Anonymity
Encyclopedia
Anonymity is derived from the Greek
Koine Greek
Koine Greek is the universal dialect of the Greek language spoken throughout post-Classical antiquity , developing from the Attic dialect, with admixture of elements especially from Ionic....

 word ἀνωνυμία, anonymia, meaning "without a name
Name
A name is a word or term used for identification. Names can identify a class or category of things, or a single thing, either uniquely, or within a given context. A personal name identifies a specific unique and identifiable individual person, and may or may not include a middle name...

" or "namelessness". In colloquial use, anonymity typically refers to the state of an individual's personal identity, or personally identifiable information
Personally identifiable information
Personally Identifiable Information , as used in information security, is information that can be used to uniquely identify, contact, or locate a single person or can be used with other sources to uniquely identify a single individual...

, being publicly unknown.

There are many reasons why a person might choose to obscure their identity and become anonymous. Several of these reasons are legal, legitimate and socially approved of—many acts of charity
Charity (virtue)
In Christian theology charity, or love , means an unlimited loving-kindness toward all others.The term should not be confused with the more restricted modern use of the word charity to mean benevolent giving.- Caritas: altruistic love :...

 are performed anonymously, as benefactors do not wish, for whatever reason, to be acknowledged for their action. Someone who feels threatened by someone else might attempt to hide from the threat behind various means of anonymity, a witness to a crime can seek to avoid retribution, for example, by anonymously calling a crime tipline. There are also many illegal reasons to hide behind anonymity. Criminals typically try to keep themselves anonymous either to conceal the fact that a crime has been committed or to avoid capture. Anonymity may also be created unintentionally, through the loss of identifying information due to the passage of time or a destructive event.

The term "anonymous message" typically refers to a message
Message
A message in its most general meaning is an object of communication. It is a vessel which provides information. Yet, it can also be this information. Therefore, its meaning is dependent upon the context in which it is used; the term may apply to both the information and its form...

 (which is, for example, transmitted over some form of a network) that does not carry any information about its sender and its intended recipient. It is therefore unclear if multiple such messages have been sent by the same sender or if they have the same intended recipient.

The problem of determining whether or not the identity of a communication partner is the same as one previously encountered is the problem of authentication
Authentication
Authentication is the act of confirming the truth of an attribute of a datum or entity...

.

In mathematics, in reference to an arbitrary element (e.g. a human, an object, a computer
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...

), within a well-defined set (called the "anonymity set"), "anonymity" of that element refers to the property of that element of not being identifiable within this set. If it is not identifiable, then the element is said to be "anonymous".

Compared with pseudonymity

Sometimes it is desired that a person can establish a long-term relationship (such as a reputation) with some other entity, without necessarily disclosing personally identifying information to that entity. In this case, it may be useful for the person to establish a unique identifier, called a pseudonym
Pseudonym
A pseudonym is a name that a person assumes for a particular purpose and that differs from his or her original orthonym...

, with the other entity. Examples of pseudonyms are pen name
Pen name
A pen name, nom de plume, or literary double, is a pseudonym adopted by an author. A pen name may be used to make the author's name more distinctive, to disguise his or her gender, to distance an author from some or all of his or her works, to protect the author from retribution for his or her...

s, nicknames, credit card numbers, student numbers, bank account numbers, and IP addresses. A pseudonym enables the other entity to link different messages from the same person and, thereby, the maintenance of a long-term relationship.

Someone using a pseudonym would be strictly considered to be using "pseudonymity" not "anonymity", but sometimes the term "anonymity" is used to refer to both (in general, a situation where the legal identity of the person is disguised).

Means of obtaining anonymity

Anonymity is a result of not having identifying characteristics (such as a name or description of physical appearance) disclosed. This can occur from a lack of interest in learning the nature of such characteristics, or through intentional efforts to hide these characteristics. An example of the former would include a brief encounter with a stranger, when learning the other person's name is not deemed necessary. An example of the latter would include someone hiding behind clothing that covers identifying features like hair color, scars, or tattoos, in order to avoid identification.

In some cases, anonymity is reached unintentionally, as is often the case with victims of crime
Crime
Crime is the breach of rules or laws for which some governing authority can ultimately prescribe a conviction...

s or war
War
War is a state of organized, armed, and often prolonged conflict carried on between states, nations, or other parties typified by extreme aggression, social disruption, and usually high mortality. War should be understood as an actual, intentional and widespread armed conflict between political...

 battles, when a body is discovered in such a state that the physical features used to identify someone are no longer present. Anonymity is not always found in such morbid situations, however. As an example, a winner of a lottery
Lottery
A lottery is a form of gambling which involves the drawing of lots for a prize.Lottery is outlawed by some governments, while others endorse it to the extent of organizing a national or state lottery. It is common to find some degree of regulation of lottery by governments...

 jackpot is anonymous (one of however many play the lottery) until that person turns in the winning lottery ticket.

Anonymity may also be created through a gradual eroding of ownership information, such as the passage of time and loss of attribution to a saying.

Anonymity and social situations

Anonymity may reduce the accountability
Accountability
Accountability is a concept in ethics and governance with several meanings. It is often used synonymously with such concepts as responsibility, answerability, blameworthiness, liability, and other terms associated with the expectation of account-giving...

 one perceives to have for their actions, and removes the impact these actions might otherwise have on their reputation
Reputation
Reputation of a social entity is an opinion about that entity, typically a result of social evaluation on a set of criteria...

. This can have dramatic effects, both useful and harmful.

In conversational settings, anonymity may allow people to reveal personal history and feelings without fear of later embarrassment. Electronic conversational media can provide physical isolation, in addition to anonymity. This prevents physical retaliation for remarks, and prevents negative or taboo behavior or discussion from tarnishing the reputation of the speaker. This can be beneficial when discussing very private matters, or taboo subjects or expressing views or revealing facts that may put someone in physical, financial, or legal danger (such as illegal
Law
Law is a system of rules and guidelines which are enforced through social institutions to govern behavior, wherever possible. It shapes politics, economics and society in numerous ways and serves as a social mediator of relations between people. Contract law regulates everything from buying a bus...

 activity, or unpopular, or outlawed political views).

With few perceived negative consequences, anonymous or semi-anonymous forums often provide a soapbox for disruptive conversational behavior. The term Internet troll is sometimes used to refer to those who do this online.

Relative anonymity is often enjoyed in large crowds. Different people have different psychological and philosophical reactions to this development, especially as a modern phenomenon. This anonymity is an important factor in crowd psychology
Crowd psychology
Crowd psychology is a branch of social psychology. Ordinary people can typically gain direct power by acting collectively. Historically, because large groups of people have been able to bring about dramatic and sudden social change in a manner that bypasses established due process, they have also...

, and behavior in situations such as a riot
Riot
A riot is a form of civil disorder characterized often by what is thought of as disorganized groups lashing out in a sudden and intense rash of violence against authority, property or people. While individuals may attempt to lead or control a riot, riots are thought to be typically chaotic and...

. This perceived anonymity can be compromised by technologies such as photography
Photography
Photography is the art, science and practice of creating durable images by recording light or other electromagnetic radiation, either electronically by means of an image sensor or chemically by means of a light-sensitive material such as photographic film...

.

Anonymity, commerce and crime

Anonymous commercial transactions can protect the privacy of consumers. Some consumers prefer to use cash when buying everyday goods (like groceries or tools), to prevent sellers from aggregating information or soliciting them in the future. Credit cards are linked to a person's name, and can be used to discover other information, such as postal address, phone number, etc. The ecash
Ecash
Using cryptography, ecash was introduced by David Chaum as an anonymous electronic cash system. He used blind signatures to achieve unlinkability between withdrawal and spend transactions. Depending on the properties of the payment transactions, one distinguishes between on-line and off-line...

 system was developed to allow secure anonymous transactions. When purchasing taboo goods and services, anonymity makes many potential consumers more comfortable with or more willing to engage in the transaction. Many loyalty program
Loyalty program
Loyalty programs are structured marketing efforts that reward, and therefore encourage, loyal buying behavior — behavior which is potentially beneficial to the firm....

s use cards that personally identify the consumer engaging in each transaction (possibly for later solicitation, or for redemption or security purposes), or that act as a numerical pseudonym
Pseudonym
A pseudonym is a name that a person assumes for a particular purpose and that differs from his or her original orthonym...

, for use in data mining
Data mining
Data mining , a relatively young and interdisciplinary field of computer science is the process of discovering new patterns from large data sets involving methods at the intersection of artificial intelligence, machine learning, statistics and database systems...

.

Anonymity can also be used as a protection against legal prosecution. For example, when committing a robbery, many criminals will obscure their faces to avoid identification. In organized crime
Organized crime
Organized crime or criminal organizations are transnational, national, or local groupings of highly centralized enterprises run by criminals for the purpose of engaging in illegal activity, most commonly for monetary profit. Some criminal organizations, such as terrorist organizations, are...

, groups of criminals may collaborate on a certain project without revealing to each other their names or other personally identifiable information. The movie The Thomas Crown Affair
The Thomas Crown Affair (1968 film)
The Thomas Crown Affair is a 1968 film by Norman Jewison starring Steve McQueen and Faye Dunaway. It was nominated for two Academy Awards and won the Award for Best Song with Michel Legrand's "Windmills of Your Mind"...

depicted a fictional collaboration by people who had never previously met and did not know who had recruited them. The anonymous purchase of a gun or knife to be used in a crime helps prevent linking an abandoned weapon to the identity of the perpetrator.

Anonymity in charity

There are two aspects, one, giving to a large charitable organization obscures the beneficiary of a donation from the benefactor, the other is giving anonymously to obscure the benefactor both from the beneficiary and from everyone else. There are many reasons this is done. Anonymous charity has long been a widespread and durable moral precept of many ethical and religious systems, as well as being in practice a widespread human activity. A benefactor may not wish to establish any relationship with the beneficiary, particularly if the beneficiary is perceived as being unsavory. Benefactors may not wish to identify themselves as capable of giving. A benefactor may wish to improve the world, as long as no one knows who did it, out of modesty, wishing to avoid publicity.

Issues facing the anonymous

Attempts at anonymity are not always met with support from society
Society
A society, or a human society, is a group of people related to each other through persistent relations, or a large social grouping sharing the same geographical or virtual territory, subject to the same political authority and dominant cultural expectations...

. There is a trend in society to mistrust someone who makes an effort to maintain their anonymity. This is often summed up in the statement, "You wouldn't want to stay anonymous unless you had something to hide." The implication is that there is no legitimate reason to obscure one's identity from the world as a whole.

Anonymity sometimes clashes with the policies and procedures of governments or private organizations. In the United States, disclosure of identity is required to be able to vote, though the secret ballot
Secret ballot
The secret ballot is a voting method in which a voter's choices in an election or a referendum are anonymous. The key aim is to ensure the voter records a sincere choice by forestalling attempts to influence the voter by intimidation or bribery. The system is one means of achieving the goal of...

 prevents disclosure of how individuals voted. In airport
Airport
An airport is a location where aircraft such as fixed-wing aircraft, helicopters, and blimps take off and land. Aircraft may be stored or maintained at an airport...

s in most countries, passengers are not allowed to board flights unless they have identified themselves to some sort of airline or transportation security personnel, typically in the form of the presentation of an identification card.

On the other hand, some policies and procedures require anonymity.

Referring to the anonymous

When it is necessary to refer to someone who is anonymous, it is typically necessary to create a type of pseudo-identification for that person. In literature, the most common way to state that the identity of an author is unknown is to refer to them as simply "Anonymous." This is usually the case with older texts in which the author is long dead and unable to claim authorship of a work. When the work claims to be that of some famous author the pseudonym
Pseudonym
A pseudonym is a name that a person assumes for a particular purpose and that differs from his or her original orthonym...

ous author is identified as "Pseudo-", as in Pseudo-Dionysius the Areopagite
Pseudo-Dionysius the Areopagite
Pseudo-Dionysius the Areopagite, also known as Pseudo-Denys, was a Christian theologian and philosopher of the late 5th to early 6th century, the author of the Corpus Areopagiticum . The author is identified as "Dionysos" in the corpus, which later incorrectly came to be attributed to Dionysius...

, an author claiming—and long believed—to be Dionysius the Areopagite
Dionysius the Areopagite
Dionysius the Areopagite was a judge of the Areopagus who, as related in the Acts of the Apostles, , was converted to Christianity by the preaching of the Apostle Paul during the Areopagus sermon...

, an early Christian convert.

Anonymus, in its Latin spelling, generally with a specific city designation, is traditionally used by scholars in the humanities to refer to an ancient writer whose name is not known, or to a manuscript of their work. Many such writers have left valuable historical or literary records: an incomplete list of such Anonymi is at Anonymus
Anonymus
Anonymus is the Latin spelling of anonymous. This Latin spelling, however, is traditionally used by scholars in the humanities to refer to any ancient writer whose name is not known, or to a manuscript of their work...

.

In the history of art, many painting workshops can be identified by their characteristic style and discussed and the workshop's output set in chronological order. Sometimes archival research later identifies the name, as when the "Master of Flémalle"—defined by three paintings in the Städelsches Kunstinstitut in Frankfurt— was identified as Robert Campin
Robert Campin
Robert Campin , now usually identified as the artist known as the Master of Flémalle, is usually considered the first great master of Early Netherlandish painting...

. The 20th-century art historian Bernard Berenson
Bernard Berenson
Bernard Berenson was an American art historian specializing in the Renaissance. He was a major figure in pioneering art attribution and therefore establishing the market for paintings by the "Old Masters".-Personal life:...

 methodically identified numerous early Renaissance Florentine and Sienese workshops under such sobriquet
Sobriquet
A sobriquet is a nickname, sometimes assumed, but often given by another. It is usually a familiar name, distinct from a pseudonym assumed as a disguise, but a nickname which is familiar enough such that it can be used in place of a real name without the need of explanation...

s as "Amico di Sandro" for an anonymous painter in the immediate circle of Sandro Botticelli
Sandro Botticelli
Alessandro di Mariano di Vanni Filipepi, better known as Sandro Botticelli was an Italian painter of the Early Renaissance...

.

In legal cases, a popularly accepted name to use when it is determined that an individual needs to maintain anonymity is "John Doe
John Doe
The name "John Doe" is used as a placeholder name in a legal action, case or discussion for a male party, whose true identity is unknown or must be withheld for legal reasons. The name is also used to refer to a male corpse or hospital patient whose identity is unknown...

". This name is often modified to "Jane Doe" when the anonymity-seeker is female. The same names are also commonly used when the identification of a dead person is not known. The semi-acronym Unsub is used as law enforcement slang for "Unknown Subject of an Investigation".

The military
Military
A military is an organization authorized by its greater society to use lethal force, usually including use of weapons, in defending its country by combating actual or perceived threats. The military may have additional functions of use to its greater society, such as advancing a political agenda e.g...

 often feels a need to honor the remains of soldiers for whom identification is impossible. In many countries, such a memorial is named the Tomb of the Unknown Soldier
Tomb of the Unknown Soldier
Tomb of the Unknown Soldier refers to a grave in which the unidentifiable remains of a soldier are interred. Such tombs can be found in many nations and are usually high-profile national monuments. Throughout history, many soldiers have died in wars without their remains being identified...

.

Anonymity and the press

Most modern newspapers and magazines attribute their articles to individual editors, or to news agencies
News agency
A news agency is an organization of journalists established to supply news reports to news organizations: newspapers, magazines, and radio and television broadcasters. Such an agency may also be referred to as a wire service, newswire or news service.-History:The oldest news agency is Agence...

. An exception is the British weekly The Economist
The Economist
The Economist is an English-language weekly news and international affairs publication owned by The Economist Newspaper Ltd. and edited in offices in the City of Westminster, London, England. Continuous publication began under founder James Wilson in September 1843...

, which may be the world's only un-byline
Byline
The byline on a newspaper or magazine article gives the name, and often the position, of the writer of the article. Bylines are traditionally placed between the headline and the text of the article, although some magazines place bylines at the bottom of the page, to leave more room for graphical...

d paper. All British newspapers run their leaders (i.e. editorials) anonymously.

Anonymity on the Internet



Most commentary on the Internet is essentially done anonymously, using unidentifiable pseudonyms. While these names can take on an identity of their own, they are frequently separated from and anonymous from the actual author, and according to the University of Stockholm creating more freedom of expression, and less accountability. The online encyclopedia Wikipedia
Wikipedia
Wikipedia is a free, web-based, collaborative, multilingual encyclopedia project supported by the non-profit Wikimedia Foundation. Its 20 million articles have been written collaboratively by volunteers around the world. Almost all of its articles can be edited by anyone with access to the site,...

 is collaboratively written mostly by authors using either unidentifiable pseudonyms or IP address identifiers, although a few have used identified pseudonyms or their real names.

Full anonymity on the Internet, however, is not guaranteed since IP addresses, in principle, can be tracked, allowing to identify the computer from which a certain post was made, albeit not the actual user. Anonymizing services such as I2P - The Anonymous Network
I2P
I2P is a mixed-license, free and open source project building an anonymous network .The network is a simple layer that applications can use to anonymously and securely send...

 or Tor
Tor (anonymity network)
Tor is a system intended to enable online anonymity. Tor client software routes Internet traffic through a worldwide volunteer network of servers in order to conceal a user's location or usage from someone conducting network surveillance or traffic analysis...

 address the issue of IP tracking. Their distributed technology approach may grant a higher degree of security than centralized anonymizing services where a central point exists that could disclose one's identity.

Sites such as Chatroulette
Chatroulette
Chatroulette is a website that pairs strangers from around the world together for webcam-based conversations. Visitors to the website begin an online chat with another visitor who is chosen at random...

 and Omegle
Omegle
Omegle is an online chat website that allows users to communicate with strangers without registering. The service randomly pairs users up into one-on-one chat sessions where they chat anonymously using the handles "You" and "Stranger"...

 capitalize on the current fascination with anonymity. They are examples of anonymous chat or stranger chat. Other sites, however, including Facebook
Facebook
Facebook is a social networking service and website launched in February 2004, operated and privately owned by Facebook, Inc. , Facebook has more than 800 million active users. Users must register before using the site, after which they may create a personal profile, add other users as...

 and Google+
Google+
Google+ is a social networking and identity service, operated by Google Inc.The service was launched on June 28, 2011, in an invite-only "field testing" phase. The following day, existing users were allowed to invite friends who were over 18 years of age to the service to create their own accounts....

, require users to sign in with their legal names. In the case of Google+, this requirement has led to a controversy known as the nymwars
Nymwars
Nymwars is the name given to the conflicts over policies mandating that users of internet service identify using real names. They began in July 2011 when the social networking site Google+ began enforcing its real name only policy by suspending the accounts of users it felt were not following the...

.

Anonymity and politics

The history of anonymous expression in political dissent is both long and with important effect, as in the Letters of Junius or Voltaire
Voltaire
François-Marie Arouet , better known by the pen name Voltaire , was a French Enlightenment writer, historian and philosopher famous for his wit and for his advocacy of civil liberties, including freedom of religion, free trade and separation of church and state...

's Candide
Candide
Candide, ou l'Optimisme is a French satire first published in 1759 by Voltaire, a philosopher of the Age of Enlightenment. The novella has been widely translated, with English versions titled Candide: or, All for the Best ; Candide: or, The Optimist ; and Candide: or, Optimism...

, or scurrilous as in pasquinade
Pasquinade
Pasquino or Pasquin is the name used by Romans to describe a battered Hellenistic-style statue dating to the 3rd century BC, which was unearthed in the Parione district of Rome in the 15th century...

s. In the tradition of anonymous British political criticism, the Federalist Papers
Federalist Papers
The Federalist Papers are a series of 85 articles or essays promoting the ratification of the United States Constitution. Seventy-seven of the essays were published serially in The Independent Journal and The New York Packet between October 1787 and August 1788...

  were anonymously authored. Without the public discourse on the controversial contents of the U.S. Constitution, ratification would likely have taken much longer as individuals worked through the issues. The United States Declaration of Independence
United States Declaration of Independence
The Declaration of Independence was a statement adopted by the Continental Congress on July 4, 1776, which announced that the thirteen American colonies then at war with Great Britain regarded themselves as independent states, and no longer a part of the British Empire. John Adams put forth a...

, however, was not anonymous. If it had been unsigned, it might well have been less effective. John Perry Barlow
John Perry Barlow
John Perry Barlow is an American poet and essayist, a retired Wyoming cattle rancher, and a cyberlibertarian political activist who has been associated with both the Democratic and Republican parties. He is also a former lyricist for the Grateful Dead and a founding member of the Electronic...

, Joichi Ito, and other US blog
Blog
A blog is a type of website or part of a website supposed to be updated with new content from time to time. Blogs are usually maintained by an individual with regular entries of commentary, descriptions of events, or other material such as graphics or video. Entries are commonly displayed in...

gers express a very strong support for anonymous editing as one of the basic requirements of open politics as conducted on the Internet. Saipansucks.com is an example of an anonymously written website that socially and politically criticizes the United States' Commonwealth of the Northern Mariana Islands, and UticaSux.com politically criticizes the local government of Utica, New York
Utica, New York
Utica is a city in and the county seat of Oneida County, New York, United States. The population was 62,235 at the 2010 census, an increase of 2.6% from the 2000 census....

, in the United States.

Anonymity and pseudonymity in art

Anonymity is directly related to the concept of obscurantism
Obscurantism
Obscurantism is the practice of deliberately preventing the facts or the full details of some matter from becoming known. There are two, common, historical and intellectual, denotations: 1) restricting knowledge—opposition to the spread of knowledge, a policy of withholding knowledge from the...

 or pseudonymity
Pseudonymity
Pseudonymity is a word derived from pseudonym, meaning 'false name', and anonymity, meaning unknown or undeclared source, describing a state of disguised identity. The pseudonym identifies a holder, that is, one or more human beings who possess but do not disclose their true names...

, where an artist or group attempts to remain anonymous, for various reasons, not limited to: adding an element of mystique to themselves and/or their work, attempting to avoid what is known as the "cult of personality
Cult of personality
A cult of personality arises when an individual uses mass media, propaganda, or other methods, to create an idealized and heroic public image, often through unquestioning flattery and praise. Cults of personality are usually associated with dictatorships...

" or hero worship
Apotheosis
Apotheosis is the glorification of a subject to divine level. The term has meanings in theology, where it refers to a belief, and in art, where it refers to a genre.In theology, the term apotheosis refers to the idea that an individual has been raised to godlike stature...

, where the charisma
Charisma
The term charisma has two senses: 1) compelling attractiveness or charm that can inspire devotion in others, 2) a divinely conferred power or talent. For some theological usages the term is rendered charism, with a meaning the same as sense 2...

, good looks, wealth and/or other unrelated or mildly related aspects of the person(s) is the main reason for interest in their work, rather than the work itself; also the ability to break into a field or area of interest normally dominated by males, such as James Tiptree, Jr
James Tiptree, Jr
James Tiptree, Jr. was the pen name of American science fiction author Alice Bradley Sheldon, used from 1967 to her death. She also occasionally wrote under the pseudonym Raccoona Sheldon...

, the famous science fiction
Science fiction
Science fiction is a genre of fiction dealing with imaginary but more or less plausible content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities...

 author who was actually a woman named Alice Bradley Sheldon, as seems to also be the case with JT LeRoy
JT LeRoy
Jeremiah "Terminator" LeRoy was a pseudonym created by American writer Laura Albert. The name was used from 1996 on for publication in magazines such as Nerve and Shout NY. After his first novel Sarah was published, "LeRoy" started making public appearances...

. The reasons for choosing this approach vary. Some, such as Thomas Pynchon
Thomas Pynchon
Thomas Ruggles Pynchon, Jr. is an American novelist. For his most praised novel, Gravity's Rainbow, Pynchon received the National Book Award, and is regularly cited as a contender for the Nobel Prize in Literature...

, and J. D. Salinger
J. D. Salinger
Jerome David Salinger was an American author, best known for his 1951 novel The Catcher in the Rye, as well as his reclusive nature. His last original published work was in 1965; he gave his last interview in 1980....

 who seem to want to avoid the "limelight" of popularity or simply want to live private lives. Some others include The Residents
The Residents
The Residents is an American art collective best known for avant-garde music and multimedia works. The first official release under the name of The Residents was in 1972, and the group has since released over sixty albums, numerous music videos and short films, three CD-ROM projects and ten DVDs....

, and until 2004, musician Jandek
Jandek
Jandek is the musical project of an anonymous outsider musician who operates out of Houston, Texas. Since 1978, Jandek has self-released over 60 albums of unusual, often emotionally dissolute folk and blues songs without ever granting more than the occasional interview or providing any biographical...

.

This is frequently applied in fiction, from The Lone Ranger
The Lone Ranger
The Lone Ranger is a fictional masked Texas Ranger who, with his Native American companion Tonto, fights injustice in the American Old West. The character has become an enduring icon of American culture....

, Superman
Superman
Superman is a fictional comic book superhero appearing in publications by DC Comics, widely considered to be an American cultural icon. Created by American writer Jerry Siegel and Canadian-born American artist Joe Shuster in 1932 while both were living in Cleveland, Ohio, and sold to Detective...

, and Batman
Batman
Batman is a fictional character created by the artist Bob Kane and writer Bill Finger. A comic book superhero, Batman first appeared in Detective Comics #27 , and since then has appeared primarily in publications by DC Comics...

, where a hidden identity is assumed.

Mathematics of anonymity

An example: Suppose that only Alice, Bob, and Carol
Alice and Bob
The names Alice and Bob are commonly used placeholder names for archetypal characters in fields such as cryptography and physics. The names are used for convenience; for example, "Alice sends a message to Bob encrypted with his public key" is easier to follow than "Party A sends a message to Party...

 have the keys to a bank safe and that, one day, the contents of the safe are missing (without the lock being violated). Without any additional information, we do not know for sure whether it was Alice, Bob or Carol who opened the safe; the perpetrator remains anonymous. In particular, each of the elements in {Alice, Bob, Carol} has a 1/3 chance of being the perpetrator. However, as long as none of them has been identified as being the perpetrator with 100% certainty, we can say that the perpetrator remains anonymous.

Anonymity is not an absolute. That is, the degree of anonymity one enjoys may vary. In the above example, if Carol has an ironclad alibi at the time of the perpetration, then we may deduce that it must have been either Alice or Bob who opened the safe. That is, the probability of the elements {Alice, Bob, Carol} of being the perpetrator is now 1/2, 1/2, and 0, respectively. This clearly amounts to a reduction of the perpetrator's anonymity (i.e., although the perpetrator still remains anonymous, it is now more likely than before that (s)he is either Alice or Bob).

See also

  • I2P
    I2P
    I2P is a mixed-license, free and open source project building an anonymous network .The network is a simple layer that applications can use to anonymously and securely send...

  • Anonymity application
    Anonymity application
    An anonymity application is any software application which can be used to access a network, such as the Internet, anonymously. The application can use either private or public anonymous proxy servers, encryption or even spoofing, diversion and obfuscation to ensure an anonymous and/or difficultly...

  • Anonymous web browsing
    Anonymous web browsing
    Anonymous web browsing is browsing the World Wide Web while hiding the user's IP address and any other personally identifiable information from the websites that one is visiting.-Achieving Anonymity:...

  • List of anonymously published works
  • Anonymous P2P
    Anonymous P2P
    An anonymous P2P communication system is a peer-to-peer distributed application in which the nodes or participants are anonymous or pseudonymous...

  • Friend-to-friend
    Friend-to-friend
    A friend-to-friend computer network is a type of peer-to-peer network in which users only make direct connections with people they know. Passwords or digital signatures can be used for authentication....

  • Private P2P
    Private P2P
    Private peer-to-peer systems are peer-to-peer systems that allow only mutually trusted peers to participate. This can be achieved by using a central server such as a Direct Connect hub to authenticate clients. Alternatively, users can exchange passwords or cryptographic keys with friends to form...

  • Personally identifiable information
    Personally identifiable information
    Personally Identifiable Information , as used in information security, is information that can be used to uniquely identify, contact, or locate a single person or can be used with other sources to uniquely identify a single individual...

  • Pseudonymity
    Pseudonymity
    Pseudonymity is a word derived from pseudonym, meaning 'false name', and anonymity, meaning unknown or undeclared source, describing a state of disguised identity. The pseudonym identifies a holder, that is, one or more human beings who possess but do not disclose their true names...

    , Pseudonymization
    Pseudonymization
    Pseudonymisation is a procedure by which the most identifying fields within a data record are replaced by one or more artificial identifier's. There can be a single pseudonym for a collection of replaced fields or a pseudonym per replaced field. The purpose is to render the data record less...

  • John Doe
    John Doe
    The name "John Doe" is used as a placeholder name in a legal action, case or discussion for a male party, whose true identity is unknown or must be withheld for legal reasons. The name is also used to refer to a male corpse or hospital patient whose identity is unknown...

  • Crypto-anarchism
    Crypto-anarchism
    Crypto-anarchism expounds the use of strong public-key cryptography to bring about privacy and freedom. It was described by Vernor Vinge as a cyberspatial realization of anarchism. Crypto-anarchists aim to create cryptographic software that can be used to evade prosecution and harassment while...

  • Internet privacy
    Internet privacy
    Internet privacy involves the right or mandate of personal privacy concerning the storing, repurposing, providing to third-parties, and displaying of information pertaining to oneself via the Internet. Privacy can entail both Personally Identifying Information or non-PII information such as a...

  • Privacy software
    Privacy software
    Privacy software is software built to protect the privacy of its users. The software typically works in conjunction with Internet usage to control or limit the amount of information made available to third-parties. The software can apply encryption or filtering of various kinds.Privacy software can...

  • FLAIM
    FLAIM
    FLAIM is a modular tool designed to allow computer and network log sharing through application of complex data sanitization policies....

  • Anonymous (group)
    Anonymous (group)
    Anonymous is an international hacking group, spread through the Internet, initiating active civil disobedience, while attempting to maintain anonymity. Originating in 2003 on the imageboard 4chan, the term refers to the concept of many online community users simultaneously existing as an anarchic,...

  • Java Anon Proxy
    Java Anon Proxy
    Java Anon Proxy, also known as JAP or JonDonym, is a proxy system designed to allow browsing the Web with revocable pseudonymity. It was originally developed as part of a project of the Technische Universität Dresden, the Universität Regensburg and Privacy Commissioner of Schleswig-Holstein...

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