- Anonymous P2P
An anonymous P2P computer network is a particular type of
peer-to-peernetwork in which the users are anonymous or pseudonymous by default. The primary difference between regular and anonymous networks is in the routing method of their respective network architectures. These networks allow the unfettered free flow of information.
Interest in anonymous P2P has increased in recent years for many reasons, including distrust of governments (especially in undemocratic regimes), mass
surveillanceand data retention, and lawsuits against bloggers.Julien Pain, editor (2005). [http://www.rsf.org/rubrique.php3?id_rubrique=542 Reporters Without Borders handbook for bloggers and cyber-dissidents] . Retrieved 2008-01-23.] Such networks may also appeal to those wishing to share copyrighted files illegally - organizations such as the Recording Industry Association of Americaand the British Phonographic Industryhave successfully tracked and sued users on non-anonymous P2P networks.Electronic Frontier Foundation (2005). [http://www.eff.org/IP/P2P/RIAAatTWO_FINAL.pdf RIAA v. The People: Two Years Later] . Retrieved 2008-03-05.]
Uses of anonymous P2P
There are many reasons to use anonymous P2P technology; most of them are generic to all forms of online anonymity.
P2P users who desire anonymity usually do so as they do not wish to be identified as a publisher (sender), or reader (receiver), of information. Common reasons include:
* The material or its distribution is illegal or incriminating
* Material is legal but socially deplored, embarrassing or problematic in the individual's social world (for example, anonymity is seen as a key requirement for organizations like
* Fear of retribution (whistleblowers, unofficial leaks, and activists who do not believe in restrictions on information or knowledge)
* Censorship at the local, organizational, or national level
* Personal privacy preferences such as preventing
A particularly open view on legal and illegal content is given in [http://freenetproject.org/index.php?page=philosophy The Philosophy Behind Freenet] .
Governments are also interested in anonymous P2P technology. The
United States Navyfunded the original onion routingresearch that led to the development of the Tor network, which is now funded by the Electronic Frontier Foundation.
Arguments for and against anonymous P2P networks
While anonymous P2P systems may support the protection of unpopular speech, they may also protect illegal activities not protected under some free speech laws, such as
fraud, libel, the exchange of illegal pornography, the unauthorized copying of copyrighted works, or the planning of criminal activities. Critics of anonymous P2P systems hold that the advantages offered by such systems do not outweigh these disadvantages, and that other communication channels are already sufficient for unpopular speech.
Some proponents of anonymous P2P systems believe that all restrictions on free speech serve authoritarian interests. Others argue that information itself is ethically neutral, and that it is the people acting upon the information that can be good or evil. Perceptions of good and evil can also change (see
moral panic); for example, if anonymous peer-to-peer networks had existed in the 1950s or 1960s, they might have been targeted for carrying information about civil rightsor anarchism.
Easily accessible anonymous P2P networks are seen by some as a democratization of
encryptiontechnology, giving the general populace access to secure communications channels already used by governments. Supporters of this view argue that anti-surveillance technologies help to equalize power between governments and their people,Russell D. Hoffmann (1996). [http://www.animatedsoftware.com/hightech/philspgp.htm Interview with author of PGP (Pretty Good Privacy)] . Transcript of a radio interview, retrieved 2008-01-21.] which is the actual reason for banning them. Some believe that monitoring of the populace helps to contain threats to the "consensual view of established authority"John Pilger (2002). [http://www.zmag.org/content/MainstreamMedia/pilger_britishjournalism.cfm Impartiality of British Journalism] . ZNet article, retrieved 2008-02-11.] or threats to the continuity of power structures and privilege.
Freedom of speech
Some claim that true
freedom of speech, especially on controversial subjects, is difficult or impossible unless individuals can speak anonymously. If anonymity is not possible, one could be subjected to threats or reprisals for voicing an unpopular view. This is one reason why voting is done by secret ballot in many democracies. Controversial information which a party wants to keep hidden, such as details about corruption issues, is often published or leaked anonymously.
Anonymous blogging is one widespread use of anonymous networks. While anonymous blogging is possible on the non-anonymous internet to some degree too, a provider hosting the blog in question might be forced to disclose the blogger's IP address (see a case of Google revealing an anonymous blogger's identity [Declan McCullagh (2007). [http://www.news.com/8301-13578_3-9824638-38.html Google: We had no choice in Israel ID request] . CNET News.com article, retrieved
2008-02-11.] ). Anonymous networks provide a better degree of anonymity. Flogs in Freenetand Syndiein i2pare some examples of anonymous blogging technologies.
One argument for anonymous blogging is a delicate nature of work situation. Sometimes a blogger writing under his/her real name faces a choice between either staying silent or causing a harm to himself, his colleagues or the company he works for. [Bill Vallicella (2004). [http://maverickphilosopher.blogspot.com/2004/07/reasons-for-anonyblogging.html Reasons for 'Anonyblogging'] . Maverick Philosopher blog, retrieved
Risk of lawsuits is another reason. Some bloggers have faced multi-million dollar lawsuits [Media Bloggers Association (2006). [http://www.mediabloggers.org/mba-news/mba-member-hit-with-multi-million-dollar-federal-lawsuit MBA Member Hit With Multi-Million Dollar Federal Lawsuit] . Retrieved
2008-02-11.] that were later dropped completely; [Associated Press (2006). [http://www.boston.com/news/local/maine/articles/2006/05/06/ad_agency_drops_lawsuit_against_maine_blogger/ Ad agency drops lawsuit against Maine blogger] . Retrieved 2008-02-11.] anonymous blogging provides protection against such risks.
Censorship via Internet domain names
On the non-anonymous internet, a domain name like "mysite.com" is a key to accessing information. The censorship of the Wikileaks website [ [http://www.wikileaks.org/wiki/WIKILEAKS.INFO_censored_by_eNom_and_Demand_Media WIKILEAKS.INFO censored by eNom and Demand Media] . Retrieved
2008-03-09.] shows that domain names are extremely vulnerable to censorship. Some domain registrars have suspended customers' domain names even in the absence of a court order.
For the affected customer, blocking of a domain name is a far bigger problem than a registrar refusing to provide a service; typically, the registrar keeps full control over the domain names in question.In the case of a European travel agency, more than 80 .com web sites were shut down without any court process and held by the registrar since then. The travel agency had to rebuild the sites under the .net
top-level domaininstead. [Adam Liptak (2008). [http://www.nytimes.com/2008/03/04/us/04bar.html A Wave of the Watch List, and Speech Disappears] . The New York Times, 2008-03-04. Retrieved 2008-03-09.]
Anonymous networks, on the other hand, do not rely on domain name registrars. For example, Freenet implements censorship-resistant URLs based on
public-key cryptography: only a person having the correct private key is able to update the URL or take it down.
Control over online tracking
Anonymous P2P also has value in normal daily communication. When communication is anonymous, the decision to reveal the identities of the communicating parties is left up to the parties involved and is not available to a third party. Often there is no need or desire by the communicating parties to reveal their identities. As a matter of personal freedom, many people do not want processes in place by default which supply unnecessary data. In some cases such data could be compiled into histories of their activities.
For example, the current phone system transmits caller ID information by default to the called party. If one is calling to make an inquiry about a product or the time of a movie, the person called has a record of the phone number that called, and can obtain the name, address and other information about the caller. If one were to walk into a store and make a similar inquiry all this personal information would not be involved. Anonymous P2P simply allows for a currently-existing activity in “
meatspace” to now occur over a communications network.
Effects of surveillance on lawful activity
Online surveillance, such as recording and retaining details of web and e-mail traffic, may have effects on lawful activities. Dawinder S. Sidhu (2007). [http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1002145 The chilling effect of government surveillance programs on the use of the internet by Muslim-Americans] . University of Maryland Law Journal of Race, Religion, Gender and Class.] People may be deterred from accessing or communicating legal information because they know of possible surveillance and believe that such communication may be seen as suspicious.
For example, one blog visitor expressed his worries about viewing the
Al Jazeerachannel online: "While you may argue that Al Jazeera is not pro-terrorism, that doesn't keep people in DHS and NSA from assuming that people who watch a lot of 'Al Jazeera' might be pro-terrorist and maybe should be put on a list to see if they make phone calls to other 'pro-terrorists' or maybe they should be added to the list of people who need extra scrutiny when they fly." [http://www.metafilter.com/56329/Al-Jazeera-English MetaFilter community weblog] Retrieved 2008-01-20.]
According to law professor Daniel J. Solove, such effects "harm society because, among other things, they reduce the range of viewpoints being expressed and the degree of freedom with which to engage in political activity." Daniel J. Solove (2006). [http://papers.ssrn.com/sol3/papers.cfm?abstract_id=998565 "I've got nothing to hide" and other misunderstandings of privacy] . San Diego Law Review, Vol. 44.]
Access to censored and copyrighted material
Most countries ban or censor the publication of certain books and movies, and certain types of content such as
child pornography. Other material is legal to possess but not to distribute; for example, copyright and software patentlaws may forbid its distribution. These laws are difficult or impossible to enforce in anonymous P2P networks.
Anonymous online money
anonymous money, it becomes possible to arrange anonymous markets where one can buy and sell just about anything anonymously. Anonymous money could be used to avoid taxcollection. However, any transfer of physical goods between two parties could compromise anonymity, and the value of any anonymous currency must ultimately be based on physical goods. Rob Thomas, Jerry Martin (2006). [http://www.usenix.org/publications/login/2006-12/openpdfs/cymru.pdf The underground economy: priceless] . Retrieved 2008-01-20.]
Some argue that conventional
cashprovides a similar kind of anonymity, and that existing laws are adequate to combat crimes like tax evasionthat might result from the use of anonymous cash, whether online or offline.
Functioning of anonymous P2P
Anonymity and pseudonymity
Some of the networks commonly referred to as "anonymous P2P" are truly anonymous, in the sense that network nodes carry no identifiers. Others are actually pseudonymous: instead of being identified by their IP addresses, nodes are identified by pseudonyms such as cryptographic keys. For example, each node in the
MUTEnetwork has an overlay address that is derived from its public key. This overlay address functions as a pseudonym for the node, allowing messages to be addressed to it. In Freenet, on the other hand, messages are routed using keys that identify specific pieces of data rather than specific nodes; the nodes themselves are anonymous.
The term "anonymous" is used to describe both kinds of network because it is difficult -- if not impossible -- to determine whether a node that sends a message originated the message or is simply forwarding it on behalf of another node. Every node in an anonymous P2P network acts as a universal sender and universal receiver to maintain anonymity. If a node was only a receiver and did not send, then neighbouring nodes would know that the information it was requesting was for itself only, removing any
plausible deniabilitythat it was the recipient (and consumer) of the information. Thus, in order to remain anonymous, nodes must ferry information for others on the network.
Spam and DoS attacks in anonymous networks
Originally, anonymous networks were operated by small and friendly communities of developers. As interest in anonymous P2P increased and the user base grew, malicious users inevitably appeared and tried different attacks. This is similar to the Internet, where widespread use has been followed by waves of spam and distributed
denial-of-service attacks. Such attacks may require different solutions in anonymous networks. For example, blacklisting of originator network addresses does not work because anonymous networks conceal this information.
Opennet and darknet (Friend to Friend) network types
Like conventional P2P networks, anonymous P2P networks can implement either opennet or
darknet(often named Friend to Friend) network type. This describes how a node on the network selects peer nodes:
* In opennet network, peer nodes are discovered automatically. There is no configuration required but little control available over which nodes become peers.
* In a darknet network, users manually establish connections with nodes run by people they know. Darknet typically needs more effort to set up but a node only has trusted nodes as peers.
Some networks like
Freenetsupport both network types simultaneously (a node can have 5 manually added darknet peer nodes and 5 automatically selected opennet peers) .
In a friend-to-friend (or F2F) network, users only make direct connections with people they know. Many F2F networks support indirect anonymous or pseudonymous communication between users who do not know or trust one another. For example, a node in a friend-to-friend overlay can automatically forward a file (or a request for a file) anonymously between two friends, without telling either of them the other's name or IP address. These friends can in turn forward the same file (or request) to their own friends, and so on.Users in a friend-to-friend network cannot find out who else is participating beyond their own circle of friends, so F2F networks can grow in size without compromising their users' anonymity.
friend-to-friendnetworks allow the user to control what kind of files can be exchanged with friends within the node, in order to stop them from exchanging files that user disapproves of.
Advantages and disadvantages of opennet compared to darknet are disputed, see
Friend to Friendarticle for summary.
List of anonymous P2P networks and clients
= Pseudonymous P2P clients =
I2P- an anonymizing (overlay) network with lots of applications running on top of it (free/open source, written in Java)
ANts P2P- a P2P file sharing system which anonymizes and encrypts traffic, and supports HTTP publishing
* Vuze (formerly Azureus) - a
BitTorrent clientwith the option of using I2Por Tor (open source, written in Java)
* Perfect Dark Microsoft-only file sharing program in Japan, possibly the successor to Share and Winny
Freenet- a censorship-resistant distributed file systemfor anonymous publishing (open source, written in Java)
* Entropy - a "
Freenetalternative" discontinued on July 9, 2004 due to uncertainty about the security of the McEliece cryptosystem.
GNUnet- P2P framework, includes anonymous file sharing as its primary application ( GNUproject, written in C)
I2phex- a Gnutella client which communicates anonymously through I2P
* Imule - an emule port running under I2P network
Marabunta- an anonymous distributed P2P network for chatting only, which uses only UDP
MUTE- an anonymizing file sharing client.
Nodezilla- an anonymizing, closed source network layer upon which applications can be built (written in C++ and Java)
* OFF System - a P2P
distributed file systemthrough which all shared files are represented by randomized data blocks
Omemo- an open source social storage platform (p2p virtual hard drive)
Rodi- a file sharing client which allows for a low degree of anonymity
RShare- a file sharing system which anonymizes and encrypts the traffic
* Share - the successor to Winny
StealthNet- a new branch of RShare, richer in features and heavily developed by the community
Syndie- a content syndication program that operates over numerous anonymous and non-anonymous networks
* Tor - While [http://tor.eff.org Tor] is not a P2P client itself, it provides a method for other P2P programs to become anonymous. It is also one of the larger research projects for anonymous networks.
Winny- a P2P client that is very popular in Japan (freeware, written in C++ for Windows)
Private P2P clients
Private P2Pnetworks are P2P networks that only allow some mutually trusted computers to share files. This can be achieved by using a central server or hub to authenticate clients, in which case the functionality is similar to a private FTPserver, but with files transferred directly between the clients. Alternatively, users can exchange passwords or keys with their friends to form a decentralized network.
Friend-to-friend networks are P2P networks that allows users only to make direct connections with people they know. Passwords or digital signatures can be used for authentication.
Hypothetical or defunct networks
Crowds- Reiter and Rubin's system for "blending into a crowd"
Invisible IRC Project- anonymous IRC.
Infrastructure for Resilient Internet Systems
Mnet- a distributed file system.
* Phantom - a fully decentralized high-throughput anonymization network.
Anonymous P2P in a wireless mesh network
It is possible to implement anonymous P2P used on a
wireless mesh network: unlike fixed internet connections, users don't need to sign up with an ISP to participate in such a network, and are only identifiable through their hardware. Even if a government were to outlaw the use of wireless P2P software, it would be difficult to enforce such a ban without a considerable infringement of personal freedoms. Alternatively, the government could outlaw the purchase of the wireless hardware itself, or require every wireless device to be registered under the owner's name. Protocols for wireless mesh networks are OLSRand the follow-up protocol B.A.T.M.A.N., which is designed for decentralized auto-IP assignment.
Comparison of file sharing applications
Dining cryptographers protocol
* [http://www.anonymous-p2p.org/ Anonymous-p2p.org]
* [http://board.planetpeer.de/ Planet Peer Board] - discussion on anonymous P2P
* [http://www.planetpeer.de/wiki/ Planet Peer Wiki] - a
wikiabout various anonymous P2P applications
* [http://www.lix.polytechnique.fr/~tomc/P2P/index.html A Survey of Anonymous Peer-to-Peer File-Sharing]
* [http://dienst.isti.cnr.it/Dienst/UI/2.0/Describe/ercim.cnr.iit/2003-B4-03?tiposearch=cnr&langver= Models for Anonymous-p2p Dr. Fabio Dianda - CNR - Italy]
* [http://anonet.org anoNet]
* [http://current.cs.ucsb.edu/projects/cashmere/ Cashmere : resilient anonymous routing]
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