Bitcoin
| Bitcoin | |
|---|---|
A common logo from the Bitcoin reference client
|
|
| Date of introduction | 3 January 2009 |
| User(s) | International |
| Money Supply | 25 bitcoins per block (approximately every ten minutes).[1] |
| Source | Number of bitcoins in circulation |
| Subunit | |
| 10−8 | Satoshi[2] |
| Symbol | BTC, XBT,[3]  ,฿[4][note 1] |
Bitcoin is a peer-to-peer payment
system and digital currency introduced as open
source software in 2009 by pseudonymous developer Satoshi
Nakamoto. It is a cryptocurrency, so-called because it uses cryptographyto
control the creation and transfer of money.[5] Users
send payments by broadcasting digitally signed messages to the network.
Participants known as miners verify and timestamp transactions
into a shared public databasecalled the block chain, for which they are rewarded with transaction fees and newly minted bitcoins.[6] Conventionally
"Bitcoin" capitalized refers to the technology and network whereas "bitcoins" lowercase refers to the currency itself.[7] Bitcoins
can be obtained by mining or in exchange for products, services, or other currencies.[8]
Bitcoin has been a subject of scrutiny due to ties with illicit activity. In 2013 the FBI shut
down the Silk Road online black
market and seized 144,000 bitcoins worth US$28.5 million at the time.[9] The
United States, however, is currently considered to be Bitcoin friendly compared to other governments.[10] In China,
new rules restricted bitcoin exchange for local currency,[11] and
the European Banking Authority has warned that Bitcoin lacks consumer protections.[12] Bitcoins
can be stolen, and chargebacksare impossible.[13]
Commercial use of Bitcoin, illicit or otherwise, is currently small compared to its use by speculators,
which has fueled price volatility.[14] Bitcoin
as a form of payment for products and services has seen growth, however, and merchants have an incentive to accept the currency because transaction fees are
lower than the 2–3% typically imposed by credit card processors.[15]
Transactions
Users send and receive payments using client
software on a personal computer, mobile
device or web application. Transactions do not explicitly identify the payer and payee by name. Instead,
a Bitcoin transaction transfers ownership from one Bitcoin address to another. Approximately every ten minutes, a block of transactions is confirmed to a shared public record called the block chain. This competitive confirmation process known as mining carries
a reward of 25 bitcoins per block.[16]
Software
Bitcoin client software, or simply Bitcoin clients, allow a user to send and receive bitcoin transactions. The first Bitcoin software was released in 2009 by Satoshi Nakamoto as open
source code. The "Satoshi client", Bitcoin-Qt, has since been maintained and enhanced by a group of core developers and other contributors. Bitcoin-Qt can be used as a desktop client for regular payments or as a server utility for merchants and other payment
services. Historically Bitcoin-Qt also supported bitcoin mining, however this feature has been redacted due to the relative inefficiency of performing mining computations on a CPU.
Bitcoin-Qt is sometimes referred to as the "reference client" because it serves to define the Bitcoin protocol and acts as a reference standard for other implementations.
Bitcoin clients have been implemented in several programming languages for personal computers, mobile devices, and as web applications. At the most basic a client generates and stores private
keys and communicates with peers on the Bitcoin network. When making a purchase with a mobile device, the use of QR codes to
simplify transactions is ubiquitous. There are also now several server software implementations of the
Bitcoin protocol.[citation
needed] So-called "full client" nodes on the network validate transactions and blocks they receive and relay them to connected peers.
Wallets
Bitcoin uses the ECDSA implementation of public-key
cryptography, in which pairs of cryptographic keys, one public and one private, are generated.[18] A
collection of keys is called awallet. Note that sometimes the term wallet is used to mean client software in the sense ofdigital
wallet. A Bitcoin transaction transfers ownership to a new address, an alphanumeric string of the form 1FfmbHfnpaZjKFvyi1okTjJJusN455paPH derived from public keys by application of a hash
function andencoding scheme. The corresponding private keys act as a safeguard; a valid
payment message from an address must contain the associated public key and a digital signature proving possession of the associated private key. Because anyone with a private key can spend all of the bitcoins sent to the corresponding address, the essence
of Bitcoin security is protection of private keys.
Theft of bitcoins has occurred on numerous occasions.[19] The
practical day-to-day security of Bitcoin wallets remains an on-going concern.[20] Risk
of theft can be reduced by generating keys offline on an uncompromised computerand saving them on external
storage or paper printouts.[21]
Various vendors produce physical bitcoins, collectables that store a private key on paper, metal,[22] wood,[23] or
plastic. Images of physical bitcoins are ubiquitous in media coverage of Bitcoin.
Block chain
Integral to Bitcoin is a public database and sequential record of all transactions, known as the block chain, that records current bitcoin ownership as well as at all points in the past. By
keeping a record of all transactions, the block chain prevents double-spending.[16] Those
that maintain the block chain are called miners and are rewarded with newly created bitcoins as well as transaction fees. Payment processing work done by miners verifies each transaction as valid and adds it to the block chain.[24] Bitcoin
payment processing fees are optional and generally substantially lower than those of credit cards or money transfers.[25] Currently,
doing the work of payment processing is rewarded with newly created bitcoins, 25 per block. The block reward will be halved to 12.5 bitcoins in 2017 and again approximately every four years thereafter. By 2140 there will be approximately 21 million bitcoins
in existence and transaction processing will be solely incentivized by transaction fees.[26] Today,
transactions that pay a fee may be processed more quickly.[citation
needed]
Exchanges
![[icon]](http://en.wikipedia.org/wiki/File:Wiki_letter_w_cropped.svg){kind=small} |
This section requires expansion.(December 2013) |
Through various exchanges,
bitcoins are bought and sold at a variable price against the value of other currencies.[27] While
there may be a seemingly large number, exchanges regularly fail, taking client bitcoins with them.[28] A
published research study showed that of 40 Bitcoin exchange markets studied, 18 ended up closing over a period of 3 years.[19] Bitcoin
prices are fragmented and vary widely across exchanges.[29]
Lack of anonymity
The block chain is a public ledger of every bitcoin transaction and does provide pseudo-anonymity in that a bitcoin address do not directly identify their owner. However, tracking the flow
of bitcoins through transactions can give clues as to who the owner is.[30] Bitcoin
uses cryptography but does not do so to protect the identities of its users. Bitcoin is anonymous in that it is difficult to associate Bitcoin transactions with real-life identities.[31]In
addition Bitcoin intermediaries such as exchanges are required by law in many jurisdictions to collect personal customer data.[32]
History
First mentioned in a 2008 paper published under the pseudonym "Satoshi Nakamoto", Bitcoin became operational in early 2009 with the release of the first open
source Bitcoin client and the issuance of the first bitcoins.[33][34][35] The
currency had early technical problems such as a 2009 exploit that allowed the creation
of unlimited bitcoins.[16]
It is widely believed that the first bitcoin trade for goods or services took place on May 21 2010 when Laszlo Hanyecz, a programmer living in Florida, sent 10,000 bitcoins to a volunteer in
England who ordered two pizzas for Hanyecz at a cost of US$25.[36]
By May 2011 interest in Bitcoin was growing, as were concerns. A report by Jason
Calacanis included statements such as "Bitcoin may be the most dangerous technological project since the internet itself." [37]
The price of bitcoins has fluctuated wildly since its inception, going through various cycles of appreciation, which have been referred to as "Bubbles".[38] In
2011 the value of one bitcoin rapidly rose from about US$0.30 to US$32, reached parity with the USD for the first
time in February 2011[16] before
falling back down to US$2.[39]
Following increased media attention in the latter half of 2012 and the 2012-2013
Cypriot Financial Crisis, the bitcoin price[40] began
to rise again in early 2013 reaching a peak of US$266 on April 10 before crashing to around US$50 [41]
In 2013 some mainstream services began accepting it as a form of payment.[42] Certain non-profit or advocacy groups
also began accepting bitcoins.
2013 also saw the first interventions by law enforcement. Assets belonging to the Mt.Gox exchange
were seized, and the Silk Road drugs trading website was shut down.[43]
During November 2013, the China-based Bitcoin exchange BTC
China overtook Japan-based Mt.Gox and Europe-basedBitstamp to become the largest Bitcoin trading exchange by trade volume.[44] On
19 November 2013, the value a bitcoin on the Mt.Gox exchange soared to a peak of US$900 following a United States Senate committee hearing, at which the committee was informed that virtual currencies were a legitimate financial service.[45] On
the same day, one bitcoin traded for over RMB¥6780 (US$1100) in China.[46] With
roughly 12 million bitcoins in existence as of November 2013,[47] the
new price increased the market cap for Bitcoin to at least US$7.2 billion.[48]
By November 23, 2013 the total market capitalisation of all bitcoins in existence exceeded US$10 billion for the first time.[49]
On 5 December 2013, the People's
Bank of China announced it was prohibiting Chinese financial institutions from using bitcoins.[11] Following
the introduction of these new rules, the value of bitcoin dropped[50] and
Chinese internet giant Baidu reversed its policy of accepting bitcoins for certain services.[51] Starting
in October 2013, Baidu had been allowing clients of website security services to pay with bitcoins.[52] Buying
real-world goods with any virtual currency has been illegal in China since at least 2009.[53]
Economics
Bitcoin's rate of inflation is predefined within the Bitcoin
protocol and is decreasing as time goes on. At some point Bitcoin will become a deflationary currency as no new coins
will be released. Since the rate of inflation is fixed it has been called "inflation-proof", or more specifically resistant to uncontrolled inflation.[54] At
present the exchange price of a bitcoin is extremely volatile, which has led
to some questions about its ability to function as a currency,[55] however
others contend this is a necessary "growing pain" in such a new technology,[56][57] and
that Bitcoin needs to grow to achieve stability.[58]
Bitcoin's eventual deflationary bias, which incentivizes hoarding and removes money from circulation, is also cited as a stumbling block to Bitcoin becoming a functional currency.[59]
Even if Bitcoin doesn't succeed as a currency, it may continue to prove useful as a payment processing system. Volatility has little effect on its utility in this regard since money would need
to be converted to bitcoins only for the short time it takes to make a payment or transfer.[60] Processing
fees are also substantially lower than those of credit cards or money transfers.[25] Some
feel that Bitcoin may be especially well suited to facilitating cheap cross-border money transfers.[60]
Currently Bitcoin does see use as a currency[61] and
by November 2013 there were about 1,000 brick and mortarbusinesses willing to accept payment in bitcoins,[62] and
more than twenty thousand merchants online.[63]
Alternative to national currencies
Some have suggested that Bitcoin is gaining popularity in countries with problem-plagued national currencies, as it can be used to circumvent inflation,
capital controls, and international sanctions. Bitcoins are used by some Argentinians as an alternative to the official currency,[64] which
is stymied by inflation and strict capital controls.[32] In
addition, some Iranians use bitcoins to evade currency sanctions.[65]
Financial journalists and analysts have suggested that there was a link between higher Bitcoin usage in Spain and the 2012-2013
Cypriot financial crisis.[66]
Bubbles
Noted individuals who have named Bitcoin a bubble include Former Federal Reserve Chairman Alan
Greenspan;[67] a core developer
of the Bitcoin protocol, Mike Hearn;[68] and
Economist John Quiggin.[69]
Reuters journalist Felix Salmon correctly predicted the bursting of one such Bitcoin bubble in April 2013.[70]
Nick Colas, a market strategist for ConvergEx Group, is among those who see Bitcoin's quick rise in price as nothing more than normal economic forces at work.[71]
Bitcoin's Lead Developer, and Chief Scientist of the Bitcoin Foundation, Gavin
Andresen has also spoken on the subject stating "I predict there will be between one and five Bitcoin bubbles" [72]
Intrinsic value
Bitcoins have been described as lacking intrinsic
value because their value is not backed by hard assets or the full faith and credit of a sovereign government but
their value depends only on the belief that bitcoins have achieved significant acceptance and lasting permanence. [73][69]
Speculation
Bitcoins are often traded as an investment[74] by
speculators who expect the currency to increase in value as its popularity widens.[75] The
European Banking Authority has warned that the risks of engaging in such speculation go beyond the possibility that the value of Bitcoin drops.[76]
Their vulnerability to hacking and theft also makes their use as an investment more questionable.[77] Velasco
and Medina counter this argument by noting the abstract work involving in minting a bitcoin: while the use value of a bitcoin
is not universally agreed upon, its labour value is firmly established.[78]
Derivatives of
bitcoins are thinly available. One organization offers futures contracts against multiple
currencies.[79]
Bitcoins have attracted the attention of some Wall Street types with Peter
Thiel's Founders Fund investing US$3million
and the Winklevoss twins making a US$1.5 million
personal investment[80] as
well as making an attempt to launch a Bitcoin ETF. On January 7, 2014 it was
reported that the IRS were studying how bitcoins might be taxed.Forbes suggested
that a motivation behind the review may have come as a result of attempts by the Winklevoss twins to create an exchange traded fund.[81]
Reception
Economists have had a mixed reaction to Bitcoin. Some have responded positively to Bitcoin, including François R. Velde, senior economist of the Federal Reserve in Chicago who described it
as "an elegant solution to the problem of creating a digital currency."[82][83]
Other economists commenting on Bitcoin have been critical. Nobel laureatePaul
Krugman has suggested that the structure of the currency incentivizes hoarding and that its value derives only from the expectation that others will accept it as payment [84][85] further
dismissing Bitcoin as being essentially worthless[86] since
it has "no clear use" [87] and commenting
on price volatility stated that "The economic significance of this roller coaster was basically nil".[88]
Former U.S.
Treasury Secretary Larry Summers has expressed a "wait and see" attitude when it comes to Bitcoin.[89] Bitcoin
has been criticized for itsproof of knowledge by the free
software movement activists includingRichard Stallman, who called for reformed development.[90]
In November 2013 Richard Branson announced
that Virgin Galactic would accept Bitcoin as payment, saying that he had invested in Bitcoin and found it "fascinating
how a whole new global currency has been created", encouraging others to also invest in Bitcoin.[91][92] PayPal President David
A. Marcus has said he thinks that Bitcoin is a "great place to put assets" but that it won't be a currency until its price volatility reduces.[93]
Legal issues and status
Criminal activity linked to Bitcoin has largely centered around theft of the currency, the use of botnets for mining, and the fact that some will accept bitcoins in exchange for illegal items
or services. Certain nation states may feel that its use in circumventing capital controls and for gambling are also undesirable. While some governments have taken a hands-off approach, others have moved to regulate Bitcoin and similar, private currencies.
This may stem from a perceived association with criminal activity, the ability of Bitcoin to evade capital controls, and the fact that the currency lacks consumer protections.[citation
needed]
Black markets
Several news outlets have asserted that the popularity of Bitcoin hinges on the ability to use them to purchase illegal substances.[94] In
2013 The Guardian reported that the currency was primarily used to purchase illegal drugs and for online
gambling,[95] and The
Huffington Post stated that "online gambling accounts for a huge portion of Bitcoin activity."[96] C. 2013
legitimate transactions were thought to be far less than the number involved in the purchase of drugs,[97] and
roughly one half of all transactions made using Bitcoin were bets placed at a single online gaming website.[98] In
2012, an academic from the Carnegie Mellon CyLab and the Information Networking Institute estimated that 4.5 to 9% of all bitcoins transacted were for purchases of drugs at a single online market, Silk Road.[99] As
the majority of the Bitcoin transactions were at this time speculative in nature, this academic asserted that drugs constituted a much larger percentage of the products and services bought using the currency, however.[99] The
Huffington Post stated in 2013 that online gun dealers use Bitcoin to sell arms without background checks.[100]
Criminal activity
Bitcoin's association with criminal activities has historically hindered the currency from attaining widespread, mainstream use and has attracted the attention of financial regulators, legislative
bodies, and law enforcement.[101]The
Washington Post had labeled it "the currency of choice for seedy online activities,"[102] and CNN has
called Bitcoin a "shady online currency [that is] starting to gain legitimacy in certain parts of the world."[103] Its
links to criminal activities have prompted scrutiny from the FBI, US Senate, and the State of New York. The FBI stated in a 2012 report that "bitcoins will likely continue to attract cyber-criminals who view it as a means to move or steal funds".[104]
Steven Strauss, a Harvard public policy professor, has suggested that due to its close association with illegal purchases, governments could outlaw Bitcoin, which was also mentioned in 2013 SEC filing
made by a Bitcoin investment vehicle.[105] Bitcoins
are not currently illegal in the US, however. FBI Special Agent Christopher Tarbell has stated that "bitcoins are not illegal in and of themselves and have known legitimate uses".[106]
Legal status
Many governments have made announcements regarding Bitcoin, and these decisions also likely affect treatment of othercryptocurrencies as
well.
Some, including Australia, Canada, Finland, and Germany have simply stated that normal earned income rules apply to Bitcoin.[107] Other
states reject the label of currency but will collect taxes on Bitcoin transactions such as Norway.[108] (Germany
may technically fall into this latter category as it refers to Bitcoin as a unit of account,[109] which
is one of several roles fully fledged currencies play.)
Still more have issued statements that assert Bitcoin is not regulated in their jurisdictions, such as Singapore and Poland.[citation
needed] Denmark is among those that, as of 2013, have stated future regulations may be imposed.[108]
In the United States, the Financial
Crimes Enforcement Network has established regulatory guidelines for currencies such as Bitcoin, classifying certain firms engaged in the exchange and mining of Bitcoins as money
services businesses.[110] New
York state has considered the possibility of regulating Bitcoin.[111]
Money laundering
Some regulatory and law enforcement authorities, including the European
Banking Authority, feel Bitcoin may be used for money laundering.[112] A
2012 report by the FBI acknowledged such fears but stated that there were no known instances of this occurring.[104] Some
say one obstacle to bitcoins becoming widely used to launder money is that all transactions are public.[113] During
a US Senate hearing in 2013, Jennifer Shasky Calvery, director of the Treasury Department's Financial Crimes Enforcement Network stated, "cash is probably still the best medium for money laundering."[114]
Unauthorized mining
In June 2011, Symantec warned about the possibility of botnets engaging
in covert mining of bitcoins.[115] Some
malware used the parallel processing capabilities of GPUs built
into many modern video cards.[116] In
mid-August 2011, Bitcoin mining botnets were detected again,[117] and
less than three months later Bitcoin mining trojansinfecting Mac
OS X were also discovered.[118] In
April 2013 electronic sports organization E-Sports Entertainment was accused of hijacking 14,000 computers
to mine bitcoins; the case was settled in November with the organization fined US$1 million if it breaks the law within the following ten years or $325,000 if it does not.[119]
Thefts
Theft of bitcoins has happened on a regular basis. Generating and storing keys offline mitigates such risks, however.[120] In
addition to theft, bitcoins can be lost. One user lost £4.0m when he inadvertently discarded a hard drive storing 7,500 bitcoins.[121]
In late November 2013, as many as 96,000 bitcoins were stolen from the online drug website "Sheep Marketplace".[122]Users
were able to track and trace the theft although the thief made efforts to launder transactions through a process called "tumbling".[123] Although
the coins were successfully traced they have not yet been recovered.[124]