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  Cryptocurrency Miner Maker Coinmine Raises $2.5 Million
User Avatar Forum: Mining
Posted by: Noraldaim - 08-16-2019, 08:09 AM - No Replies

Coinmine, Inc., the creator of the Coinmine One cryptocurrency
mining device, has raised $2.5 million in a funding round led by
Los Angeles-based M13 Ventures with participation from Republic
Labs, Gumi Crypto, Canaan Beta and early Uber investor Shervin
Pishevar, the company’s CEO and co-founder, Farbood Nivi, told Bitcoin Magazine.

The new funding round brings the total amount raised by Coinmine
to $4.5 million. Early backers of the startup include Coinbase Ventures,
Social Leverage, Wonder VC, Arrington Capital and angel investors including
Balaji Srinivasan, co-founder of Earn.com, and Brian Norgard, chief product officer of Tinder.
Launched in November 2018, California-based Coinmine is the make
r of the Coinmine One, a cryptocurrency miner targeted at mainstream users.
The miner has an accompanying mobile app which allows
users to set up, control and keep track of their miner’s activity. 
At launch, the Coinmine One was able to mine monero, zcash, grin
and ether, and in June 2019, the company added the ability for users to
receive payouts in bitcoin. The device doesn’t mine bitcoin directly but
instead algorithmically selects “whatever converts best to bitcoin.
” These bitcoin payouts are calculated based on “current market prices,
” Jinny Kang, head of public relations and partnerships at Coinmine, told Bitcoin Magazine.
Since April 2019, the company has been growing over 50 percent
month-over-month only from word of mouth, Nivi said. He declined
to share specific sales or revenue figures but said that the company
was on track to beat its 2019 sales targets.
Nivi also said that the company will use the capital injection to expand
the cryptocurrencies available through the device, add new services and
ship over-the-air updates with improvements like increased hash power and energy efficiency.

The Coinmine One Cryptocurrency Miner
Coinmine claims its Coinmine One miner is the world’s “first all-in-one crypto
device” made for the average consumer. The device isn’t meant to get users
rich overnight, but rather to help them get started with cryptocurrencies,
and allow them to mine new tokens and run a full node on the network.  
Users don’t need to have any previous experience or expertise with
cryptocurrency mining, and the set up is relatively easy and straightforward:
just plug the miner into a wall outlet, install the mobile app, connect the
Coinmine One to WiFi through the app and select a coin to start mining.
The cryptocurrencies mined are then immediately stored in the in-app digital wallet.
All devices come with a full version of the Bitcoin blockchain and a Lightning Network
Daemon (LND). Nivi said that Lightning functionalities should be turned
on and available later this year with another wireless update.
“You’ll be able to send and receive bitcoin directly from your Coinmine
One — instantly and for free,” he said. “You’ll also help Bitcoin succeed
by helping other people route bitcoin payments through your Coinmine
One and you’ll even earn a little bitcoin for doing that.”
The MineOS Operating System
The Coinmine One miner is powered by a proprietary operating system
called MineOS, which the company started building internally in 2018.
Some of MineOS’s unique features include automated overclocking and
undervolting hardware on the fly, as well as automated updating and upgrading over the air.
Updates so far in 2019 include the reduction of the Coinmine One energy
consumption by 30 percent, the addition of bitcoin payouts, support for
grin mining and the increase of ether hashrate by 5 percent.
Moving forward, Nivi said that Coinmine plans to add support for handshake
(HNS) mining as well as new services and features such as the ability for
users to earn interest on their cryptocurrency.
“There are decentralized finance services like Compound Finance that let
you earn interest on your crypto and you can take your principal out
whenever you want,” he said. “So we can invest the crypto your Coinmine
One is making into a service like that and earn you interest. We plan to launch it this year.”
The post Cryptocurrency Miner Maker Coinmine Raises $2.5 Million appeared first on Bitcoin Magazine.

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Rainbow اسئلة شائعة عن البتكوين
User Avatar Forum: (Arabic) العربية
Posted by: Noraldaim - 08-15-2019, 07:15 AM - No Replies

كل ما تحتاج ان تعرفه عن البتكوين بدون تعقيد
   

نعرض هنا البتكوين لانها اقدم و اشهر عملة اليكترونية (تعريف و يكيبيديا) بيتكوين
(بالإنجليزية: Bitcoin) هي عملة إلكترونية (عُملة تشفيرية) يمكن مقارنتها بالعملات الأخرى
مثل الدولار أو اليورو، لكن مع عدة فوارق أساسية، من أبرزها أن هذه
العملة هي عملة إلكترونية بشكل كامل تتداول عبر الإنترنت فقط من دون
وجود فيزيائي لها. كما أنها تختلف عن العملات التقليدية بعدم وجود هيئة
تنظيمية مركزية تقف خلفها، لكن يمكن استخدامها كأي عملة أخرى للشراء
عبر الإنترنت أو حتى تحويلها إلى العملات التقليدية. (انتهى)

كيف يتم تداولها؟
يتم تداولها مباشرة من شخص لاخر عبر الانترنت (الحاسوب او الهاتف المحمول)
دون وسيط او هيئة مركزية ، و بدون فتح حساب مع اي جهة
ما يحتاجه من يرسل اليك البتكوين
هو عنوان "محفظتك الاليكترونية" .
و يشبه الشكل التالي : 1JqARj6EjN2fGTE2a6tnyeHKRqm2Fyn5zg

و بالمقابل فستحتاج عنوان "محفظة" متلقي البتكوين حين تريد ارسالها ،
و بالطبع الرمز الخاص بك الذي يسمح لك بالتصرف بالبت كوين الخاصة بك.

هل يمكن للطرف الاخر الكشف عن هويتي عبر عملية الارسال او الاستقبال؟
كل ما يعرفه الطرف الاخر هو عنوان محفظتك الاليكترونية ، بدون اسم او عنوان
او اي تفاصيل اخرى. فيما عدا ان الشخص يعرف مسبقا عنوان محفظتك ،
او يراقب معلومات اخرى تخصك ، كرقم نطاق الانترنت الخاص بك، فمن الصعب جدا ان يتعرف اليك

كم هي تكلفة تحويل البتكوين؟
التكلفة تتراوح بين مجانا ، مرورا ببضع سنتات ، الى ما لا يتجاوز نصف دولار ،
مهما كان المبلغ المحول ضخما

هل يمكن تجميد حسابي؟
من المستحيل تكنولوجيا تجميد حساب اي شخص ، لانه ببساطة لا يوجد حساب ليجمد

اذا لم املك حسابا مع اي جهة، كيف اعرف رصيدي؟
البتكوين عبارة عن كشف حساب لكل العمليات ، كل من يشترك في عملية
يتلقى جهازه نسخة محدثة من كشف الحساب و من حركة العمليات يتم
حساب الرصيد و الايداع و السحب.

هل هناك حد للعمليات التي اقوم بها؟
لا حد لتداول البتكوين التي تملكها

هل يمكن ان الغي العملية التي قمت بها؟
عمليات الارسال و الاستقبال نهائية ، و مستحيل تكنولوجيا الغائها. و
لكن بامكان الطرف الذي تلقى الاموال اعادتها اليك.

هل هناك جهة تحكيمية الجأ اليها؟
لا يوجد.

هل عروض الثراء باستثمار البتكوين حقيقية؟
٩٠٪ من تلك العروض وهمية و مجرد عمليات احتيال تحت مسميات عديدة منها مثلا
"التعدين السحابي"، هذا المقال يتخدث عن نسبة الغش في تلك العروض

البتكوين الواحدة سعرها مرتفع جدا، كيف يمكنني شرائها؟
يمكن شراء اجزاء صغيرة جدا من البتكوين تسمى ساتوشي جزء من مئة مليون
0.00000001

كيف استفيد من البتكوين في العالم الواقعي؟
هناك عدد من المحال التجارية و مواقع الانترنت تقبل عملة البتكوين ،
كما ان هناك عدد من البورصات الاليكترونية التي بامكانك تحويل البتكوين
فيها الى عدد من العملات العالمية. و هناك مواقع تحتفظ بقائمة بمن يتعاملون في
بيع و شراء البت كوين في منطقتك للتواصل معهم.

كم من الوقت تستغرقه عملية التحويل؟
عدة دقائق على الاكثر

من هي الجهة التي (تصدرها) ؟
اي شخص بامكانه ان يصدر البتكوين ، فعملية اصدارها تحدث بعملية تسمى (التعدين)
حيث يحاول جهاز الحاسوب الخاص بك ، حل مسائل حسابية معقدة ، تجازى على
حلها بمجموعة من عملة البتكوين . لكن في الواقع المسائل الحسابية تتزايد في التعقيد ،
لذا تستخدم مجموعات برامج ربط حاسباتها في مجهود جماعي لحل تلك المسائل و يقوموا باقتسام البتكوينز التي تم (تعدينها)

هل هي عرضة للتضخم؟
بالرغم من ان قيمة البتكوين تتذبذب باستمرار ، البتكوين مصممة كي يكون هناك
عدد محدود منها يمكن تعدينه ، فبعد ان تصل وحدات البتكوين الى 21 مليون
لا يمكن استمرار التعدين .
و هو ما يجعل هذه العملة تفلت من سياسة الحكومات في طباعة النقد دون ما يقابله من احتياط ،
و التسبب في تدني قيمة العملة الشرائية.
لكن لا ننسى ان البتكوين هي عملة غير مغطاة هي ايضا باي نوع من السلع ،
و قيمتها فقط تعتمد على ما يمكنك الحصول عليه مقابلها ، و قيمة الطلب عليها.

كل ما اسمعه من اخبار عن البتكوين هي اخبار مقلقة، ما الذي يحدث؟
كما بداية كل شئ على الانترنت ، هناك من يتربص بنقاط الضعف في بدايته.
البتكوين لا تكشف هوية مستخدميها و لا تمتلك رقمًا متسلسلًا ولا أي وسيلة أخرى
كانت من أي نوع تتيح تتبع ما تم إنفاقه للوصول إلى البائع أو المشتري، لذا هي رائجة
بين من ينشدون الخصوصية ، و لكن للاسف ايضا بائعي البضاعة غير المشروعة
(مثل المخدرات) عبر الإنترنت على حدٍ سواء.

كما ان تحديث "كشف حساب العمليات" يستغرق بضع دقائق ، مما حدا بالبعض
لاستغلال ذلك الوقت لاجراء عمليات اخرى سريعة ، في حال ان سبقت العملية الاولى الغتها.
و لكن بعد ان تم خداع الطرف الاول بانه استلم البتكوين. و هي عملية
ادت الى افلاس احد اقدم و اهم مواقع تبادل البتكوين و هو
MtGox باليابان. و لكن الان اكثر مواقع تبادل العملات الاليكترونية اضحت تنتظر تأكيد العملية قبل اقرارها.

كما ان الحكومات المستبدة او تلك التي تفرض مراقبة لصيقة على حركة الاموال لا تروق
لها فكرة حرية تنقل الاموال دون رقابة.
و بالاخص حين تفرض الجهات الحكومية سعر مجحف لصرف العملات لا يتناسب
مع سعر العادل للعملة في سوق العملات المفتوح.
بالاضافة الى المؤسسات المالية الضخمة التي يشكل تحول العملات مصدر كبير من دخلها.

كيف يحدد سعر صرف البتكوين؟
هناك عدد من مواقع المضاربة ، و العرض و الطلب يختلف من موقع لاخر ،
لذا ستجد ان الاسعار تختلف قليلا على حسب المصدر.

لماذا تتعرض البت كوين لتقلبات سعرية كبيرة؟
كمعظم السلع و الاستثمارات تتعرض البتكوين للمضاربات ، كما يحدث في كل
العملات و الاسهم و حتى في سوق العقار .

ما هي العملات الاليكترونية الاخرى؟
برنامج البتكوين مفتوح المصدر ، فبامكان الاخرين اصدار عملاتهم الخاصة ،
و هو ما حدث بالفعل ، فاليوم يوجد ما لا يقل عن 200 عملة اليكترونية.
في المرتبة الثانية في الاهمية عملة اللايت كوين ، وعملة الدوج كوين ،
و يمتازوا بسعرهم الزهيد مقارنة بالبت كوين ، و السهولة النوعية في تعدينهم.

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Star What is bitcoin?
User Avatar Forum: Bitcoin Discussion
Posted by: Noraldaim - 08-03-2019, 08:53 AM - No Replies

Bitcoin is an innovative payment network and a new kind of money

   
Bitcoin uses peer-to-peer technology to operate with no central
authority or banks; managing transactions and the issuing of bitcoins is
carried out collectively by the network.
Bitcoin is a cryptocurrency. It is a decentralized digital currency
without a central bank or single administrator that can be sent from
user to user on the peer-to-peer bitcoin network without the need for intermediaries.

Transactions are verified by network nodes through cryptography
and recorded in a public distributed ledger called a blockchain.
Bitcoin was invented by an unknown person or group of people
using the name Satoshi Nakamoto and was released as
open-source software in 2009. Bitcoins are created as a reward for a process
known as mining. They can be exchanged for other currencies,
products, and services.  Research produced by University of Cambridge
estimates that in 2017, there were 2.9 to 5.8 million unique users using
a cryptocurrency wallet, most of them using bitcoin.

Bitcoin has been criticized for its use in illegal transactions, its high electricity
consumption, price volatility, thefts from exchanges, and by reputable
economists stating that "it should have a zero price".  Bitcoin has also been used
as an investment, although several regulatory agencies have issued investor alerts about bitcoin.

Creation

The domain name "bitcoin.org" was registered on 18 August 2008.[22]
On 31 October 2008, a link to a paper authored by Satoshi Nakamoto titled
Bitcoin: A Peer-to-Peer Electronic Cash System[4] was posted to a cryptography
mailing list.[23] Nakamoto implemented the bitcoin software as open-source code
and released it in January 2009.[24][25][16] Nakamoto's identity remains unknown.[15]
On 3 January 2009, the bitcoin network was created when Nakamoto
mined the first block of the chain, known as the genesis block.[26][27] Embedded
in the coinbase of this block was the text "The Times 03/Jan/2009 Chancellor on
brink of second bailout for banks".[16] This note references a headline published
by The Times and has been interpreted as both a timestamp and a comment on
the instability caused by fractional-reserve banking.[28]:18
The receiver of the first bitcoin transaction was cypherpunk Hal Finney,
who had created the first reusable proof-of-work system (RPoW)
in 2004.[29] Finney downloaded the bitcoin software on its release date,
and on 12 January 2009 received ten bitcoins from Nakamoto.[30][31]
Other early cypherpunk supporters were creators of bitcoin predecessors:
Wei Dai, creator of b-money, and Nick Szabo, creator of bit gold.[26]
In 2010, the first known commercial transaction using bitcoin occurred
when programmer Laszlo Hanyecz bought two Papa John's pizzas for ₿10,000.[32]
Blockchain analysts estimate that Nakamoto had mined about one
million bitcoins[33] before disappearing in 2010, when he handed
the network alert key and control of the code repository over to
Gavin Andresen. Andresen later became lead developer at the
Bitcoin Foundation.[34][35] Andresen then sought to decentralize
control. This left opportunity for controversy to develop over the
future development path of bitcoin, in contrast to the perceived authority
of Nakamoto's contributions.[36][35]
2011–2012
After early "proof-of-concept" transactions, the first major users of bitcoin
were black markets, such as Silk Road. During its 30 months of existence,
beginning in February 2011, Silk Road exclusively accepted bitcoins as payment,
transacting 9.9 million in bitcoins, worth about $214 million.[37]:222
In 2011, the price started at $0.30 per bitcoin, growing to $5.27 for the year.
The price rose to $31.50 on 8 June. Within a month the price fell to $11.00.
The next month it fell to $7.80, and in another month to $4.77.[38]
Litecoin, an early bitcoin spin-off or altcoin, appeared in October 2011.[39]
Many altcoins have been created since then.[40]
In 2012, bitcoin prices started at $5.27 growing to $13.30 for the year.
[38] By 9 January the price had risen to $7.38, but then crashed by 49%
to $3.80 over the next 16 days. The price then rose to $16.41 on 17
August, but fell by 57% to $7.10 over the next three days.[41]
The Bitcoin Foundation was founded in September 2012 to promote bitcoin's
development and uptake.[42]
2013–2016
In 2013, prices started at $13.30 rising to $770 by 1 January 2014.[38]
In March 2013 the blockchain temporarily split into two independent chains
with different rules due to a bug in version 0.8 of the bitcoin software.
The two blockchains operated simultaneously for six hours, each with
its own version of the transaction history from the moment of the split.
Normal operation was restored when the majority of the network downgraded
to version 0.7 of the bitcoin software, selecting the backward compatible
version of the blockchain. As a result, this blockchain became the longest
chain and could be accepted by all participants, regardless of their bitcoin
software version.[43] During the split, the Mt. Gox exchange briefly halted
bitcoin deposits and the price dropped by 23% to $37[43][44] before
recovering to previous level of approximately $48 in the following hours.[45]
 The US Financial Crimes Enforcement Network (FinCEN) established regulatory
guidelines for "decentralized virtual currencies" such as bitcoin,
classifying American bitcoin miners who sell their generated bitcoins as Money
Service Businesses (MSBs), that are subject to registration or other legal obligations
.[46][47][48] In April, exchanges BitInstant and Mt. Gox experienced processing
delays due to insufficient capacity[49] resulting in the bitcoin price dropping
from $266 to $76 before returning to $160 within six hours.[50] The bitcoin
price rose to $259 on 10 April, but then crashed by 83% to $45 over the next
three days.[41] On 15 May 2013, US authorities seized accounts associated
with Mt. Gox after discovering it had not registered as a money transmitter
with FinCEN in the US.[51][52] On 23 June 2013, the US Drug Enforcement Administration
listed ₿11.02 as a seized asset in a United States Department of Justice
seizure notice pursuant to 21 U.S.C. § 881.[53][better source needed]
This marked the first time a government agency had seized bitcoin.[54]
The FBI seized about ₿30,000[55] in October 2013 from the dark web
website Silk Road during the arrest of Ross William Ulbricht.[56][57][58]
These bitcoins were sold at blind auction by the United States Marshals Service
to venture capital investor Tim Draper.[55] Bitcoin's price rose to $755 on 19
November and crashed by 50% to $378 the same day. On 30 November 2013
the price reached $1,163 before starting a long-term crash, declining
by 87% to $152 in January 2015.[41] On 5 December 2013,
the People's Bank of China prohibited Chinese financial institutions
from using bitcoins.[59] After the announcement, the value of bitcoins dropped
,[60] and Baidu no longer accepted bitcoins for certain services.
[61] Buying real-world goods with any virtual currency had been
illegal in China since at least 2009.[62]
In 2014, prices started at $770 and fell to $314 for the year.[38]
On July 30, 2014, the Wikimedia Foundation started accepting donations of bitcoin.[63]
In 2015. prices started at $314 and rose to $434 for the year.
In 2016 prices rose to $998 on 1 January 2017.[38]
2017–2018
Prices started at $998 in 2017 and rose to $13,412.44 on 1 January 2018,[38]
after reaching its all time high of $19,783.06 on 17 December 2017.[64]
China banned trading in bitcoin, with first steps taken in September 2017,
and a complete ban that started on 1 February 2018. Bitcoin prices then
fell from $9,052 to $6,914 on 5 February 2018.[41] The percentage
of bitcoin trading in the Chinese renminbi fell from over 90% in September
2017 to less than 1% in June 2018.[65]
Throughout the rest of the first half of 2018, bitcoin's price fluctuated between
$11,480 and $5,848. On 1 July 2018, bitcoin's price was $6,343.[66][67]
The price on January 1, 2019 was $3,747, down 72% for 2018 and down 81% since
the all-time high.[66][68]
Bitcoin prices were negatively affected by several hacks or thefts from
cryptocurrency exchanges, including thefts from Coincheck in January 2018,
Coinrail and Bithumb in June, and Bancor in July. For the first six months of 2018, $761 million
worth of cryptocurrencies was reported stolen from exchanges.[69]
Bitcoin's price was affected even though other cryptocurrencies were stolen at Coinrail and Bancor
as investors worried about the security of cryptocurrency exchanges.[70][71][72]
Design
Units
The unit of account of the bitcoin system is a bitcoin. Ticker symbols used to represent
bitcoin are BTC and XBT.[c][77]:2 Its Unicode character is ₿.[1] Small amounts
of bitcoin used as alternative units are millibitcoin (mBTC),
and satoshi (sat). Named in homage to bitcoin's creator,
a satoshi is the smallest amount within bitcoin representing
0.00000001 bitcoins, one hundred millionth of a bitcoin.[2]
A millibitcoin equals 0.001 bitcoins; one thousandth of a bitcoin
or 100,000 satoshis.[78]
Blockchain
[Image: 220px-Bitcoin_Block_Data.png]
Data structure of blocks in the ledger.
[Image: 200px-BTC_number_of_transactions_per_month.png]
Number of bitcoin transactions per month (logarithmic scale)[79]
[Image: 200px-Utxo-count.svg.png]
Number of unspent transaction outputs
For broader coverage of this topic, see Blockchain.
The bitcoin blockchain is a public ledger that records bitcoin

transactions.[80] It is implemented as a chain of blocks, each
block containing a hash of the previous block up to the genesis
block[d] of the chain. A network of communicating nodes running
bitcoin software maintains the blockchain.[37]:215–219 Transactions
of the form payer X sends Y bitcoins to payee Z are broadcast to this
network using readily available software applications.
Network nodes can validate transactions, add them to their copy of

the ledger, and then broadcast these ledger additions to other nodes.
To achieve independent verification of the chain of ownership each network
node stores its own copy of the blockchain.[81] About every 10 minutes,
a new group of accepted transactions, called a block, is created,
added to the blockchain, and quickly published to all nodes,
without requiring central oversight. This allows bitcoin software to
determine when a particular bitcoin was spent, which is needed to
prevent double-spending. A conventional ledger records the transfers
of actual bills or promissory notes that exist apart from it,
but the blockchain is the only place that bitcoins can be said to
exist in the form of unspent outputs of transactions.[7]:ch. 5
Transactions
See also: Bitcoin network
Transactions are defined using a Forth-like scripting language.[7]:ch. 5

Transactions consist of one or more inputs and one or more
outputs. When a user sends bitcoins, the user designates each
address and the amount of bitcoin being sent to that address
in an output. To prevent double spending, each input must refer
to a previous unspent output in the blockchain.[82] The use of
multiple inputs corresponds to the use of multiple coins in a cash
transaction. Since transactions can have multiple outputs, users
can send bitcoins to multiple recipients in one transaction. As in a
cash transaction, the sum of inputs (coins used to pay)
can exceed the intended sum of payments. In such a case,
an additional output is used, returning the change back to the
payer.[82] Any input satoshis not accounted for in the transaction
outputs become the transaction fee.[82]
Transaction fees
Though transaction fees are optional, miners can choose which

transactions to process and prioritize those that pay higher fees.[82]
Miners may choose transactions based on the fee paid relative
to their storage size, not the absolute amount of money paid as a fee.
These fees are generally measured in satoshis per byte (sat/b).
The size of transactions is dependent on the number of inputs used to
create the transaction, and the number of outputs.[7]:ch. 8
Ownership
[Image: 220px-Bitcoin_Transaction_Visual.svg.png]
Simplified chain of ownership as illustrated in the bitcoin whitepaper.[4]

In practice, a transaction can have more than one input
and more than one output.[82]
In the blockchain, bitcoins are registered to bitcoin addresses.

Creating a bitcoin address requires nothing more than picking
a random valid private key and computing the corresponding bitcoin address.
This computation can be done in a split second. But the reverse,
computing the private key of a given bitcoin address,
is mathematically unfeasible. Users can tell others or make
public a bitcoin address without compromising its corresponding
private key. Moreover, the number of valid private keys is so vast
that it is extremely unlikely someone will compute a key-pair that
is already in use and has funds. The vast number of valid private
keys makes it unfeasible that brute force could be used to compromise
a private key. To be able to spend their bitcoins, the owner
must know the corresponding private key and digitally sign
the transaction. The network verifies the signature using
the public key; the private key is never revealed.[7]:ch. 5
If the private key is lost, the bitcoin network will not recognize any

other evidence of ownership;[37] the coins are then unusable,
and effectively lost. For example, in 2013 one user claimed to
have lost 7,500 bitcoins, worth $7.5 million at the time, when
he accidentally discarded a hard drive containing
his private key.[83] About 20% of all bitcoins are believed to
be lost. They would have a market value of about $20 billion at July 2018 prices.[84]
To ensure the security of bitcoins, the private key must be

kept secret.[7]:ch. 10 If the private key is revealed to
a third party, e.g. through a data breach, the third party can
use it to steal any associated bitcoins.[85] As of December 2017,
around 980,000 bitcoins have been stolen from cryptocurrency exchanges.[86]
Regarding ownership distribution, as of 16 March 2018, 0.5%

of bitcoin wallets own 87% of all bitcoins ever mined.[87]
Mining
[Image: 137px-Minage_de_crypto-monnaie_%282%29.jpg]
Early bitcoin miners used GPUs for mining, as they were better

suited to the proof-of-work algorithm than CPUs.[88]
[Image: 139px-USB_Erupter.jpg]
Later amateurs mined bitcoins with specialized FPGA and ASIC

chips. The chips pictured have become obsolete due to increasing difficulty.
[Image: 183px-Cryptocurrency_Mining_Farm.jpg]
Today, bitcoin mining companies dedicate facilities to housing

and operating large amounts of high-performance mining hardware.[89]
[Image: 220px-History_of_Bitcoin_difficulty.svg.png]
Semi-log plot of relative mining difficulty[e][79]
Mining is a record-keeping service done through the use of

computer processing power.[f] Miners keep the blockchain
consistent, complete, and unalterable by repeatedly grouping
newly broadcast transactions into a block, which is then broadcast
to the network and verified by recipient nodes.[80] Each
block contains a SHA-256 cryptographic hash of the previous
block,[80] thus linking it to the previous block and giving the
blockchain its name.[7]:ch. 7[80]
To be accepted by the rest of the network, a new block must

contain a proof-of-work (PoW).[80] The system used is based
on Adam Back's 1997 anti-spam scheme, Hashcash.[91][failed verification][4]
The PoW requires miners to find a number called a nonce,
such that when the block content is hashed along with the
nonce, the result is numerically smaller than the network's
difficulty target.[7]:ch. 8 This proof is easy for any node in the
network to verify, but extremely time-consuming to generate,
as for a secure cryptographic hash, miners must try many
different nonce values (usually the sequence of tested values is
the ascending natural numbers: 0, 1, 2, 3, ...[7]:ch. 8) before
meeting the difficulty target.
Every 2,016 blocks (approximately 14 days at roughly 10 min per block),

the difficulty target is adjusted based on the network's recent performance,
with the aim of keeping the average time between
new blocks at ten minutes. In this way the system
automatically adapts to the total amount of mining power on
the network.[7]:ch. 8 Between 1 March 2014 and 1 March 2015,
the average number of nonces miners had to try before creating
a new block increased from 16.4 quintillion to 200.5 quintillion.[92]
The proof-of-work system, alongside the chaining of blocks, makes

modifications of the blockchain extremely hard, as an attacker must
modify all subsequent blocks in order for the modifications of one
block to be accepted.[93] As new blocks are mined all the time,
the difficulty of modifying a block increases as time passes and
the number of subsequent blocks (also called confirmations of the given block) increases.[80]
Supply
[Image: 220px-Total-bitcoins.svg.png]
Total bitcoins in circulation.[79]
The successful miner finding the new block is allowed by the

rest of the network to reward themselves with newly created
bitcoins and transaction fees.[94] As of 9 July 2016,[95] the
reward amounted to 12.5 newly created bitcoins per block added
to the blockchain, plus any transaction fees from payments
processed by the block. To claim the reward, a special transaction called
a coinbase is included with the processed payments.[7]:ch. 8 All bitcoins in
existence have been created in such coinbase transactions.
The bitcoin protocol specifies that the reward for adding a block will be
halved every 210,000 blocks (approximately every four years).
Eventually, the reward will decrease to zero, and the limit of 21 million bitcoins[g]
will be reached c. 2140; the record keeping will then be
rewarded solely by transaction fees.[96]
In other words, Nakamoto set a monetary policy based on artificial scarcity at bitcoin's inception that the total number of bitcoins could never exceed 21 million.

New bitcoins are created roughly every ten minutes and the
rate at which they are generated drops by half about every four years until all will be in circulation.[97]
Pooled mining
For broader coverage of this topic, see Mining pool.
Computing power is often bundled together or "pooled" to

reduce variance in miner income. Individual mining rigs often
have to wait for long periods to confirm a block of transactions and
receive payment. In a pool, all participating
miners get paid every time a participating server solves a block.
This payment depends on the amount of work an individual miner contributed to help find that block.[98]
Wallets
For broader coverage of this topic, see Cryptocurrency wallet.
[Image: 191px-Screenshot_of_Bitcoin-qt-0.5.2.png]
Bitcoin Core, a full client
[Image: 209px-Electrum_Bitcoin_Wallet.png]
Electrum, a lightweight client
A wallet stores the information necessary to transact bitcoins. While wallets are often described as a place to hold[99] or store bitcoins, due to the nature of the system, bitcoins are inseparable from the blockchain transaction ledger. A wallet is more correctly defined as something that "stores the digital credentials for your bitcoin holdings" and allows one to access (and spend) them.[7]:ch. 1, glossary Bitcoin uses public-key cryptography, in which two cryptographic keys, one public and one private, are generated.[100] At its most basic, a wallet is a collection of these keys.
There are several modes which wallets can operate in. They have an inverse relationship with regards to trustlessness and computational requirements.
  • Full clients verify transactions directly by downloading a full copy of the blockchain (over 150 GB As of January 2018).[101] They are the most secure and reliable way of using the network, as trust in external parties is not required. Full clients check the validity of mined blocks, preventing them from transacting on a chain that breaks or alters network rules.[7]:ch. 1 Because of its size and complexity, downloading and verifying the entire blockchain is not suitable for all computing devices.
  • Lightweight clients consult full clients to send and receive transactions without requiring a local copy of the entire blockchain (see simplified payment verificationSPV). This makes lightweight clients much faster to set up and allows them to be used on low-power, low-bandwidth devices such as smartphones. When using a lightweight wallet, however, the user must trust the server to a certain degree, as it can report faulty values back to the user. Lightweight clients follow the longest blockchain and do not ensure it is valid, requiring trust in miners.[102]

Third-party internet services called online wallets offer similar functionality but may be easier to use. In this case, credentials to access funds are stored with the online wallet provider rather than on the user's hardware.[103] As a result, the user must have complete trust in the online wallet provider. A malicious provider or a breach in server security may cause entrusted bitcoins to be stolen. An example of such a security breach occurred with Mt. Gox in 2011.[104]
Physical wallets
[Image: 195px-Bitcoin_paper_wallet_generated_at_bitaddress.jpg]
A paper wallet with a banknote-like design. Both the private key and the address are visible in text form and as 2D barcodes.
[Image: 205px-Sample_Bitcoin_paper_wallet.png]
A paper wallet with the address visible for adding or checking stored funds. The part of the page containing the private key is folded over and sealed.
[Image: 171px-Casascius_coin.jpg]
A brass token with a private key hidden beneath a tamper-evident security hologram. A part of the address is visible through a transparent part of the hologram.
[Image: 229px-10elqpi.jpg]
A hardware wallet peripheral which processes bitcoin payments without exposing any credentials to the computer.
Physical wallets store the credentials necessary to spend bitcoins offline and can be as simple as a paper printout of the private key:[7]:ch. 10 a paper wallet. A paper wallet is created with a keypair generated on a computer with no internet connection; the private key is written or printed onto the paper[h] and then erased from the computer. The paper wallet can then be stored in a safe physical location for later retrieval. Bitcoins stored using a paper wallet are said to be in cold storage.[105]:39 In a 2014 interview, QuadrigaCX founder Gerald Cotten explained that the company stored customer funds on paper wallets in safe deposit boxes: "So we just send money to them, we don’t need to go back to the bank every time we want to put money into it. We just send money from our Bitcoin app directly to those paper wallets, and keep it safe that way."[106]
Cameron and Tyler Winklevoss, the founders of the Gemini Trust Co. exchange, reported that they had cut their paper wallets into pieces and stored them in envelopes distributed to safe deposit boxes across the United States.[107] Through this system, the theft of one envelope would neither allow the thief to steal any bitcoins nor deprive the rightful owners of their access to them.[106]
Physical wallets can also take the form of metal token coins[108] with a private key accessible under a security hologram in a recess struck on the reverse side.[109]:38 The security hologram self-destructs when removed from the token, showing that the private key has been accessed.[110] Originally, these tokens were struck in brass and other base metals, but later used precious metals as bitcoin grew in value and popularity.[109]:80 Coins with stored face value as high as ₿1000 have been struck in gold.[109]:102–104 The British Museum's coin collection includes four specimens from the earliest series[109]:83 of funded bitcoin tokens; one is currently on display in the museum's money gallery.[111] In 2013, a Utahn manufacturer of these tokens was ordered by the Financial Crimes Enforcement Network (FinCEN) to register as a money services business before producing any more funded bitcoin tokens.[108][109]:80
Another type of physical wallet called a hardware wallet keeps credentials offline while facilitating transactions.[112] The hardware wallet acts as a computer peripheral and signs transactions as requested by the user, who must press a button on the wallet to confirm that they intended to make the transaction. Hardware wallets never expose their private keys, keeping bitcoins in cold storage even when used with computers that may be compromised by malware.[105]:42–45
Implementations
Further information: Bitcoin Core
The first wallet program, simply named Bitcoin, and sometimes referred to as the Satoshi client, was released in 2009 by Satoshi Nakamoto as open-source software.[16] In version 0.5 the client moved from the wxWidgets user interface toolkit to Qt, and the whole bundle was referred to as Bitcoin-Qt.[113] After the release of version 0.9, the software bundle was renamed Bitcoin Core to distinguish itself from the underlying network.[114][115]
Forks
See also: Fork (blockchain) and List of bitcoin forks
Bitcoin Core is, perhaps, the best known implementation or client. Alternative clients (forks of Bitcoin Core) exist, such as Bitcoin XT, Bitcoin Unlimited,[36] and Parity Bitcoin.[116]
On 1 August 2017, a hard fork of bitcoin was created, known as Bitcoin Cash.[117] Bitcoin Cash has a larger block size limit and had an identical blockchain at the time of fork. On 24 October 2017 another hard fork, Bitcoin Gold, was created. Bitcoin Gold changes the proof-of-work algorithm used in mining, as the developers felt that mining had become too specialized.[118]
Decentralization
Bitcoin does not have a central authority and the bitcoin network is decentralized:[8]
  • There is no central server; the bitcoin network is peer-to-peer.[16]
  • There is no central storage; the bitcoin ledger is distributed.[119]
  • The ledger is public; anybody can store it on their computer.[7]:ch. 1
  • There is no single administrator;[8] the ledger is maintained by a network of equally privileged miners.[7]:ch. 1
  • Anybody can become a miner.[7]:ch. 1
  • The additions to the ledger are maintained through competition. Until a new block is added to the ledger, it is not known which miner will create the block.[7]:ch. 1
  • The issuance of bitcoins is decentralized. They are issued as a reward for the creation of a new block.[94]
  • Anybody can create a new bitcoin address (a bitcoin counterpart of a bank account) without needing any approval.[7]:ch. 1
  • Anybody can send a transaction to the network without needing any approval; the network merely confirms that the transaction is legitimate.[120]:32

Trend towards centralization
Researchers have pointed out at a "trend towards centralization". Although bitcoin can be sent directly from user to user, in practice intermediaries are widely used.[37]:220–222 Bitcoin miners join large mining pools to minimize the variance of their income.[37]:215, 219–222[121]:3[122] Because transactions on the network are confirmed by miners, decentralization of the network requires that no single miner or mining pool obtains 51% of the hashing power, which would allow them to double-spend coins, prevent certain transactions from being verified and prevent other miners from earning income.[123] As of 2013 just six mining pools controlled 75% of overall bitcoin hashing power.[123] In 2014 mining pool Ghash.io obtained 51% hashing power which raised significant controversies about the safety of the network. The pool has voluntarily capped their hashing power at 39.99% and requested other pools to act responsibly for the benefit of the whole network.[124] c. 2017 over 70% of the hashing power and 90% of transactions were operating from China.[125]
According to researchers, other parts of the ecosystem are also "controlled by a small set of entities", notably the maintenance of the client software, online wallets and simplified payment verification (SPV) clients.[123]
Privacy
Bitcoin is pseudonymous, meaning that funds are not tied to real-world entities but rather bitcoin addresses. Owners of bitcoin addresses are not explicitly identified, but all transactions on the blockchain are public. In addition, transactions can be linked to individuals and companies through "idioms of use" (e.g., transactions that spend coins from multiple inputs indicate that the inputs may have a common owner) and corroborating public transaction data with known information on owners of certain addresses.[126] Additionally, bitcoin exchanges, where bitcoins are traded for traditional currencies, may be required by law to collect personal information.[127] To heighten financial privacy, a new bitcoin address can be generated for each transaction.[128]
Fungibility
Wallets and similar software technically handle all bitcoins as equivalent, establishing the basic level of fungibility. Researchers have pointed out that the history of each bitcoin is registered and publicly available in the blockchain ledger, and that some users may refuse to accept bitcoins coming from controversial transactions, which would harm bitcoin's fungibility.[129] For example, in 2012, Mt. Gox froze accounts of users who deposited bitcoins that were known to have just been stolen.[130]
 

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