2017 |title=Forfeiture Complaint |url=https://www.justice.gov/opa/press-release/file/982821/download |publisher=Justice.gov |page=27 |access-date=28 July 2017 |archive-date=23 September 2020 |archive-url=https://web.archive.org/web/20200923012828/https://www.justice.gov/opa/press... |url-status=live }}</ref> Despite federal claims that Tor would not shield a user, however,<ref name="Ten times the size of Silk Road.">{{cite web |last=Leyden |first=John |date=20 July 2017 |title=Cops harpoon two dark net whales in megabust: AlphaBay and Hansa : Tor won't shield you, warn Feds |url=https://www.theregister.co.uk/2017/07/20/dark_net_megabust/ |access-date=21 July 2017 |website=The Register |archive-date=23 May 2020 |archive-url=https://web.archive.org/web/20200523085637/https://www.theregister.co.uk/201... |url-status=live }}</ref> elementary [[operational security]] errors outside of the ambit of the Tor network led to the site's downfall.<ref name="Operational Security Nonexistant">{{cite web |last=McCarthy |first=Kieren |date=20 July 2017 |title=Alphabay shutdown: Bad boys, bad boys, what you gonna do? Not use your Hotmail... ...or the Feds will get you ♪ |url=https://www.theregister.co.uk/2017/07/20/alphabay_hotmail_fbi/ |access-date=21 July 2017 |website=The Register |archive-date=23 May 2020 |archive-url=https://web.archive.org/web/20200523085638/https://www.theregister.co.uk/201... |url-status=live }}</ref> === 2017 === In June 2017 the [[Democratic Socialists of America]] recommended intermittent Tor usage.<ref>{{cite web |url=https://www.dsausa.org/organize/info_security/ |title=Information Security Memo for Members |date=2017-07-11 |publisher=[[Democratic Socialists of America]] |access-date=20 January 2021 |archive-date=20 January 2021 |archive-url=https://web.archive.org/web/20210120104155/https://www.dsausa.org/organize/i... |url-status=live }}</ref><ref>{{cite web |url=https://www.dsausa.org/files/2017/07/DSAInformationSecurityRecommendations_J... |title=INFORMATION SECURITY RECOMMENDATIONS |date=June 2017 |publisher=[[Democratic Socialists of America]] |access-date=20 January 2021 |archive-date=7 September 2020 |archive-url=https://web.archive.org/web/20200907193927/https://www.dsausa.org/files/2017... |url-status=live }}</ref> And in August 2017, according to reportage cybersecurity firms which specialize in monitoring and researching the dark Web (which relies on Tor as its infrastructure) on behalf of banks and retailers routinely share their findings with the [[FBI]] and with other law enforcement agencies "when possible and necessary" regarding illegal content. The Russian-speaking underground offering a crime-as-a-service model is regarded as being particularly robust.<ref name="Dark Web Mainstream Media Coverage">{{cite web |last=Johnson |first=Tim |date=2 August 2017 |title=Shocked by gruesome crime, cyber execs help FBI on dark web |url=http://www.idahostatesman.com/news/nation-world/national/article164797842.ht... |website=Idaho Statesman}}</ref> === 2018 === In June 2018, Venezuela blocked access to the Tor network. The block affected both direct connections to the network and connections being made via bridge relays.<ref name="Venezuela Blocks Tor">{{cite web |last=Brandom |first=Russell |date=25 June 2018 |title=Venezuela is blocking access to the Tor network 16 Just days after new web blocks were placed on local media outlets |url=https://www.theverge.com/2018/6/25/17503680/venezuela-tor-blocked-web-censor... |access-date=26 June 2018 |website=The Verge |archive-date=26 June 2018 |archive-url=https://web.archive.org/web/20180626000651/https://www.theverge.com/2018/6/2... |url-status=live }}</ref> On 20 June 2018, Bavarian police raided the homes of the board members of the non-profit Zwiebelfreunde, a member of [[torservers.net]], which handles the European financial transactions of [[riseup]].net in connection with a blog post there which apparently promised violence against the upcoming [[Alternative for Germany]] convention.<ref name="June 2018 Bavarian Raid">{{cite web |last=Grauer |first=Yael |date=4 July 2018 |title=German police raid homes of Tor-linked group's board members One board member described the police's justification for the raids as a "tenuous" link between the privacy group, a blog, and its email address |url=https://www.zdnet.com/article/german-police-raid-homes-of-tor-linked-groups-... |access-date=6 July 2018 |website=ZDNet |archive-date=6 July 2018 |archive-url=https://web.archive.org/web/20180706000125/https://www.zdnet.com/article/ger... |url-status=live }}</ref><ref name="Police searches homes of Zwiebelfreunde board members as well as OpenLab in Augsburg">{{cite web |last=n/a |first=46halbe |date=4 July 2018 |title=Police searches homes of "Zwiebelfreunde" board members as well as "OpenLab" in Augsburg |url=https://www.ccc.de/en/updates/2018/hausdurchsuchungen-bei-vereinsvorstanden-... |access-date=6 July 2018 |website=Chaos Computer Club |archive-date=4 July 2018 |archive-url=https://web.archive.org/web/20180704101613/https://www.ccc.de/en/updates/201... |url-status=live }}</ref> Tor came out strongly against the raid against its support organization, which provides legal and financial aid for the setting up and maintenance of high-speed relays and exit nodes.<ref name="In Support of Torservers">{{cite web |last=Stelle |first=Sharon |date=5 July 2018 |title=In Support of Torservers |url=https://blog.torproject.org/support-torservers |access-date=6 July 2018 |website=TorProject.org |archive-date=7 July 2018 |archive-url=https://web.archive.org/web/20180707042439/https://blog.torproject.org/suppo... |url-status=live }}</ref> According to Torservers.net, on 23 August 2018 the German court at Landgericht München ruled that the raid and seizures were illegal. The hardware and documentation seized had been kept under seal, and purportedly were neither analyzed nor evaluated by the Bavarian police.<ref>{{cite web |date=24 August 2018 |title=Gericht urteilt: Durchsuchung bei Zwiebelfreunden war rechtswidrig [Update] |url=https://netzpolitik.org/2018/gericht-urteilt-durchsuchung-bei-zwiebelfreunde... |access-date=1 December 2019 |archive-date=12 October 2019 |archive-url=https://web.archive.org/web/20191012011235/https://netzpolitik.org/2018/geri... |url-status=live }}</ref><ref>{{cite web |title=LG München I: Hausdurchsuchungen bei Verein Zwiebelfreunde waren rechtswidrig |url=https://rsw.beck.de/aktuell/meldung/lg-muenchen-i-hausdurchsuchungen-bei-net... |website=Aktuell |access-date=1 December 2019 |archive-date=15 February 2021 |archive-url=https://web.archive.org/web/20210215083404/https://rsw.beck.de/aktuell/daily... |url-status=live }}</ref> Since October 2018, [[internet in China|Chinese online communities]] within Tor have begun to dwindle due to increased efforts to stop them by the Chinese government.<ref>{{cite web |year=2018 |title=China's clampdown on Tor pushes its hackers into foreign backyards |website=[[The Register]] |url=https://www.theregister.co.uk/2018/10/10/russia_china_hacker_forum_compariso... |access-date=10 October 2018 |archive-date=10 October 2018 |archive-url=https://web.archive.org/web/20181010184728/https://www.theregister.co.uk/201... |url-status=live }}</ref> === 2019 === In November 2019, [[Edward Snowden]] called for a full, unabridged [[simplified Chinese]] translation of his autobiography, ''[[Permanent Record (autobiography)|Permanent Record]]'', as the Chinese publisher had violated their agreement by expurgating all mentions of Tor and other matters deemed politically sensitive by the [[Chinese Communist Party]].<ref name="Edward Snowden blew the whistle on how Chinese censors scrubbed his book">{{cite web |last=Stegner |first=Isabella |date=12 November 2019 |title=Edward Snowden blew the whistle on how Chinese censors scrubbed his book |url=https://qz.com/1746780/edward-snowden-calls-out-chinese-censorship-of-his-bo... |url-status=live |archive-url=https://web.archive.org/web/20191115103544/https://qz.com/1746780/edward-sno... |archive-date=15 November 2019 |access-date=12 November 2019 |website=Quartz}}</ref><ref>{{cite web |last=Snowden |first=Edward |date=11 November 2019 |title=The Chinese edition of my new book, #PermanentRecord, has just been censored. |url=https://twitter.com/Snowden/status/1194092273170038784 |url-status=live |archive-url=https://web.archive.org/web/20191112032031/https://twitter.com/Snowden/statu... |archive-date=12 November 2019 |access-date=8 December 2019 |website=Twitter (@Snowden) |language=en }}</ref> === 2021 === On 8 December 2021, the Russian government agency [[Federal Service for Supervision of Communications, Information Technology and Mass Media|Roskomnadzor]] announced it has banned Tor and six VPN services for failing to abide by the [[Russian Internet blacklist]].<ref>{{cite web|date=2021-12-08|title=Russia Bans More VPN Products and TOR - December 8, 2021|url=https://dailynewsbrief.com/2021/12/08/russia-bans-more-vpn-products-and-tor/|access-date=2021-12-11|website=Daily NewsBrief|language=en-US}}</ref> Russian ISPs unsuccessfully attempted to block Tor's main website as well as several bridges beginning on 1 December 2021.<ref>{{cite web |title=Russia Ratchets up Internet Control by Blocking Privacy Service Tor |url=https://www.usnews.com/news/technology/articles/2021-12-08/russia-ratchets-u... |website=U.S. News & World Report |access-date=8 December 2021 |language=en}}</ref> The Tor Project has appealed to Russian courts over this ban.<ref>{{cite web |title=Tor Project appeals Russian court's decision to block access to Tor |url=https://www.bleepingcomputer.com/news/security/tor-project-appeals-russian-c... |access-date=2022-03-08 |website=BleepingComputer |language=en-us}}</ref> === 2022 === In response to [[Internet censorship]] in the [[Russo-Ukraine War]] the [[BBC]] and [[VOA]] have directed Russian audiences to Tor.<ref>{{cite web |url=https://www.wsj.com/articles/russia-rolls-down-internet-iron-curtain-but-gap... |title=Russia Rolls Down Internet Iron Curtain, but Gaps Remain |work=The Wall Street Journal |last1=Schechner |first1=Sam |last2=Hagey |first2=Keach |date=12 March 2022 |access-date=17 March 2022}}</ref> The Russian government increased efforts to block access to Tor through technical and political means, and the network reported an increase in traffic from Russia using its anti-censorship [[Snowflake (software)|Snowflake tool]].<ref name=wired>{{cite magazine|url=https://www.wired.com/story/tor-browser-russia-blocks/ |title=How Tor Is Fighting—and Beating—Russian Censorship |first=Matt |last=Burgess |magazine=[[Wired (magazine)|WIRED]] |date=July 28, 2022 |access-date=2022-07-30}}</ref> Iran implemented rolling internet blackouts during the [[Mahsa Amini protests]], and Tor and Snowflake were used to circumvent them.<ref name=skyrocket>{{cite news |last1=Browne |first1=Ryan |title=VPN use skyrockets in Iran as citizens navigate internet censorship under Tehran's crackdown |url=https://www.cnbc.com/2022/10/07/vpn-use-skyrockets-in-iran-as-citizens-navig... |work=CNBC |language=en}}</ref><ref name=FAZ>{{cite news |last1=Küchemann |first1=Fridtjof |title=Per Snowflake ins TOR-Netzwerk: Online-Gasse für Menschen in Iran |url=https://www.faz.net/aktuell/feuilleton/medien/zugang-fuer-iraner-per-snowfla... |work=[[Frankfurter Allgemeine Zeitung]] |date=27.09.2022 |language=de}}</ref><ref name=rnd>{{cite news |last1=Schwarzer |first1=Matthias |title=Netzsperre im Iran umgehen: Wie "Snowflake" einen Weg ins freie Internet ermöglicht - so kann der Westen helfen |url=https://www.rnd.de/digital/netzsperre-im-iran-umgehen-wie-snowflake-einen-we... |access-date=10 October 2022 |work=[[Redaktions Netzwerk Deutschland]] |publisher=www.rnd.de |date=30.09.2022, 09:00 Uhr |language=de}}</ref><ref name=EFF>{{cite web |last1=Quintin |first1=Cooper |title=Snowflake Makes It Easy For Anyone to Fight Censorship |url=https://www.eff.org/deeplinks/2022/10/snowflake-makes-it-easy-anyone-fight-c... |website=Electronic Frontier Foundation |language=en |date=4 October 2022}}</ref> China, with its highly centralized control of its internet, had effectively blocked Tor.<ref name=wired/> == Improved security == Tor responded to earlier vulnerabilities listed above by patching them and improving security. In one way or another, human (user) errors can lead to detection. The Tor Project website provides the best practices (instructions) on how to properly use the Tor browser. When improperly used, Tor is not secure. For example, Tor warns its users that not all traffic is protected; only the traffic routed through the Tor browser is protected. Users are also warned to use [[HTTPS]] versions of websites, not to [[BitTorrent|torrent]] with Tor, not to enable browser plugins, not to open documents downloaded through Tor while online, and to use safe bridges.<ref>{{cite web |title=The Tor Project | Privacy & Freedom Online |url=https://torproject.org/ |website=torproject.org |access-date=31 October 2019 |archive-date=31 October 2019 |archive-url=https://web.archive.org/web/20191031195458/https://www.torproject.org/ |url-status=live }}</ref> Users are also warned that they cannot provide their name or other revealing information in web forums over Tor and stay anonymous at the same time.<ref name="stayan">{{cite web |title=Tor: Overview – Staying anonymous |url=https://www.torproject.org/about/overview.html.en |access-date=21 September 2016 |archive-date=6 June 2015 |archive-url=https://web.archive.org/web/20150606002957/https://www.torproject.org/about/... |url-status=live }}</ref> Despite intelligence agencies' claims that 80% of Tor users would be de-anonymized within 6 months in the year 2013,<ref name="arstechnica.com">{{cite web |date=31 August 2016 |title=Building a new Tor that can resist next-generation state surveillance |url=https://arstechnica.com/security/2016/08/building-a-new-tor-that-withstands-... |access-date=13 September 2016 |website=arstechnica.com |archive-date=11 September 2016 |archive-url=https://web.archive.org/web/20160911030754/http://arstechnica.com/security/2... |url-status=live }}</ref> that has still not happened. In fact, as late as September 2016, the FBI could not locate, de-anonymize and identify the Tor user who hacked into the email account of a staffer on [[Hillary Clinton]]'s email server.<ref>{{cite web |last=Francis |first=Elias Groll, David |title=FBI: An Account on Clinton's Private Email Server Was Hacked |url=https://foreignpolicy.com/2016/09/02/fbi-an-account-on-clintons-private-emai... |access-date=2020-10-28 |website=Foreign Policy |language=en-US |archive-date=31 October 2020 |archive-url=https://web.archive.org/web/20201031022316/https://foreignpolicy.com/2016/09... |url-status=live }}</ref> The best tactic of law enforcement agencies to de-anonymize users appears to remain with Tor-relay adversaries running poisoned nodes, as well as counting on the users themselves using the Tor browser improperly. For example, downloading a video through the Tor browser and then opening the same file on an unprotected hard drive while online can make the users' real IP addresses available to authorities.<ref>{{cite web |date=16 August 2016 |title=Aussie cops ran child porn site for months, revealed 30 US IPs |url=https://arstechnica.com/tech-policy/2016/08/aussie-cops-ran-child-porn-site-... |access-date=13 September 2016 |website=arstechnica.com |archive-date=8 September 2016 |archive-url=https://web.archive.org/web/20160908002444/http://arstechnica.com/tech-polic... |url-status=live }}</ref> === Odds of detection === When properly used, odds of being de-anonymized through Tor are said to be extremely low. Tor project's co-founder [[Nick Mathewson]] explained that the problem of "Tor-relay adversaries" running poisoned nodes means that a theoretical adversary of this kind is not the network's greatest threat: {{quotation|"No adversary is truly global, but no adversary needs to be truly global," he says. "Eavesdropping on the entire Internet is a several-billion-dollar problem. Running a few computers to eavesdrop on a lot of traffic, a selective denial of service attack to drive traffic to your computers, that's like a tens-of-thousands-of-dollars problem." At the most basic level, an attacker who runs two poisoned Tor nodes—one entry, one exit—is able to analyse traffic and thereby identify the tiny, unlucky percentage of users whose circuit happened to cross both of those nodes. In 2016 the Tor network offers a total of around 7,000 relays, around 2,000 guard (entry) nodes and around 1,000 exit nodes. So the odds of such an event happening are one in two million ({{Frac|1|2000}} × {{Frac|1|1000}}), give or take."<ref name="arstechnica.com" />}} Tor does not provide protection against [[Timing attack|end-to-end timing attack]]s: if an attacker can watch the traffic coming out of the target computer, and also the traffic arriving at the target's chosen destination (e.g. a server hosting a .onion site), that attacker can use statistical analysis to discover that they are part of the same circuit.<ref name=stayan/> === Levels of security === {{More citations needed section|date=December 2021}} Depending on individual user needs, Tor browser offers three levels of security located under the Security Level (the small gray shield at the top-right of the screen) icon > Advanced Security Settings. In addition to encrypting the data, including constantly changing an IP address through a virtual circuit comprising successive, randomly selected Tor relays, several other layers of security are at a user's disposal: # '''Standard (default) – at this security level, all browser features are enabled.''' #* This level provides the most usable experience, and the lowest level of security. # '''Safer – at this security level, the following changes apply:''' #* JavaScript is disabled on non-HTTPS sites. #* On sites where JavaScript is enabled, performance optimizations are disabled. Scripts on some sites may run slower. #* Some mechanisms of displaying math equations are disabled. #* Audio and video (HTML5 media), and WebGL are click-to-play. # '''Safest – at this security level, these additional changes apply:''' #* JavaScript is disabled by default on all sites. #* Some fonts, icons, math symbols, and images are disabled. #* Audio and video (HTML5 media), and WebGL are click-to-play. ==See also== <!-- Please keep entries in alphabetical order & add a short description [[WP:SEEALSO]] --> {{Div col|colwidth=20em|small=yes}} * [[.onion]] * [[Anonymous P2P]] * [[Anonymous web browsing]] * [[Briar (software)|Briar: messaging app on Tor network]] * [[Crypto-anarchism]] * [[Darknet]] * [[Dark web]] * [[Deep web]] * [[Freedom of information]] * [[Freenet]] * [[GNUnet]] * [[I2P]] * [[Internet censorship]] * [[Internet censorship circumvention]] * [[Internet privacy]] * [[Privoxy]] * [[Proxy server]] * [[Psiphon]] * [[Tor2web]] * [[Tor Phone]] * [[torservers.net]] {{div col end}} <!-- Please keep entries in alphabetical order --> {{Portal bar| Anarchism |Free and open-source software |Freedom of speech |Internet }} == Citations == {{Reflist|refs= <ref name="spiegel2">{{Cite news |date=28 December 2014 |title=Presentation from the SIGDEV Conference 2012 explaining which encryption protocols and techniques can be attacked and which not |work=Der Spiegel |url=http://www.spiegel.de/media/media-35535.pdf |access-date=23 January 2015 |archive-date=8 October 2018 |archive-url=https://web.archive.org/web/20181008114248/http://www.spiegel.de/media/media... |url-status=live }}</ref> <ref name="spiegel1">{{Cite news |last=SPIEGEL Staff |date=28 December 2014 |title=Prying Eyes: Inside the NSA's War on Internet Security |work=Der Spiegel |url=http://www.spiegel.de/international/germany/inside-the-nsa-s-war-on-internet... |access-date=23 January 2015 |archive-date=24 January 2015 |archive-url=https://web.archive.org/web/20150124202809/http://www.spiegel.de/internation... |url-status=live }}</ref> <ref name="01-chercheurs">{{cite web |title=Des chercheurs Francais cassent le reseau d'anonymisation Tor |url=http://pro.01net.com/editorial/544024/des-chercheurs-francais-cassent-le-res... |access-date=17 October 2011 |website=01net.com |language=fr |archive-date=16 October 2011 |archive-url=https://web.archive.org/web/20111016155325/http://pro.01net.com/editorial/54... |url-status=live }}</ref> <ref name="andssy-sniper">{{Cite conference |last1=Jansen |first1=Rob |last2=Tschorsch |first2=Florian |last3=Johnson |first3=Aaron |last4=Scheuermann |first4=Björn |year=2014 |title=The Sniper Attack: Anonymously Deanonymizing and Disabling the Tor Network |url=http://www.robgjansen.com/publications/sniper-ndss2014.pdf |conference=21st Annual Network & Distributed System Security Symposium |access-date=28 April 2014 |archive-date=30 June 2014 |archive-url=https://web.archive.org/web/20140630044050/http://www.robgjansen.com/publica... |url-status=live }}</ref> <ref name="ars-111k">{{cite web |last=Gallagher |first=Sean |date=25 July 2014 |title=Russia publicly joins war on Tor privacy with $111,000 bounty |url=https://arstechnica.com/security/2014/07/russia-publicly-joins-war-on-tor-pr... |access-date=26 July 2014 |website=[[Ars Technica]] |archive-date=26 July 2014 |archive-url=https://web.archive.org/web/20140726214634/http://arstechnica.com/security/2... |url-status=live }}</ref> <ref name="ars-feds-narcotics">{{cite web |last=Goodin |first=Dan |date=16 April 2012 |title=Feds shutter online narcotics store that used Tor to hide its tracks |url=https://arstechnica.com/tech-policy/news/2012/04/feds-shutter-online-narcoti... |access-date=20 April 2012 |website=[[Ars Technica]] |archive-date=19 April 2012 |archive-url=https://web.archive.org/web/20120419165308/http://arstechnica.com/tech-polic... |url-status=live }}</ref> <ref name="ars-ranks-cut">{{cite web |last=Gallagher |first=Sean |date=18 April 2014 |title=Tor network's ranks of relay servers cut because of Heartbleed bug |url=https://arstechnica.com/security/2014/04/tor-networks-ranks-of-relay-servers... |access-date=28 April 2014 |website=[[Ars Technica]] |archive-date=1 May 2014 |archive-url=https://web.archive.org/web/20140501163047/http://arstechnica.com/security/2... |url-status=live }}</ref> <ref name="bitmessage-faq">{{cite web |title=Bitmessage FAQ |url=https://bitmessage.org/wiki/FAQ |access-date=17 July 2013 |website=Bitmessage |archive-date=18 August 2013 |archive-url=https://web.archive.org/web/20130818092419/https://bitmessage.org/wiki/FAQ |url-status=live }}</ref> <ref name="bbr-cleaning-up">{{cite web |last=Bode |first=Karl |date=12 March 2007 |title=Cleaning up Tor |url=http://www.broadbandreports.com/shownews/Cleaning-Up-Tor-82218 |access-date=28 April 2014 |website=Broadband.com |archive-date=21 October 2013 |archive-url=https://web.archive.org/web/20131021185626/http://www.broadbandreports.com/s... |url-status=live }}</ref> <ref name="bw-tor-vs">{{Cite news |last=Lawrence |first=Dune |date=23 January 2014 |title=The Inside Story of Tor, the Best Internet Anonymity Tool the Government Ever Built |work=[[Bloomberg Businessweek]] |url=http://www.businessweek.com/articles/2014-01-23/tor-anonymity-software-vs-do... |access-date=28 April 2014 |archive-date=29 March 2014 |archive-url=https://web.archive.org/web/20140329174719/http://www.businessweek.com/artic... |url-status=live }}</ref> <ref name="boston-domestic-abuse">{{cite web |last=LeVines |first=George |date=7 May 2014 |title=As domestic abuse goes digital, shelters turn to counter-surveillance with Tor |url=http://betaboston.com/news/2014/05/07/as-domestic-abuse-goes-digital-shelter... |access-date=8 May 2014 |website=[[Boston Globe]] |archive-date=14 September 2014 |archive-url=https://web.archive.org/web/20140914153110/http://betaboston.com/news/2014/0... |url-status=live }}</ref> <ref name="boston-free-speech-tech">{{cite web |last=McKim |first=Jenifer B. |date=8 March 2012 |title=Privacy software, criminal use |url=http://articles.boston.com/2012-03-08/business/31136655_1_law-enforcement-fr... |archive-url=https://web.archive.org/web/20120312225054/http://articles.boston.com/2012-0... |archive-date=12 March 2012 |website=[[The Boston Globe]]}}</ref> <ref name="ccsw-attacking">{{Cite conference |last1=Herrmann |first1=Dominik |last2=Wendolsky |first2=Rolf |last3=Federrath |first3=Hannes |date=13 November 2009 |title=Website Fingerprinting: Attacking Popular {{sic|hide=y|Privacy Enhancing}} Technologies with the Multinomial Naïve-Bayes Classifier |url=http://epub.uni-regensburg.de/11919/1/authorsversion-ccsw09.pdf |conference=Cloud Computing Security Workshop |location=New York, USA |publisher=[[Association for Computing Machinery]] |access-date=2 September 2010 |book-title=Proceedings of the 2009 ACM Cloud Computing Security Workshop (CCSW) |archive-date=22 April 2011 |archive-url=https://web.archive.org/web/20110422121714/http://epub.uni-regensburg.de/119... |url-status=live }}</ref> <ref name="cnet-arrested">{{Cite news |last=Soghoian |first=Chris |date=16 September 2007 |title=Tor anonymity server admin arrested |work=[[CNET Networks|CNET News]] |url=http://news.cnet.com/8301-13739_3-9779225-46.html |access-date=17 January 2011 |archive-date=10 December 2010 |archive-url=https://web.archive.org/web/20101210151708/http://news.cnet.com/8301-13739_3... |url-status=live }}</ref> <ref name="compaint-ulbricht">{{cite web |last=Turner |first=Serrin |date=27 September 2013 |title=Sealed compaint |url=http://www1.icsi.berkeley.edu/~nweaver/UlbrichtCriminalComplaint.pdf |archive-url=https://web.archive.org/web/20131002221530/http://www1.icsi.berkeley.edu/~nw... |archive-date=2 October 2013 |website=United States of America v. Ross William Ulbricht}}</ref> <ref name="cso-black-market">{{cite web |last=Gregg |first=Brandon |date=30 April 2012 |title=How online black markets work |url=http://www.csoonline.com/article/705316/how-online-black-markets-work |access-date=6 August 2012 |website=CSO Online |archive-date=13 August 2012 |archive-url=https://web.archive.org/web/20120813131253/http://www.csoonline.com/article/... |url-status=live }}</ref> <ref name="economist-bitcoin">{{Cite news |date=29 September 2012 |title=Bitcoin: Monetarists Anonymous |newspaper=[[The Economist]] |url=http://www.economist.com/node/21563752 |access-date=19 May 2013 |archive-date=20 October 2013 |archive-url=https://web.archive.org/web/20131020192331/http://www.economist.com/node/215... |url-status=live }}</ref> <ref name="eff-silk-road">{{cite web |last=Higgins |first=Parker |date=3 October 2013 |title=In the Silk Road Case, Don't Blame the Technology |url=https://www.eff.org/deeplinks/2013/10/silk-road-case-dont-blame-technology |access-date=22 December 2013 |website=[[Electronic Frontier Foundation]] |archive-date=26 January 2014 |archive-url=https://web.archive.org/web/20140126154932/https://www.eff.org/deeplinks/201... |url-status=live }}</ref> <ref name="eff-ssd-tor">{{cite web |title=Surveillance Self-Defense: Tor |url=https://ssd.eff.org/tech/tor |access-date=28 April 2014 |website=[[Electronic Frontier Foundation]] |archive-date=26 June 2014 |archive-url=https://web.archive.org/web/20140626031133/https://ssd.eff.org/tech/tor |url-status=live }}</ref> <ref name="erste-darknet">{{Cite news |last=Gaertner |first=Joachim |date=1 July 2013 |title=Darknet – Netz ohne Kontrolle |language=de |work=[[Das Erste]] |url=http://www.daserste.de/information/wissen-kultur/ttt/sendung/br/20130630-ttt... |url-status=dead |access-date=28 August 2013 |archive-url=https://web.archive.org/web/20130704075422/http://www.daserste.de/informatio... |archive-date=4 July 2013}}</ref> <ref name="fsf-award">{{cite web |title=2010 Free Software Awards announced |url=http://www.fsf.org/news/2010-free-software-awards-announced |access-date=23 March 2011 |website=[[Free Software Foundation]] |archive-date=1 May 2015 |archive-url=https://web.archive.org/web/20150501135149/http://www.fsf.org/news/2010-free... |url-status=live }}</ref> <ref name="fp-top100-thinkers">{{cite web |last=Wittmeyer |first=Alicia P.Q. |date=26 November 2012 |title=The FP Top 100 Global Thinkers |url=https://foreignpolicy.com/articles/2012/11/26/the_fp_100_global_thinkers?pag... |url-status=dead |archive-url=https://web.archive.org/web/20121130221322/http://www.foreignpolicy.com/arti... |archive-date=30 November 2012 |access-date=28 November 2012 |website=[[Foreign Policy]]}}</ref> <ref name="gawker-any-drug">{{cite web |last=Chen |first=Adrian |date=1 June 2011 |title=The Underground Website Where You Can Buy Any Drug Imaginable |url=http://gawker.com/5805928/the-underground-website-where-you-can-buy-any-drug... |url-status=dead |archive-url=https://web.archive.org/web/20110603015735/http://gawker.com/5805928/the-und... |archive-date=3 June 2011 |access-date=20 April 2012 |website=Gawker}}</ref> <ref name="gawker-kiddie-porn">{{cite web |last=Chen |first=Adrian |date=11 June 2012 |title='Dark Net' Kiddie Porn Website Stymies FBI Investigation |url=http://gawker.com/5916994/dark-net-kiddie-porn-website-stymies-fbi-investiga... |access-date=6 August 2012 |website=Gawker |archive-date=14 August 2012 |archive-url=https://web.archive.org/web/20120814195308/http://gawker.com/5916994/dark-ne... |url-status=live }}</ref> <ref name="ghowen-fby-analysis">{{cite web |last=Owen |first=Gareth |title=FBI Malware Analysis |url=http://ghowen.me/fbi-tor-malware-analysis |url-status=dead |archive-url=https://web.archive.org/web/20140417081750/http://ghowen.me/fbi-tor-malware-... |archive-date=17 April 2014 |access-date=6 May 2014}}</ref>{{self-published inline |date=April 2014}} <ref name="guardian-how-nsa">{{Cite news |last=Schneier |first=Bruce |date=4 October 2013 |title=Attacking Tor: how the NSA targets users' online anonymity |work=[[The Guardian]] |url=https://www.theguardian.com/world/2013/oct/04/tor-attacks-nsa-users-online-a... |access-date=22 December 2013 |archive-date=7 August 2017 |archive-url=https://web.archive.org/web/20170807074531/https://www.theguardian.com/world... |url-status=live }}</ref> <ref name="guardian-nsa-target">{{Cite news |last1=Ball |first1=James |last2=Schneier |first2=Bruce |last3=Greenwald |first3=Glenn |date=4 October 2013 |title=NSA and GCHQ target Tor network that protects anonymity of web users |work=[[The Guardian]] |url=https://www.theguardian.com/world/2013/oct/04/nsa-gchq-attack-tor-network-en... |url-status=live |access-date=5 October 2013 |archive-url=https://web.archive.org/web/20190228060200/https://www.theguardian.com/world... |archive-date=28 February 2019}}</ref> <ref name="guardian-peeling">{{Cite news |date=4 October 2013 |title=Peeling back the layers of Tor with EgotisticalGiraffe |work=[[The Guardian]] |url=https://www.theguardian.com/world/interactive/2013/oct/04/egotistical-giraff... |access-date=5 October 2013 |archive-date=5 October 2013 |archive-url=https://web.archive.org/web/20131005030818/http://www.theguardian.com/world/... |url-status=live }}</ref> <ref name="guardianproject-about">{{cite web |title=About |url=https://guardianproject.info/ |access-date=10 May 2011 |website=The Guardian Project |archive-date=16 April 2011 |archive-url=https://web.archive.org/web/20110416232400/http://guardianproject.info/ |url-status=live }}</ref> <ref name="guardianproject-chatsecure">{{cite web |title=ChatSecure: Private Messaging |url=https://guardianproject.info/apps/chatsecure/ |access-date=20 September 2014 |website=The Guardian Project |archive-date=24 September 2014 |archive-url=https://web.archive.org/web/20140924064840/https://guardianproject.info/apps... |url-status=live }}</ref> <ref name="guardianproject-orbot">{{cite web |title=Orbot: Mobile Anonymity + Circumvention |url=https://guardianproject.info/apps/orbot/ |access-date=10 May 2011 |website=The Guardian Project |archive-date=11 May 2011 |archive-url=https://web.archive.org/web/20110511074732/https://guardianproject.info/apps... |url-status=live }}</ref> <ref name="guardianproject-orweb">{{cite web |title=Orweb: Privacy Browser |url=https://guardianproject.info/apps/orweb/ |access-date=10 May 2011 |website=The Guardian Project |archive-date=11 May 2011 |archive-url=https://web.archive.org/web/20110511074727/https://guardianproject.info/apps... |url-status=dead }}</ref> <ref name="guardianproject-proxymob">{{cite web |title=ProxyMob: Firefox Mobile Add-on |url=https://guardianproject.info/apps/proxymob-firefox-add-on/ |access-date=10 May 2011 |website=The Guardian Project |archive-date=11 May 2011 |archive-url=https://web.archive.org/web/20110511074722/https://guardianproject.info/apps... |url-status=dead }}</ref> <ref name="guardianproject-obscuracam">{{cite web |title=Obscura: Secure Smart Camera |url=https://guardianproject.info/apps/obscuracam/ |access-date=19 September 2014 |website=The Guardian Project |archive-date=24 September 2014 |archive-url=https://web.archive.org/web/20140924040527/https://guardianproject.info/apps... |url-status=live }}</ref> <ref name="ieee-low-cost">{{Cite conference|last1=Murdoch |first1=Steven J. |last2=Danezis |first2=George |date=19 January 2006 |chapter=Low-Cost Traffic Analysis of Tor |chapter-url=http://www.cl.cam.ac.uk/~sjm217/papers/oakland05torta.pdf |access-date=21 May 2007 |conference=IEEE Symposium on Security and Privacy |title=Proceedings of the 2005 IEEE Symposium on Security and Privacy. IEEE CS |archive-date=16 June 2007 |archive-url=https://web.archive.org/web/20070616183853/http://www.cl.cam.ac.uk/~sjm217/p... |url-status=live }}</ref> <ref name="iw-info-stealing">{{cite web |last=Samson |first=Ted |date=5 August 2013 |title=Tor Browser Bundle for Windows users susceptible to info-stealing attack |url=http://www.infoworld.com/t/data-security/tor-browser-bundle-windows-users-su... |access-date=28 April 2014 |website=[[InfoWorld]] |archive-date=29 April 2014 |archive-url=https://web.archive.org/web/20140429044651/http://www.infoworld.com/t/data-s... |url-status=live }}</ref> <ref name="jones-forensics">{{Cite book |last=Jones |first=Robert |url=https://archive.org/details/internetforensic0000jone/page/133 |title=Internet forensics |publisher=O'Reilly |year=2005 |isbn=978-0-596-10006-3 |page=[https://archive.org/details/internetforensic0000jone/page/133 133]}}</ref> <ref name="LASTor-2012">{{Cite conference |last1=Akhoondi |first1=Masoud |last2=Yu |first2=Curtis |last3=Madhyastha |first3=Harsha V. |date=May 2012 |title=LASTor: A Low-Latency AS-Aware Tor Client |url=http://lastor.cs.ucr.edu/oakland12.pdf |conference=IEEE Symposium on Security and Privacy |location=Oakland, USA |archive-url=https://web.archive.org/web/20130928003811/http://lastor.cs.ucr.edu/oakland1... |archive-date=28 September 2013 |access-date=28 April 2014 |url-status=dead}}</ref> <ref name="lj-portable">{{cite web |last=Knight |first=John |date=1 September 2011 |title=Tor Browser Bundle-Tor Goes Portable |url=http://www.linuxjournal.com/content/tor-browser-bundle-tor-goes-portable |access-date=28 April 2014 |website=[[Linux Journal]] |archive-date=29 April 2014 |archive-url=https://web.archive.org/web/20140429050524/http://www.linuxjournal.com/conte... |url-status=live }}</ref> <ref name="manils-compromising">{{Cite conference |last1=Manils |first1=Pere |last2=Abdelberri |first2=Chaabane |last3=Le Blond |first3=Stevens |last4=Kaafar |first4=Mohamed Ali |last5=Castelluccia |first5=Claude |last6=Legout |first6=Arnaud |last7=Dabbous |first7=Walid |date=April 2010 |title=Compromising Tor Anonymity Exploiting P2P Information Leakage |url=http://hal.inria.fr/docs/00/47/15/56/PDF/TorBT.pdf |conference=7th USENIX Symposium on Network Design and Implementation |arxiv=1004.1461 |bibcode=2010arXiv1004.1461M |access-date=28 April 2014 |archive-date=6 September 2014 |archive-url=https://web.archive.org/web/20140906211542/http://hal.inria.fr/docs/00/47/15... |url-status=live }}</ref> <ref name="mirror-marques">{{Cite news |last=Best |first=Jessica |date=21 January 2014 |title=Man branded 'largest facilitator of child porn on the planet' remanded in custody again |work=[[Daily Mirror]] |url=https://www.mirror.co.uk/news/world-news/eric-eoin-marques-man-branded-30467... |access-date=29 April 2014 |archive-url=https://web.archive.org/web/20140529103734/http://www.mirror.co.uk/news/worl... |archive-date=29 May 2014 |url-status=live }}</ref> <ref name="ml-rejecting">{{Cite mailing list |url=https://lists.torproject.org/pipermail/tor-relays/2014-April/004336.html |title=Rejecting 380 vulnerable guard/exit keys |date=16 April 2014b |mailing-list=tor-relays |last=Dingledine |first=Roger |access-date=28 April 2014 |archive-date=19 April 2014 |archive-url=https://web.archive.org/web/20140419172640/https://lists.torproject.org/pipe... |url-status=live }}</ref> <ref name="muckrock-hunting-porn">{{cite web |last=Morisy |first=Michael |date=8 June 2012 |title=Hunting for child porn, FBI stymied by Tor undernet |url=http://www.muckrock.com/news/archives/2012/jun/08/hunting-child-porn-fbi-sty... |access-date=6 August 2012 |website=Muckrock |archive-url=https://web.archive.org/web/20120616185438/http://www.muckrock.com/news/arch... |archive-date=16 June 2012 |url-status=live }}</ref> <ref name="openhub-tor">{{cite web |url=https://www.openhub.net/p/tor |title=Tor |website=Open HUB |access-date=27 May 2021 |archive-date=3 September 2014 |archive-url=https://web.archive.org/web/20140903192951/https://www.openhub.net/p/tor |url-status=live }}</ref> <ref name="or-locating">{{cite conference |chapter-url=http://www.onion-router.net/Publications/locating-hidden-servers.pdf |chapter=Locating Hidden Servers |first1=Lasse |last1=Øverlier |first2=Paul |last2=Syverson |title=2006 IEEE Symposium on Security and Privacy (S&P'06) |conference=IEEE Symposium on Security and Privacy |conference-url=http://www.ieee-security.org/TC/SP-Index.html |book-title=Proceedings of the 2006 IEEE Symposium on Security and Privacy |page=1 |publisher=IEEE CS Press |date=21 June 2006 |location=Oakland, Calif. |doi=10.1109/SP.2006.24 <!-- URL required |access-date=9 November 2013 --> |isbn=0-7695-2574-1 |url=http://www.onion-router.net/Publications/locating-hidden-servers.pdf |archive-date=10 August 2013 |archive-url=https://web.archive.org/web/20130810105459/http://www.onion-router.net/Publi... |url-status=live }}</ref> <ref name="pcw-111k">{{cite web |url=http://www.pcworld.com/article/2458420/russian-government-offers-money-for-i... |title=Russian government offers huge reward for help unmasking anonymous Tor users |first=Constantin |last=Lucian |website=[[PC World]] |date=25 July 2014 |access-date=26 July 2014 |archive-date=26 July 2014 |archive-url=https://web.archive.org/web/20140726073307/http://www.pcworld.com/article/24... |url-status=live }}</ref> <ref name=prealpha>{{cite mailing list |url=http://archives.seul.org/or/dev/Sep-2002/msg00019.html |title=Pre-alpha: run an onion proxy now! |last=Dingledine |first=Roger |mailing-list=or-dev@freehaven.net |date=20 September 2002 |access-date=17 July 2008 |url-status=live |archive-date=26 July 2011 |archive-url= https://web.archive.org/web/20110726062025/http://archives.seul.org/or/dev/Sep-2002/msg00019.html}}</ref> <ref name="register-embassy-passwd">{{cite web |title=Tor at heart of embassy passwords leak |last=Goodin |first=Dan |website=[[The Register]] |date=10 September 2007 |access-date=20 September 2007 |url=https://www.theregister.co.uk/2007/09/10/misuse_of_tor_led_to_embassy_passwo... |archive-url=https://web.archive.org/web/20070925124202/http://www.theregister.co.uk/2007... |archive-date=25 September 2007 |url-status=live }}</ref> <ref name="scm-egyptians">{{cite web |url=http://www.scmagazine.com.au/News/246707,egyptians-turn-to-tor-to-organise-d... |title=Egyptians turn to Tor to organise dissent online |first=Nate |last=Cochrane |website=[[SC Magazine]] |date=2 February 2011 |access-date=10 December 2011 |archive-url=https://web.archive.org/web/20111213154629/http://www.scmagazine.com.au/News... |archive-date=13 December 2011 |url-status=live }}</ref> <ref name="shining-light">{{cite conference |chapter-url=http://www.cs.washington.edu/homes/yoshi/papers/Tor/PETS2008_37.pdf |chapter=Shining Light in Dark Places: Understanding the Tor Network |first=Damon |last1=McCoy |first2=Kevin |last2=Bauer |first3=Dirk |last3=Grunwald |first4=Tadayoshi |last4=Kohno |first5=Douglas |last5=Sicker |title=Privacy Enhancing Technologies |series=Lecture Notes in Computer Science |conference=8th International Symposium on Privacy Enhancing Technologies |book-title=Proceedings of the 8th International Symposium on Privacy Enhancing Technologies |pages=63–76 |publisher=Springer-Verlag |location=Berlin, Germany |year=2008 |volume=5134 |isbn=978-3-540-70629-8 |doi=10.1007/978-3-540-70630-4_5 |url=http://www.cs.washington.edu/homes/yoshi/papers/Tor/PETS2008_37.pdf |access-date=13 April 2011 |archive-url=https://web.archive.org/web/20120515200650/http://www.cs.washington.edu/home... |archive-date=15 May 2012 |url-status=live }}</ref> <ref name="sf-tor-hack">{{cite web |url=http://www.securityfocus.com/news/11447 |title=Tor hack proposed to catch criminals |first=Robert |last=Lemos |website=SecurityFocus |date=8 March 2007 |access-date=3 February 2008 |archive-date=10 February 2019 |archive-url= https://web.archive.org/web/20190210044509/https://www.securityfocus.com/new... |url-status=live}}</ref> <ref name="smh-hack-of-year">{{cite web |url=https://www.smh.com.au/news/security/the-hack-of-the-year/2007/11/12/1194766... |title=The hack of the year |first=Patrick |last=Gray |website=[[Sydney Morning Herald]] |date=13 November 2007 |access-date=28 April 2014 |archive-url=https://web.archive.org/web/20140418230200/http://www.smh.com.au/news/securi... |archive-date=18 April 2014 |url-status=live }}</ref> <ref name="tbb-design-document">{{cite web |url=https://www.torproject.org/projects/torbrowser/design/ |title=The Design and Implementation of the Tor Browser [DRAFT] |first1=Mike |last1=Perry |first2=Erinn |last2=Clark |first3=Steven |last3=Murdoch |website=Tor Project |date=15 March 2013 |access-date=28 April 2014 |url-status=live |archive-date=15 August 2014 |archive-url= https://web.archive.org/web/20140815233238/https://www.torproject.org/projects/torbrowser/design/}}</ref> <ref name="thn-compromised">{{cite web |url=http://thehackernews.com/2011/10/tor-anonymizing-network-compromised-by.html |title=Tor anonymizing network compromised by French researchers |website=The Hacker News |date=24 October 2011 |access-date=10 December 2011 |archive-date=7 December 2011 |archive-url=https://web.archive.org/web/20111207111204/http://thehackernews.com/2011/10/... |url-status=live }}</ref> <ref name="torproject-bridges">{{cite web |url=https://www.torproject.org/docs/bridges |title=Tor: Bridges |website=Tor Project |access-date=9 January 2011 |archive-date=12 May 2012 |archive-url=https://web.archive.org/web/20120512012603/https://www.torproject.org/docs/b... |url-status=live }}</ref> <ref name="torproject-conf-hidden">{{cite web |url=https://www.torproject.org/docs/tor-onion-service |title=Configuring Onion Services for Tor |website=Tor Project |access-date=13 December 2018 |archive-date=15 December 2018 |archive-url=https://web.archive.org/web/20181215205835/https://www.torproject.org/docs/t... |url-status=live }}</ref> <ref name="torproject-corepeople">{{cite web |url=https://www.torproject.org/about/corepeople |title=Tor Project: Core People |website=Tor Project |access-date=17 July 2008 |archive-url=https://web.archive.org/web/20110118075745/http://www.torproject.org/about/c... |archive-date=18 January 2011 |url-status=dead }}</ref> <ref name="torproject-fail-both-ends">{{cite web |url=https://wiki.torproject.org/noreply/TheOnionRouter/TorFAQ?action=recall&rev=554#EntryGuards |title=TheOnionRouter/TorFAQ |access-date=18 September 2007 |quote=Tor (like all current practical low-latency anonymity designs) fails when the attacker can see both ends of the communications channel |archive-date=16 September 2020 |archive-url=https://web.archive.org/web/20200916073309/https://trac.torproject.org/projects/tor/wiki/doc/TorFAQ?action=recall&rev=554#EntryGuards |url-status=live }}</ref> <ref name="torproject-faq">{{cite web |url=https://www.torproject.org/docs/faq#WhyCalledTor |title=Tor FAQ: Why is it called Tor? |website=Tor Project |access-date=1 July 2011 |archive-date=17 January 2016 |archive-url=https://web.archive.org/web/20160117155232/https://www.torproject.org/docs/f... |url-status=live }}</ref> <ref name="torproject-faq-abuse">{{cite web |url=https://www.torproject.org/docs/faq-abuse.html.en#WhatAboutCriminals |title=Doesn't Tor enable criminals to do bad things? |website=Tor Project |access-date=28 August 2013 |archive-date=17 August 2013 |archive-url=https://web.archive.org/web/20130817133027/https://www.torproject.org/docs/f... |url-status=live }}</ref> <ref name="torproject-hidden">{{cite web |url=https://www.torproject.org/docs/onion-services.html |title=Tor: Onion Service Protocol |website=Tor Project |access-date=13 December 2018 |archive-date=23 December 2018 |archive-url=https://web.archive.org/web/20181223204417/https://www.torproject.org/docs/o... |url-status=live }}</ref> <!--ref name="torproject-investigation">{{cite web |url=http://boingboing.net/2013/08/04/anonymous-web-host-shut-down.html |title=Tor web host |website=BoingBoing.com |access-date=5 August 2013}}</ref--> <ref name="torproject-news-20140416">{{cite web |url=https://blog.torproject.org/blog/tor-weekly-news-%E2%80%94-april-16th-2014 |title=Tor Weekly News — 16 April 2014 |author=Lunar |website=Tor Project |date=16 April 2014 |access-date=28 April 2014 |archive-date=19 April 2014 |archive-url=https://web.archive.org/web/20140419165608/https://blog.torproject.org/blog/... |url-status=live }}</ref> <ref name="torproject-old-vulnerable">{{cite web |url=https://blog.torproject.org/blog/tor-security-advisory-old-tor-browser-bundl... |title=Tor security advisory: Old Tor Browser Bundles vulnerable |first=Roger |last=Dingledine |website=Tor Project |date=5 August 2013 |access-date=28 April 2014 |archive-date=26 March 2014 |archive-url=https://web.archive.org/web/20140326223617/https://blog.torproject.org/blog/... |url-status=live }}</ref> <ref name="torproject-one-cell">{{cite web |url=https://blog.torproject.org/blog/one-cell-enough |title=One cell is enough to break Tor's anonymity |first=Roger |last=Dingledine |website=Tor Project |date=18 February 2009 |access-date=9 January 2011 |archive-date=20 September 2010 |archive-url=https://web.archive.org/web/20100920113629/http://blog.torproject.org/blog/o... |url-status=live }}</ref> <ref name="torproject-openssl-cve">{{cite web |url=https://blog.torproject.org/blog/openssl-bug-cve-2014-0160 |title=OpenSSL bug CVE-2014-0160 |first=Roger |last=Dingledine |website=Tor Project |date=7 April 2014a |access-date=28 April 2014 |archive-date=10 July 2017 |archive-url=https://web.archive.org/web/20170710101031/https://blog.torproject.org/blog/... |url-status=live }}</ref> <!-- ref name="torproject-pp">{{cite web |url=https://trac.torproject.org/projects/tor/wiki/TheOnionRouter/TorFAQ#Whydowen... |title=TheOnionRouter/TorFAQ |work=Tor Project |access-date=28 December 2010}}</ref> --> <ref name="torproject-rumors-exaggerated">{{cite web |url=https://blog.torproject.org/blog/rumors-tors-compromise-are-greatly-exaggera... |title=Rumors of Tor's compromise are greatly exaggerated |last=phobos |website=Tor Project |date=24 October 2011 |access-date=20 April 2012 |archive-date=30 January 2012 |archive-url=https://web.archive.org/web/20120130020255/https://blog.torproject.org/blog/... |url-status=live }}</ref> <ref name="torproject-sponsors">{{cite web |url=https://www.torproject.org/about/sponsors.html.en |title=Tor: Sponsors |website=Tor Project |access-date=11 December 2010 |archive-date=27 July 2011 |archive-url=https://web.archive.org/web/20110727154342/https://www.torproject.org/about/... |url-status=live }}</ref> <ref name="torstatus">{{cite web |url=https://metrics.torproject.org/networksize.html |title=Tor Server Status |publisher=Tor Project - Metrics |access-date=7 July 2021}}</ref> <ref name="tp-blacklisting">{{cite web |url=http://threatpost.com/tor-begins-blacklisting-exit-nodes-vulnerable-to-heart... |title=Tor begins blacklisting exit nodes vulnerable to Heartbleed |first=Michael |last=Mimoso |website=Threat Post |date=17 April 2014 |access-date=28 April 2014 |archive-date=19 April 2014 |archive-url=https://web.archive.org/web/20140419155907/http://threatpost.com/tor-begins-... |url-status=live }}</ref> <ref name="twe-zmap">{{cite web|url=http://www.techweekeurope.co.uk/news/zmap-internet-scan-zero-day-125374|title=Zmap's Fast Internet Scan Tool Could Spread Zero Days In Minutes|last=Judge|first=Peter|date=20 August 2013|website=TechWeek Europe|url-status=dead|archive-url=https://web.archive.org/web/20130824142042/http://www.techweekeurope.co.uk/news/zmap-internet-scan-zero-day-125374|archive-date=24 August 2013}}</ref> <ref name="usenix-bad-apple">{{cite conference |url=https://www.usenix.org/events/leet11/tech/full_papers/LeBlond.pdf |title=One Bad Apple Spoils the Bunch: Exploiting P2P Applications to Trace and Profile Tor Users |first1=Stevens |last1=Le Blond |first2=Pere |last2=Manils |first3=Abdelberi |last3=Chaabane |first4=Mohamed |last4=Ali Kaafar |first5=Claude |last5=Castelluccia |first6=Arnaud |last6=Legout |first7=Walid |last7=Dabbous |conference=4th USENIX Workshop on Large-Scale Exploits and Emergent Threats (LEET '11) |publisher=National Institute for Research in Computer Science and Control |date=March 2011 |access-date=13 April 2011 |archive-date=27 April 2011 |archive-url=https://web.archive.org/web/20110427023454/https://www.usenix.org/events/lee... |url-status=live }}</ref> <ref name="usenix-design">{{cite conference |last1=Dingledine |first1=Roger |last2=Mathewson |first2=Nick |last3=Syverson |first3=Paul |title=Tor: The Second-Generation Onion Router |book-title=Proc. 13th USENIX Security Symposium |place=San Diego, California |date=13 August 2004 |url=http://www.usenix.org/events/sec04/tech/dingledine.html |access-date=17 November 2008 |conference= |archive-date=9 August 2011 |archive-url=https://web.archive.org/web/20110809060244/http://www.usenix.org/events/sec0... |url-status=live }}</ref> <ref name="vuze-tor">{{cite web |url=http://wiki.vuze.com/w/Tor |title=Tor |website=Vuze |access-date=3 March 2010 |archive-date=30 April 2013 |archive-url=https://web.archive.org/web/20130430035208/http://wiki.vuze.com/w/Tor |url-status=live }}</ref> <ref name="verge-applebaum">{{cite web |url=https://www.theverge.com/2013/3/11/4091186/interview-uncut-jacob-appelbaum |title=Interview uncut: Jacob Appelbaum |author=Sirius, R. U. |website=theverge.com |date=11 March 2013 |access-date=17 September 2017 |archive-date=20 October 2014 |archive-url=https://web.archive.org/web/20141020223354/http://www.theverge.com/2013/3/11... |url-status=live }}</ref> <ref name="wired-fbi-controlled">{{cite magazine |url=https://www.wired.com/threatlevel/2013/09/freedom-hosting-fbi/ |title=FBI Admits It Controlled Tor Servers Behind Mass Malware Attack |first=Kevin |last=Poulsen |magazine=[[Wired (magazine)|Wired]] |date=13 September 2013 |access-date=22 December 2013 |archive-date=21 December 2013 |archive-url=https://web.archive.org/web/20131221024649/http://www.wired.com/threatlevel/... |url-status=live }}</ref> <ref name="wired-feds-are-suspects">{{cite magazine |url=https://www.wired.com/2013/08/freedom-hosting/ |title=Feds Are Suspects in New Malware That Attacks Tor Anonymity |first=Kevin |last=Poulsen |magazine=[[Wired (magazine)|Wired]] |date=8 May 2013 |access-date=29 April 2014 |archive-date=29 April 2014 |archive-url=https://web.archive.org/web/20140429202100/http://www.wired.com/2013/08/free... |url-status=live }}</ref> <ref name="wired-rogue-nodes">{{cite news |url=https://www.wired.com/politics/security/news/2007/09/embassy_hacks?currentPa... |title=Rogue Nodes Turn Tor Anonymizer Into Eavesdropper's Paradise |first1=Kim |last1=Zetter |author-link=Kim Zetter |newspaper=[[Wired (magazine)|Wired]] |date=10 September 2007 |access-date=16 September 2007 |archive-date=31 December 2008 |archive-url=https://web.archive.org/web/20081231175940/http://www.wired.com/politics/sec... |url-status=live }}</ref> <ref name="wp-feds-pay">{{cite news |url=https://www.washingtonpost.com/blogs/the-switch/wp/2013/09/06/the-feds-pays-... |title=The feds pay for 60 percent of Tor's development. Can users trust it? |first=Brian |last=Fung |work=The Switch |publisher=Washington Post |date=6 September 2013 |access-date=6 February 2014 |archive-date=9 September 2013 |archive-url=https://archive.today/20130909202619/http://www.washingtonpost.com/blogs/the... |url-status=live }}</ref> <ref name="wsj-anonymous-contraversial">{{cite news |url=https://www.wsj.com/articles/SB10001424127887324677204578185382377144280 |title=Tor: an anonymous, and controversial, way to web-surf |first=Geoffrey A. |last=Fowler |work=[[Wall Street Journal]] |date=17 December 2012 |access-date=19 May 2013 |archive-date=11 March 2015 |archive-url=https://web.archive.org/web/20150311064250/http://www.wsj.com/articles/SB100... |url-status=live }}</ref> <ref name="wu8-ubuntu-ppa">{{cite web |url=http://www.webupd8.org/2013/12/tor-browser-bundle-ubuntu-ppa.html |title=Tor Browser Bundle Ubuntu PPA |first=Andrei |last=Alin |website=Web Upd8 |date=2 December 2013 |access-date=28 April 2014 |archive-date=21 April 2014 |archive-url=https://web.archive.org/web/20140421220450/http://www.webupd8.org/2013/12/to... |url-status=live }}</ref> <ref name="xakep-whole-hog">{{cite web |url=http://eng.xakep.ru/link/51074/ |title=Включаем Tor на всю катушку |trans-title=Make Tor go the whole hog |first=Антон |last=Жуков |website=Xakep |date=15 December 2009 |access-date=28 April 2014 |url-status=dead |archive-url=https://web.archive.org/web/20130901035137/http://eng.xakep.ru/link/51074/ |archive-date=1 September 2013 }}</ref> <ref name="arrests">{{Cite news |url=https://www.bbc.co.uk/news/technology-29987373 |title=Dark net experts trade theories on 'de-cloaking' after raids |date=7 November 2014 |access-date=12 November 2014 |newspaper=BBC News |last1=Lee |first1=Dave |archive-date=12 November 2014 |archive-url=https://web.archive.org/web/20141112165655/http://www.bbc.co.uk/news/technol... |url-status=live }}</ref> <!--ref name=technologyreview>{{cite news |title=Home Internet with Anonymity Built In |first=Tom |last=Simonite |url=http://www.technologyreview.com/web/26981/?a=f |newspaper=[[Technology Review]] |date=22 December 2010 |access-date=14 May 2011}}</ref--> <ref name="tor-gitlab-repoanalytics">{{cite web |url=https://gitlab.torproject.org/tpo/core/tor/-/graphs/main/charts |title=Repository Analytics |website=Tor Project GitLab |access-date=24 August 2022 |url-status=live }}</ref> }} == General and cited references == {{Refbegin}} * {{Cite book |title=Computer Privacy Handbook |first=Andre |last=Bacard |isbn=978-1-56609-171-8|date=1 January 1995 }} * {{cite journal |last1=Lund |first1=Brady |first2=Matt |last2=Beckstrom |date=2021 |title=The Integration of Tor into Library Services: An Appeal to the Core Mission and Values of Libraries |journal=Public Library Quarterly |volume=40 |issue=1 |pages=60–76 |doi=10.1080/01616846.2019.1696078 |s2cid=214213117 }} * {{Cite book |title=Understanding the Usage of Anonymous Onion Services: Empirical Experiments to Study Criminal Activities in the Tor Network |first=Juha |last=Nurmi |isbn=978-952-03-1091-2 |date=24 May 2019 }} * {{Cite book |title=Applied Cryptography |first=Bruce |last=Schneier |author-link=Bruce Schneier |isbn=978-0-471-11709-4|date=1 November 1995 }} * {{Cite book |title=Email Security |first=Bruce |last=Schneier |author-link=Bruce Schneier |isbn=978-0-471-05318-7 |date=25 January 1995 |url-access=registration |url=https://archive.org/details/emailsecurityhow0000schn }} {{Refend}} ==External links== {{Commons category|Tor project}} * {{Official website}} * [http://freehaven.net/anonbib/ Anonymity Bibliography] * [https://2019.www.torproject.org Old website] * [https://web.archive.org/web/20171220172642/https://www.torproject.org/getinv... Archived: Official List of mirror websites] * [https://www.youtube.com/watch?v=JWII85UlzKw&index=1&list=PLwyU2dZ3LJErtu3GGElIa7VyORE2B6H1H Animated introduction] * [https://media.ccc.de/v/31c3_-_6112_-_en_-_saal_2_-_201412301715_-_tor_hidden... Tor: Hidden Services and Deanonymisation] presentation at the 31st Chaos Computer Conference * [https://torflow.uncharted.software/ TorFlow], a dynamic visualization of data flowing over the Tor network * [https://media.ccc.de/v/32c3-7322-tor_onion_services_more_useful_than_you_thi... Tor onion services: more useful than you think] in a 2016 presentation at the 32nd Annual [[Chaos Communication Congress]] * [https://www.youtube.com/watch?v=xGIE7KTJiBY A core Tor developer lectures at the] [[Radboud University Nijmegen]] in The Netherlands on anonymity systems in 2016 * [https://web.archive.org/web/20161019151220/https://people.torproject.org/~is... A technical presentation given at the] [[University of Waterloo]] in Canada: Tor's Circuit-Layer Cryptography: Attacks, Hacks, and Improvements * [https://www.youtube.com/watch?v=ShrZ4B9R3NQ A Presentation at the March 2017 BSides Vancouver Conference on security practices on Tor's hidden services given by] [[Sarah Jamie Lewis]] {{Tor project}} {{Tor hidden services}} {{Internet censorship circumvention technologies}} {{Navboxes|list= {{Cryptographic software}} {{Privacy}} {{Routing software}} {{Web browsers|desktop}} }} [[Category:Tor (anonymity network)| ]] [[Category:Tor onion services|.]] [[Category:2002 software]] [[Category:Anonymity networks]] [[Category:Application layer protocols]] [[Category:Computer networking]] [[Category:Cross-platform free software]] [[Category:Cross-platform software]] [[Category:Cryptographic protocols]] [[Category:Cryptographic software]] [[Category:Cryptography]] [[Category:Dark web]] [[Category:File sharing]] [[Category:Free network-related software]] [[Category:Free routing software]] [[Category:Free software programmed in C]] [[Category:Free software programmed in Rust]] [[Category:Hash based data structures]] [[Category:Internet privacy software]] [[Category:Internet properties established in 2002]] [[Category:Internet protocols]] [[Category:Internet security]] [[Category:Internet Standards]] [[Category:Key-based routing]] [[Category:Mix networks]] [[Category:Onion routing]] [[Category:Overlay networks]] [[Category:Proxy servers]] [[Category:Secure communication]] [[Category:Software using the BSD license]]