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CHAPTER 1

Introduction to Bitcoin

Lam Pak Nian, David LEE Kuo Chuen

Sim Kee Boon Institute for Financial Economics, Singapore Management University, Singapore

Contents

1.1 The Next Generation of Money and Payments 6

1.2 Digital Currency as Alternative Currency 6

1.2.1 "Digital " versus "virtual " 6

1.2.2 Classifying alternative currencies 6

1.2.3 Why alternative currencies 7

1.3 Cryptocurrency 8

1.3.1 The nature of cryptocurrency 8

1.3.2 The beginning: eCash 8

1.3.3 Pioneering Internet payments with digital gold 9

1.3.4 Revival of cryptocurrency 9

1.3.5 The rise of Bitcoin 11

1.4 General Features of Bitcoin 14

1.4.1 Network and digital currency 14

1.4.2 Genesis and decentralized control 15

1.4.3 How Bitcoin works 15

1.4.4 Buying and storing bitcoins 17

1.4.5 Mining to create new bitcoins and process transactions 19

1.4.6 Security and cryptography 20

1.4.7 Pseudoanonymity 21

1.5 Benefits and Risks 22

1.5.1 Freedom of payments 22

1.5.2 Merchant benefits 23

1.5.3 User control 23

1.5.4 Platform for further innovation 24

1.5.5 Internal change and volatility 24

1.5.6 Facilitation of criminal activity 24

1.5.7 Legal regulatory attitude 25

1.5.8 Economic risk 25

1.6 Impact of the Digital Currency Revolution 25

1.7 Conditions for a Successful Cryptocurrency 26

1.7.1 Ecosystem 26

1.7.2 Incentives 26

1.7.3 Identification 27

1.8 Future Prospects and Conclusion 27

Acknowledgments 29

References 29

1.1 THE NEXT GENERATION OF MONEY AND PAYMENTS

There are various innovative money payment systems in the market today, many of

which are built on platforms like the mobile phone, the Internet, and the digital storage

card. These alternative payment systems have seen encouraging or even continued

growth, from the likes of PayPal, Apple Pay, Google Wallet, Alipay, Tenpay, Venmo,

M-Pesa, BitPay, Moven, BitPesa, PayLah!, Dash, FAST, Transferwise, and others.

Beyond payment systems that are based on fiat currency, the growing use of digital

currency allows for faster, more flexible, and more innovative payments and ways in

financing goods and services. One digital currency, however, stands out among the rest.

Bitcoin is one of the most well-known digital currencies today. To be specific, Bitcoin is

acrypto currency, which is a subset of what is generally known as a digital currency. Bitcoin

is a unique cryptocurrency that is widely considered to be the first of its kind. Like many

created after it, Bitcoin uses the power of the Internet to process its transactions. This

chapter introduces the characteristics and features of Bitcoin and sets the stage for further

discussion of cryptocurrencies in the rest of this book.

1.2 DIGITAL CURRENCY AS ALTERNATIVE CURRENCY

1.2.1 " Digital" versus " virtual"

Although digital and virtual are often used interchangeably when describing currencies

based on an electronic medium, the term "virtual" has a negative connotation. "Virtual"

signals something that is "seemingly real" but not exactly "real" when referring to a cur-

rency that is stored in a "digital" or electronic register. Indeed, in languages like Chinese,

the word "virtual" is interpreted as "created from nothing" (虚拟的 ) in the sense that it is

not "physical" but computer-generated or computer-simulated. However, the curren-

cies often described as "virtual" are very "real," in the sense that they exist. Thus, the

more neutral term digital currency is generally preferred over virtual currency.

1.2.2 Classifying alternative currencies

Alternative currencies refer to a medium of exchange other than fiat currency. Historically,

there are various types of alternativecurrencies, asclassified by Hileman (2014) broadly into

two categories: tangible and digital. Tangible currencies, closelyassociated with "commod-

ity money," derive their value from relative scarcity and nonmonetary utility:

(a) Currencies with intrinsic utility

This class of currency includes metals and cigarettes in post-WWII Berlin and

more contemporary examples are prepaid phone cards and, to some extent, cash

value smart cards. This class is not dependent upon governance as in the case of

6Handbook of Digital Currency

monetary instruments, and more importantly, its intrinsic value is not an abstraction

and it is not necessarily geographically bound.

(b) Token

Seventeenth- to nineteenth-century British tokens and the Great Depression

scrip of the 1930s are historical examples. More contemporary examples are local

or community currencies such as Brixton Pound and Bristol Pound that are used

in England, BerkShares that is circulated in Berkshire region of Massachusetts,

and Salt Spring Dollar in Canada. Token has less intrinsic value as its use is more

specific and usually bounded by some social contracts or agreement such as honoring

them for exchange for goods or to limit the supply of goods.

Examples are loyalty points from financial, telecom, or retail companies; air miles

from airlines; Second Life's Linden Dollar and World of Warcraft Gold, which are

closed system with transactions within specific entities; and Flooz and Beenz, which

are open market system and can be transacted with other entities. Local currencies

such as Brixton Pound, BerkShares, and Salt Spring Dollar also fall under this cate-

gory besides being classified as tokens. The governance structure is centralized.

(d) Distributed and/or decentralized digital currency

This includes the cryptocurrencies such as Bitcoin, Litecoin, and Dogecoin.

They can be transacted with any outside agents and the governance is decentralized

mainly but not necessary due to open-source software. There is no legal entity

responsible for the activities, and therefore, they fall outside traditional regulation.

1.2.3 Why alternative currencies

There are various socioeconomic forces that drive the demand for alternative currencies:

(a) Localism

By promoting community commerce or "save high street," localism retains con-

sumption within a group of independent retailers or within a geographic area for job

creation and improved business conditions.

(b) Technology

It has become much easier to use with improved software and low entry barriers

contributing to network effects.

There is disillusionment about the high pay of CEOs and bankers and the notion

of traditional banks being too big to fail. With high debt and quantitative easing,

there is great discomfort with the economic uncertainty.

(d) Environmentalism

There are ecology concerns and the question of whether we have reached the

point of maximum extraction of natural resources such as oil.

7 Introduction to Bitcoin

(e) Inefficiencies

Financial services are overpriced and whole financial system is too expensive.

(f) Financial freedom

Some digital currencies such as cryptocurrencies have the advantage of transfer-

ring value through the Internet where control is weak. Such digital currencies may

allow users to bypass capital controls and may provide safe harbor during a fiat cur-

rency crisis.

(g) Speculation

Buyers of some digital currencies such as cryptocurrencies are anticipating a price

appreciation due to subsequent wider acceptance.

It is very easy to create a cryptocurrency as an alternative currency for free today. How-

ever, most of these new creations will cease circulation within a relatively short time.

With many alternative currencies in competition, only a few will be globally adopted,

reach a sufficient scale, or find a suitable market. Unless the idea of national digital

currencies takes off, it is likely that many of these alternative currencies will cease

circulation because of superseding advancements in technology, tighter regulation,

and insufficient demand.

1.3 CRYPTOCURRENCY

1.3.1 The nature of cryptocurrency

Cryptocurrency in its purest form is a peer-to-peer version of electronic cash. It allows

online payments to be sent directly from one party to another without going through a

financial institution. The network time-stamps transactions using cryptographic proof of

work. The proof-of-work Bitcoin protocol is basically a contest for decoding and an

incentive to reward those who participate. For Bitcoin, first participant to crack the code

will be rewarded with the newly created coins. This contest will form a record of the

transactions that cannot be changed without redoing the proof of work.

Cryptocurrency is a subset of digital currency. Examples of the many digital curren-

cies are air miles issued by airlines, game tokens for computer games and online casinos,

Brixton Pound to be spent only in the Brixton local community in the Greater London

area, and many other forms that can be exchanged for virtual and physical objects in a

closed system and, in the case of an open system, exchanged for fiat currency.

1.3.2 The beginning: eCash

Commercially, it all began with DigiCash, Inc.'s eCash system in 1990, based on two

papers by its founder (Chaum, 1983 ; Chaum et al., 1992 ). Payments were transferred

online and offline using cryptographic protocols to prevent double-spending. The

cryptographic protocols also used blind signatures to protect the privacy of its users.

8Handbook of Digital Currency

As the first cryptocurrency, the eCash system was available via various banks and smart

cards in various countries like the United States and Finland. It slowly evolved into the

current form of cryptocurrencies with many refinements by various software developers

over the last 20 years.

eCash was a centralized system owned by DigiCash, Inc. and later eCash Technol-

ogies. However, after it was acquired by InfoSpace in 1999, eCash and cryptocurrency

faded into the background.

1.3.3 Pioneering Internet payments with digital gold

Digital gold currency came into the limelight between 1999 and the early 2000s. Most of

these new forms of electronic money based on ounces of gold are stored at the bullion and

storage fees are charged. We have seen the growth of e-dinar, Pecunix, iGolder, Liberty

Reserve, gBullion, e-gold, and eCache. With a couple of exceptions, most have ended

up in the graveyard due to either compliance issues or regulatory breaches.

e-Gold was a pioneer for Internet payments. As the first successful online micropay-

ment system, it pioneered many new techniques and methods for e-commerce, which

later became widely used in other online aspects. These techniques and methods include

making payments over a Secure Sockets Layer-encrypted connection and offering

an application programming interface to enable other websites to build services using

e-gold's transaction system. However, its Achilles heel was its failure to fulfill know-

your-customer (KYC) and suspicious transaction reporting requirements. With the

introduction of the US Patriot Act, compliance has been a major issue for money trans-

mitters. Furthermore, it has to contend with hackers and Internet fraud. Before the

motion to seize and liquidate the entire gold reserve of e-gold under asset forfeiture

law in 2008, e-gold was processing more than USD2 billion worth of precious metal

transactions per year. There are clear lessons to be learned by the cryptocurrency

community.

1.3.4 Revival of cryptocurrency

At the onset of the global financial crisis in 2008, interest on cryptocurrency was revived.

Cryptocurrency had the potential to counter a few problems associated with the fiat cur-

rency system, argued Szabo (2008) in a blog post just at the beginning of the global finan-

cial crisis. Given that it is cumbersome to transact using commodities, the concept of bit

gold was mooted. As the name suggests, there is gold to be mined and bit recorded on a

digital register. The digital record would resolve the issues of a trusted third party, and in

his own words,

Thus, it would be very nice if there were a protocol whereby unforgeably costly bits could be

created online with minimal dependence on trusted third parties, and then securely stored,

transferred, and assayed with similar minimal trust. Bit gold.

9 Introduction to Bitcoin

My proposal for bit gold is based on computing a string of bits from a string of challenge

bits, using functions called variously " client puzzle function,"" proof of work function,"or

"secure benchmark function. "The resulting string of bits is the proof of work. Where a

one-way function is prohibitively difficult to compute backwards, a secure benchmark func-

tion ideally comes with a specific cost, measured in compute cycles, to compute backwards."

Despite sounding technical, what Szabo described was a simple protocol that requires

participants to spend resources to mine the digital gold or bit gold, be rewarded, and

in the process validate the public digital register. What differentiated his approach from

failed digital currencies of the past were the timing of the financial crisis and the distrib-

uted nature of the protocol. The reward to the miners was one innovation and the free

access to digital record for the users was another. One of the reasons is that the nature of

the Internet makes collecting mandatory fees much harder, while voluntary subsidy is

much easier. Therefore, there must be no barrier to access content or digital record,

and there must be ease of use and voluntary payments.

Ideas were discussed in the literature, and technology was developed over time by a

group of cryptographers, old and new, such as Chaum (1983) on DigiCash, Back (1997)

on Hashcash, Dai (1998) on b-money, Szabo (1999, 2002, 2008) on the concept of

money, and Shirky (2000) on micropayments. Cypherpunk is an activist group since

the early 1980s that advocates the widespread use of strong cryptography as a route to

social and political changes. Finney (2004) , who ran two anonymous remailers as a

cypherpunk member, created the first reusable proof of work (RPOW), which is an eco-

nomic measure to deter denial-of-service attacks and other service abuses such as spam on

a network by requiring some work from the service requester. It means that whoever

requests for the information has to incur more processing time on a computer than

the provider. Hashcash, used by Bitcoin, is a proof-of-work system designed to limit

e-mail spam and denial-of-service attacks (Back, 2002).

At the same time, sociopolitical interest in cryptocurrency grew. Since we abandoned

the gold standard in 1971 and adopted the fiat currency system, central banks have used

their discretion to print as much as they desired during a crisis. This has created an asset

inflation environment and worsened income equality. The supply of cryptocurrency or

coins may or may not be limited but the new coins are usually created by a predetermined

rule. The loss of trust in the fiat currency system, caused mainly by quantitative easing and

huge government debts, has brought attention to cryptocurrency for those who wanted

to hedge their positions with a currency that has a finite supply.

Cryptocurrency was thought to possess the characteristics of a currency that can

impose fiscal discipline on the government and it is perceived to be a debt-free cur-

rency with a constant growth rate with finite supply. For asset managers who were

constantly seeking for negative correlation with their core portfolio, cryptocurrency

provided a glimpse of hope for a high-risk and complex asset class that enhances

the returns of a portfolio with bitcoins acting as a negatively correlated alternative asset

10 Handbook of Digital Currency

class. But the origins of Bitcoin have their roots in cryptoanarchy that started as a

movement in 1992:

Just as the technology of printing altered and reduced the power of medieval guilds and the

social power structure, so too will cryptologic methods fundamentally alter the nature of cor-

porations and of government interference in economic transactions. Combined with emerg-

ing information markets, crypto anarchy will create a liquid market for any and all material

which can be put into words and pictures. And just as a seemingly minor invention like barbed

wire made possible the fencing-off of vast ranches and farms, thus altering forever the con-

cepts of land and property rights in the frontier West, so too will the seemingly minor discov-

ery out of an arcane branch of mathematics come to be the wire clippers which dismantle the

barbed wire around intellectual property. (May1992)

The use of cryptocurrency as a safe haven and an alternative asset class was demonstrated

in the 2013 Cypriot property-related banking crisis where a 6.75% levy was imposed on

bank deposits up to EUR100k and 9.9% for larger deposits. With confidence in tradi-

tional banking shaken, investors were betting heavily on the most well-known crypto-

currency, bitcoins, to offer a more stable alternative. Many investors converted their fiat

money into cryptocurrency, sending the price and volume to spike. The price of bitcoins

spiked 57% within a week to USD74. Like gold and other commodities, Bitcoin's price

spikes in moments of uncertainty. Both assets are increasingly favored by a small group of

managers in alternative investment and critics of contemporary monetary policy. The

most common arguments against Bitcoin are (i) the lack of a central issuing authority like

that of a central bank, (ii) its fixed supply and deflationary nature by design, (iii) doubts

that the price is stable enough to function as a currency, and (iv) the risk associated with it.

1.3.5 The rise of Bitcoin

An example of a cryptocurrency is bitcoins. Satoshi Nakamoto published a paper on the

Web in 2008 for a peer-to-peer electronic cash system. Despite many efforts, the identity

of Satoshi remains unknown to the public and it is not known whether Satoshi is a group

or a person.

The cryptocurrency invented by Satoshi Nakamoto, called bitcoins, is run using

open-source software. It can be downloaded by anyone, and the system runs on a decen-

tralized peer-to-peer network. It is not only decentralized but also supposedly fully

Satoshi in Japanese means "wise" and someone has suggested that the name might be a portmanteau of four

technology companies: SAmsung, TOSHIba, NAKAmichi, and MOTOrola. Others have noted that it

could be a team from the National Security Agency (NSA) or an e-commerce firm (Wallace, 2011).

Other suggestions are David Chaum, the late Hal Finney, Nick Szabo, Wei Dai, Gavin Andresen, and

the Japanese living in the neighborhood of Finney by the same surname Dorian Nakamoto. There are

other suggestions such as Vili Lehdonvirta, Michael Clear, Neal King, Vladimir Oksman, Charles Bry,

Shinichi Mochizuki, Jed McCaleb, and Dustin Trammell, but most have publicly denied that they are

Satoshi.

Introduction to Bitcoin

distributed. That means that every node or computer terminal is connected to each other.

Every node can leave and rejoin the network at will and will later accept the longest proof

of work known as the blockchain as the authoritative record.

This longest blockchain is proof of what has happened while these nodes were gone.

Cryptocurrency is mysterious and misunderstood for a few reasons.

First, no one knows who is really behind some of these cryptocurrency systems. It was

designed so that third-party trust is not needed and sometimes there is no legal entity

behind it but open-source software.

Second, many have jokingly remarked that Bitcoin sounded more like "big con"

especially after the collapse of Mt. Gox. But it is important to note that Mt. Gox was

merely a financial intermediary, being just one of many unregulated exchanges that trade

in Bitcoins. Mt. Gox was not part the Bitcoin system itself. It is a complex currency sys-

tem to the men in the street and therein lies the confusion.

Third, cryptocurrency involves mining or proof of work. There are rewards for

mining and the reward is given to the first who can solve a cryptography problem.

The degree of difficulty of the problem will ensure that the timing to solve the prob-

lem is approximately 10 min for Bitcoin. Cryptocurrency cleverly solves the double-

spending problem so that every cryptocurrency can be spent only once. It is a financial

technology and it involves financial regulation but therein lies the difficulty in execu-

tion and understanding even for the professionals. That is why it is an area of great

interest to researchers, regulators, investors, and merchants and it is hitting the head-

lines regularly.

The general arguments for a successful distributed cryptocurrency are as follows:

1. Open-source software: A core and trusted group of developers is essential to verify the

code and possible changes for adoption by the network.

2. Decentralized: Even if it is not fully distributed, it is essential that it is not controlled by

a single group of person or entity.

3. Peer-to-peer: While the idea is not to have intermediaries, there is a possibility of pools

of subnetworks forming.

4. Global: The currency is global and this is a very positive point and workable for

financial integration with or without smart contracts among the parties.

5. Fast: The speed of transaction can be faster and confirmation time can be shortened.

6. Reliability: The advantage is that there is no settlement risk and it is nonrepudiable.

The savings in cost of a large settlement team for financial activities can be

potentially huge.

7. Secure: Privacy architecture can be better designed incorporating proof of identity with

encryption. If that is done, the issues surrounding Know Your Customer/Client

(KYC) and anti-money laundering and terrorist financing (AML/TF) will be resolved.

8. Sophisticated and flexible: The system will be able to cater to and support all types of

assets, financial instruments, and markets.

12 Handbook of Digital Currency

9. Automated: Algorithm execution for payments and contracts can be easily

incorporated.

10. Scalable: The system can be used by millions of users.

11. Platform for integration: It can be designed to integrate digital finance and digital law

with an ecosystem to support smart contracts with financial transactions. Custom-

ized agreements can be between multiple parties, containing user-defined scripted

clauses, hooks, and variables.

The possible applications will be wide-ranging and include global payment and remit-

tance systems, decentralized exchanges, merchant solutions, online gaming, and digital

contracting systems. Each cryptocurrency is a great and an interesting experiment. No

one knows where these cryptocurrency experiments are heading but the experiments

are interesting because of the technology that is developed along with them.

The technology disrupts the payment system as we know it because it costs almost

nothing to transfer payments. Cryptocurrency technology will allow us to reach out

to the unbanked and underbanked. It presents the opportunity to function as a conduit

for payments and funds. It will transform the way business is being done by diminishing

the role of the middleman, whether it is smart accounting or smart contract.

It will also change the way financial world operates especially in fund raising and lend-

ing. Basically, it is possible to do an Initial Crowd Offering or crowd lending, all in the

peer-to-peer framework, eliminating the middleman.

However, there are downsides or potential risks for cryptocurrency too. Cryptocur-

rency like Bitcoin depends on mining, and once the incentives for mining disappear, no

one knows if the cryptocurrency in question will continue to have consensus on the dig-

ital register. They are over 400 cryptocurrencies and the number is increasing on a daily

basis. But many of them are in the graveyard.

So, as they say, "let the buyer beware," because what you own may just be worthless

once there are doubts about the blockchain. It seems that if the cryptocurrency exhausts

most of their coin supply too fast and too early, the probability of the coins dying is

higher. For some coins, it is difficult to know who is behind them and whether there

could be a backdoor that allows someone to control the system. Cryptocurrency with

unknown developers has a higher probability of being buried in the graveyard.

The blockchain may come under attack as well. The blockchain serves as a proof of

the sequence of events as well as proof that it came from the largest pool of computing

power. As soon as the computing power is controlled by nodes that are cooperating to

attack the network, they may produce the longest chain of their choice creating doubts

about the validity of the blockchain. This can easily happen once the interest on a par-

ticular currency wanes and the number of miners shrinks, which opens up the possibility

of having a few blockchains in concurrent existence. Once there is any doubt of the accu-

racy of the blockchain, even if it was subsequently corrected, the coin will be heading for

the graveyard.

13 Introduction to Bitcoin

When there are no new coins to reward the miners, the system is unlikely to continue.

Once no new coins are issued as the mining reward, then the miners are expected to be

rewarded purely by transaction fees. This can be a problem. On the other hand, if the fees

are increased too quickly or to an unreasonable level, interest on the coins willwane as well.

With higher mining cost due to expensive equipment, mining pools will be formed. This is

because miners prefer higher probability of success in cracking the code. However, this will

lead to an undesirable outcome of mining pools exceeding 30% or even 50% of the net-

work, thus exposing the cryptocurrency to attack. This was indeed the case for Bitcoin

when the mining pool accounted for over 50% in the middle of 2014. This is one serious

problem that needs to be solved sooner rather than later and consensus ledger or digital

1.4 GENERAL FEATURES OF BITCOIN

1.4.1 Network and digital currency

Bitcoin is a decentralized network and a digital currency that uses a peer-to-peer system to

verify and process transactions. Instead of relying on trusted third parties, like banks and card

processors, to process payments, the Bitcoin technology uses cryptographic proof in its com-

puter software to process transactions and to verify the legitimacy of Bitcoins (Nakamoto,

2008) and spreads the processing work among thenetwork.Wemakeacleardistinction

between the Bitcoin system where a capital BisusedforthewordBitcoinandthatofa

Bitcoin, which is a unit of the currency or a digital address created by the Bitcoin system.

With the invention of Bitcoin, payments can be made over the Internet without the

control and costs of a central authority (Bitcoin Project ) for the first time. Prior to the

invention, transactions carried out online always required a third party as a trusted inter-

mediary to verify transactions (Brito and Castillo, 2013 ). For example, when Alice wants

to send $10 to Bob, she would have to use a third-party service like a credit card network

or PayPal. The function of the third-party service is to provide an assurance that the

sender, Alice, has the funds to transfer and that the recipient, Bob, has successfully

received the funds. This is possible because these intermediaries help maintain a record,

or ledger, of balances for their account holders. Here, when Alice sends Bob the $10, an

intermediary like PayPal would deduct the amount from her account and accordingly

add it to Bob's account, subject to a transaction fee.

However, the currency unit used in payments on the Bitcoin network is Bitcoins, not

a fiat currency. Therefore, bitcoins in itself is also a digital currency, in the sense that it

exists "digitally" and, for most intents and purposes, satisfies the economic definition of

money: it is a medium of exchange, unit of account, and store of value. Conventionally,

the uppercase "Bitcoin" refers to the network and technology, while the lowercase "bit-

coin(s)" refers to units of the currency. The currency is also commonly abbreviated to

"BTC," although some exchanges use "XBT," a proposed currency code that is com-

patible with ISO 4217 (Matonis, 2013).

14 Handbook of Digital Currency

1.4.2 Genesis and decentralized control

The first bitcoin was mined, or created, in 2009, following the online publication of a

paper by a Satoshi Nakamoto describing the proof of concept for a currency that uses

cryptography, rather than trust in a central authority (Nakamoto, 2008 ), to manage its

creation and transactions. Nakamoto left the project in 2010 and his identity largely

remains unknown. However, with the open-source nature of the Bitcoin software pro-

tocol, other developers have continued working on it and the Bitcoin community

flourishes today.

At the same time, although Nakamoto remains anonymous, users need not be con-

cerned that he, or anyone, secretly has full control of Bitcoin. The open-source nature of

Bitcoin means that the source code is fully disclosed. This disclosure allows any software

developer to examine the protocol and create their own versions of the software for test-

ing or further development, and so far, no red flag has been raised as to the presence of

Nakamoto or any other party with secret control. Furthermore, Bitcoin is designed to

operate only with full consensus of all network users. This ensures that software devel-

opers who modify the Bitcoin source code in their own versions of the software cannot

force a nefarious change in the Bitcoin protocol without breaking compatibility with the

rest of the network. The power to change the Bitcoin protocol requires full agreement

among Bitcoin users and developers.

1.4.3 How Bitcoin works

To a layperson, bitcoin is a digital currency that is created and held electronically. These

bitcoins are sent and received using a mobile app, computer software, or service provider

that provides a bitcoin wallet. The wallet generates an address, akin to a bank account

number, except that a Bitcoin address is a unique alphanumeric sequence of characters

where the user can start to receive payments. Usually, bitcoins may be obtained by

buying them at a Bitcoin exchange or vending machine or as payment for goods and

services.

However, Bitcoin is revolutionary because the double-spending problem can be

solved without needing a third party. In computer science, the double-spending problem

refers to the problem that digital money could be easily spent more than once. Consider

the situation where digital money is merely a computer file, just like a digital document.

Alice could send $10 to Bob by sending a money file to him and can easily do so by

e-mail. However, remember that sending a file actually sends a copy of the file and does

not delete the original file from the computer. When Alice attaches a money file in

an e-mail to Bob, she still retains a copy of the money file even after she has sent and

therefore spent it. Without a trusted third-party intermediary to ensure otherwise, Alice

could easily send the same $10 to another person, Charlie.

Bitcoin solves the double-spending problem by maintaining a ledger of balances,

but instead of relying on a single trusted third party to manage this ledger, Bitcoin

15 Introduction to Bitcoin

decentralizes this responsibility to the entire network. Behind the scenes, the Bitcoin

network constantly keeps track of bitcoin balances in a public ledger called the block-

chain. The blockchain is a publicly accessible authoritative record of all transactions

ever processed, allowing anyone to use Bitcoin software to verify the validity of a

transaction. Transfers of bitcoins, or transactions, are broadcast to the entire network

and are included onto the blockchain upon successful verification, so that spent bit-

coins cannot be spent again. New transactions are checked against the blockchain

to make sure that the bitcoins have not been already spent, thus solving the

double-spending problem.

Bitcoin extensively uses public-key cryptography to solve the double-spending prob-

lem. In public-key cryptography, each transaction has a digital signature and contains a

hash that allows for easy tamper detection (see Figures 1.1 and 1.2 for an example of a

Bitcoin transaction).

{

"hash":"e9a66845e05d5abc0ad04ec80f774a7e585c6e8db975962d069a522137b8

0c1d",

"ver":1,

"vin_sz":1,

"vout_sz":1,

"lock_time":0,

"size":225,

"in":[

{

"prev_out":{

"hash":"f4515fed3dc4a19b90a317b9840c243bac26114cf637522373a7d486b372

600b",

"n":0

"scriptSig":"3046022100bb1ad26df930a51cce110cf44f7a48c3c561fd977500b

1ae5d6b6fd13d0b3f4a022100c5b42951acedff14abba2736fd574bdb465f3e6f8da

12e2c5303954aca7f78f301

04a7135bfe824c97ecc01ec7d7e336185c81e2aa2c41ab175407c09484ce9694b449

53fcb751206564a9c24dd094d42fdbfdd5aad3e063ce6af4cfaaea4ea14fbb"

}

"out":[

{

"value":"0.01000000",

061HSAH_POPUD_PO":"yeKbuPtpircs"

39aa3d569e06a1d7926dc4be1193c99bf2eb9ee0 OP_EQUALVERIFY OP_CHECKSIG"

}

]

}

Figure 1.1 Example of a raw transaction data.

16 Handbook of Digital Currency

1.4.4 Buying and storing bitcoins

Against this technical backdrop, bitcoins are often used simply as payment in exchange

for goods and services (Kaplanov, 2012 ). While the numbers of brick-and-mortar mer-

chants who accept payments in bitcoins remain low, there are many more online

General information about this transaction

Hash e9a66845e05d5abc0ad04ec80f

774a7e585c6e8db975962d069a

522137b80c1d

The hash for this transaction

Block 100000 (2010-12-29

11:57:43)

Obtained from examining the block on

the blockchain where this transaction

was found

Version 1 Bitcoin software version

Size 225 The filesize in bytes of the transaction is

recorded in the transaction data itself

Input

from

output

f4515fed3dc4a19b90a317b984

0c243bac26114cf637522373a7

d486b372600b

The truncated hash of the previous

transaction which provides the bitcoins

to be sent for this transaction

amount

0.01 The amount in the previous transaction

which provides the bitcoins to be sent

for this transaction

Public

address

1JxDJCyWNakZ5kECKdCU9Zka6m

h34mZ7B2

The public address of the sender,

obtained from examining the blockchain

Signature 3046022100bb1ad26df930a51c

ce110cf44f7a48c3c561fd9775

00b1ae5d6b6fd13d0b3f4a0221

00c5b42951acedff14abba2736

fd574bdb465f3e6f8da12e2c53

03954aca7f78f301

04a7135bfe824c97ecc01ec7d7

e336185c81e2aa2c41ab175407

c09484ce9694b44953fcb75120

6564a9c24dd094d42fdbfdd5aa

d3e063ce6af4cfaaea4ea14fbb

The digital signature of the transaction,

signed by the sender

Output to

Index 0 "0" indicates the first recipient in the

transaction; here this transaction only

has one recipient

Amount 0.01 Amount sent to this user in this

transaction

Public

address

16FuTPaeRSPVxxCnwQmdyx2PQW

xX6HWzhQ

The public address of the recipient,

obtained from the scriptPubKey

Bitcoin

address

(scriptPubK

ey)

39aa3d569e06a1d7926dc4be11

93c99bf2eb9ee0

A hash160 of the public address

Conditions OP_DUP

OP_HASH160

OP_EQUALVERIFY

OP_CHECKSIG

Conditions to be met together with the

scriptPubKey for the output bitcoins to

be redeemed by the recipient

Figure 1.2 Explanation for the transaction.

Introduction to Bitcoin

merchants who accept bitcoins for both digital and physical goods and services. The price

of these goods and services is usually based on the exchange rate between Bitcoin and a

real-world currency, which can be found easily online (XE).

Typically, a user who wishes to spend bitcoins obtains it by exchanging real-world

currency for bitcoins. This can be achieved by purchasing bitcoins from a vending

machine, from an exchange, or simply from another person. Bitcoin vending machines,

often called "ATMs," are the most convenient way to buy bitcoins, because one can eas-

ily insert cash into a machine to obtain bitcoins instantly (Ulm, 2014 ). Bitcoin exchanges

are also a popular means to obtain bitcoins, but users often face a time delay while waiting

for bank transfers to clear (Ulm, 2014 ). Trading real-world cash for bitcoins is also a pos-

sibility but it is inconvenient if bitcoins are needed on the spot. However, marketplace

websites like LocalBitcoins have sprouted up to connect people interested in buying and

selling bitcoins to enable them to do so privately, whether in person or online

(LocalBitcoins ). This option is more likely to be used in countries with restricted or

no access to Bitcoin vending machines or exchanges.

Bitcoins are typically stored in a wallet, so a user needs to have a wallet available to buy

and sell bitcoins. Specifically, it is the private keys that are stored in a wallet (CoinDesk,

2014). These keys are used to access the Bitcoin addresses and sign transactions and there-

fore must be kept securely. There are various types of Bitcoin wallets, including desktop,

mobile, webs, and hardware wallets.

Users who choose to install a desktop wallet on their computer can create and keep

wallets on their computer. The original Bitcoin client software, known as Bitcoin Core,

which is still in use today, includes the functionality of creating a bitcoin address to send

and receive bitcoins and to store the corresponding private key for that address. There are

various other wallet software in which users may elect to install on their computer, like

the cross-platform MultiBit and the security-conscious Armory (Bitcoin.org ). The dif-

ferent wallet software have varying additional features, although the most basic function

of a wallet in storing the private keys for corresponding bitcoin addresses remains the

same. While the user maintains control of his desktop wallet at all times, such wallets,

like any other computer file, are vulnerable to theft by malicious users or software.

Desktop wallets are not the be-all and end-all of wallets, even if they were the first.

When transacting at a physical store, a mobile wallet is often the most convenient way to

spend some bitcoins. Mobile wallets are simply an application that provides for Bitcoin

wallet functionality in a mobile phone. There are apps like Bitcoin Wallet and Mycelium

that only exist on the mobile platform, while some desktop wallets like Blockchain.info

also have mobile versions (Bitcoin.org ). However, in the early 2014, Apple removed

Bitcoin Wallet apps like Blockchain.info from its App Store (Southurst, 2014 ), although

unofficial versions and mobile browser-based wallets continue to exist.

Another convenient type of wallet is the online wallet, which is generally accessible

from anywhere through a browser with an Internet connection, regardless of the device

18 Handbook of Digital Currency

used (CoinDesk, 2014 ). The private keys for a user's Bitcoin addresses are kept and stored

by the service provider of the online wallet, which may present a risk of the service pro-

vider or a third party absconding with the bitcoins, if security was not implemented prop-

erly. Blockchain.info also has a popular web-based online wallet and some online wallets

offer extra encryption and two-factor authentication for additional security.

Finally, there is small but growing interest in hardware wallets, which are specialized

devices that can hold keys electronically and are also able to send and receive bitcoins. An

example of a dedicated Bitcoin device is the Trezor, a single-purpose token-sized device

for making secure Bitcoin transactions (SatoshiLabs).

1.4.5 Mining to create new bitcoins and process transactions

Bitcoin is designed with a hard limit of 21 million bitcoins, which are expected to be

created by 2040 (Figure 1.3 ). For now, these bitcoins are generated through mining, dur-

ing which miners, who are Bitcoin users running software on specialized hardware, pro-

cess transactions and are rewarded with new bitcoins for contributing their computer

power to maintain the network. Mining is important not only for new bitcoins to be

issued but also because it is a necessary process for transactions to be added onto the

blockchain and be subsequently confirmed. The verification process is a computationally

intensive process that ensures that only legitimate transactions are verified and recorded

onto the blockchain. It is the network that provides the computing power for the trans-

actions to take place and for the transactions to be recorded.

What happens during mining is actually a mathematical process. A real-life analogy

to bitcoin mining would be the search for prime numbers: while it was easy to find the

small ones, it became increasingly more difficult to find the larger numbers, leading

researchers to use special high-performance computers to find them (Tindell, 2013).

2009

2.63

5.25

7.88

10.50

13.13

15.75

18.38

Total bitcoins in circulation over time (millions)

21.00

2013 2017 2021 2025 2029 2033

Figure 1.3 Bitcoin supply.

Introduction to Bitcoin

Mining is a computationally intensive task that requires miners to find the solution to a

predetermined mathematical problem in order to create a new block. This is the mathe-

matical proof of work. Mining is difficult because besides ensuring that the transactions are

valid, miners have to fit the data in a particular manner in order to add it to the blockchain.

Miners have to guess and search for a sequence of data that produces a required pattern.

The difficulty of the problem is automatically adjusted so that a new block can only be

created every 10 min on average. The Bitcoin protocol is designed to generate new bit-

coins progressively, at a predictable but decreasing rate. To ensure a progressive growth

in new bitcoins, the reward for solving a block is halved automatically every 4 years,

and the difficulty of solving increases over time. These two effects work together to pro-

duce an effect that over time, the rate at which bitcoins are produced will be similar to the

production rate of a commodity like gold (see Figure 1.3).Therewillbeapointinthe

future when the hard limit of bitcoins will be reached and the incentive for miners will

instead be transaction fees. The arbitrary number chosen to be the limit in number of bit-

coins is 21 million. Once the very last bitcoin, or to be specific, the very last satoshi—

0.00000001 of a bitcoin—is produced through mining, miners who continue to contribute

their computing power to verify transactions will instead berewarded with transaction fees.

This may be a less desirable situation for people and businesses relying on bitcoin payments,

which will have to pay a transaction fee, but it ensures that miners will still have an incentive

to keep the network up and running even after the last bitcoin is mined.

Every new block that is successfully added onto the blockchain references the previous

block, making it exponentially difficult to reverse previous transactions in previous blocks.

Because changing a block on the blockchain will require recalculation of the proofs of work

of all subsequent blocks (Bitcoin Project), it becomes more and more infeasible for an

adversary to manipulate a block after more blocks have been added after it, and the Bitcoin

protocol is accordingly designed to prefer longer chains. Miners therefore perform a vital

task as they verify transactions and ensure that the blockchain cannot be tampered with.

While bitcoin transfers are broadcast instantaneously over the network, there is, in

practice, a 10 min delay for a transaction to be confirmed. This is the result of the

10 min delay for a block to be created and added onto the blockchain. Having a confir-

mation ensures that the network (of miners) has verified that the bitcoins are valid and

have not been already spent. Typically, most users wait for six confirmations, that is, an

hour, before considering a transaction to be "confirmed," but each user has the freedom

to decide how long they wish to wait before they consider their transaction confirmed.

1.4.6 Security and cryptography

The security of the technology used is supported using secure hash algorithms and has a

good track record. The Bitcoin protocol is an open-source and is continuously improved

by the developer community subject to consensus among all network users. The hash

20 Handbook of Digital Currency

function mainly used in Bitcoin is SHA-256 (Pacia, 2013), which was incidentally originally

because the SHA algorithm is part of the public domain and has been extensively analyzed to

be secure (Pacia, 2013 ). SHA-256 is an upgrade from the SHA-1 series and is presently used

in Bitcoin for the digital signatures that secure the transactions and blockchain and it forms

thebasisoftheproof-of-workmathematicalproblem.

Central to Bitcoin technology is public-key cryptography, which with the SHA-256

hash function is used to generate Bitcoin addresses, sign transactions, and verify payments.

Public-key cryptography is a technique of reliably determining the authenticity of Bit-

coin transactions using digital signatures. It uses an asymmetrical algorithm that generates

two separate but asymmetrically linked keys: a public key and a private key. The keys are

asymmetrical in the sense that the public key is derived from the private key but it is com-

putationally impossible to obtain a private key from a public key. In such a system, the

public key is used to verify digital signatures in transactions while the private key is used to

sign transactions to produce those very digital signatures. The public key is publicly acces-

sible; in Bitcoin, it is used as the Bitcoin address to and from which payments are sent.

The private key, on the other hand, must be kept secret and safely. The beauty of such a

system is that transactions can be easily verified using the public key without sharing the

private key used to sign the transactions.

1.4.7 Pseudoanonymity

As seen from Figures 1.1 and 1.2 , a Bitcoin address is an alphanumeric sequence of char-

acters. There is no other information that can identify the sender and recipient of the

bitcoins. However, it is a common misconception to say that bitcoin is an anonymous

currency. This misconception often arises from a lack of understanding of the technology

(Brito and Castillo, 2013).

Prior to Bitcoin, online transactions have not been anywhere close to anonymous

because they have to go through third-party intermediaries, who have interests in know-

ing who their customers are, for risk assessment purposes and compliance with the rel-

evant laws and regulations. For example, when Alice makes a transfer of $10 using PayPal

to Bob, PayPal will have a record of the transfer. In addition, their PayPal accounts are

likely to be linked to their respective credit cards or bank accounts, which will provide

information as to their identities. On the other hand, if Alice gives Bob $10 in cash in

person, there is neither an intermediary nor a record of the transaction. If the two of them

do not know each other, then the transaction can be said to be completely anonymous.

Bitcoin is somewhere in between these two extremes. Bitcoins can be said to be like

cash in the sense that when Alice gives bitcoins to Bob, she no longer has them, while

Bob does. Since there is no third-party intermediary, nobody knows their identities as

well. However, unlike cash, the transaction is recorded on the blockchain. Some of

21 Introduction to Bitcoin

the information recorded includes the public keys of the sender and recipient, the

amount, and a time stamp. Every transaction in the history of bitcoin has been recorded

and will be recorded on the blockchain and is publicly viewable.

While there is some privacy, the blockchain is a public record of all transactions and it

may be possible for anyone to identify the parties behind them, especially if a person's

identity is linked to a public key. While bitcoins may be anonymous like cash in the sense

that parties can transact without disclosing their identities, it is also unlike cash because

transactions to and from any Bitcoin address can be traced. Therefore, Bitcoin is pseu-

donymous, not anonymous.

It is not particularly difficult for anyone with the right tools and access to join the dots

between a pseudonymous Bitcoin address and a real-world identity. Some personally

identifiable information is often captured during a transaction on a website, like an IP

address. To make it more difficult to connect an identity to a Bitcoin address, one would

have to use software methods that obfuscate or shield such personally identifiable infor-

mation from being tied to Bitcoin addresses.

Early studies have already shown some potential analyses that could erode the pseudo-

nymity of Bitcoin. For those who are persistent in connecting Bitcoin addresses to real-

world identities, their work should begin with the blockchain. In a simulated experiment,

a study found that up to 40% of Bitcoin users within the experiment could be personally

identified using behavior-based clustering methods (Androulaki et al., 2012). The statistical

properties of the transaction graph could also, with the relevant analysis, reveal the activity

and identity of Bitcoin users (Reid and Harrigan, 2013). Even the use of multiple public

keys may not defend against such transaction graph analysis (Ober et al., 2013), as an

observer may gradually be able discern patterns in user behavior to link the public keys

together, using a process called entity merging (Brito and Castillo, 2013).

Besides the technical aspects of Bitcoin, it is important to also consider the pressures

faced by Bitcoin intermediaries from regulators. Bitcoin regulation is evolving, and

should Bitcoin intermediaries become regulated, it is expected that anonymity will

become less guaranteed (Brito and Castillo, 2013 ), often with KYC and reporting

requirements requiring these intermediaries to collect personally identifiable information

from their customers.

1.5 BENEFITS AND RISKS

Bitcoin as a novel technology brings a range of benefits and risks to the table. This section

outlines some of the most well-known benefits and risks.

1.5.1 Freedom of payments

Bitcoin was specifically designed for fast transactions at low costs (Nakamoto, 2008 ). Pay-

ments can be processed with little or no fees, with the sender having the option to include

22 Handbook of Digital Currency

a transaction fee for faster confirmations. A low transaction cost is possible because there is

no single third-party intermediary. In addition to the lack of restrictions on transactions,

users have full control of their bitcoins and the freedom to send and receive bitcoins any-

time, anywhere, and to and from anyone.

Users may also choose to use Bitcoin to make fast cross-border transfers easily without

paying expensive fees for remittances. There is great potential for remittances because the

value of remittances, especially from people in developed countries to those in develop-

ing countries, is expected to increase to USD515 billion in 2015 (World Bank Payment

Systems Development Group, 2013). The reduced costs of remittances could be substan-

tial if remitted using bitcoins.

1.5.2 Merchant benefits

Bitcoin presents an alternative to the other methods of electronic payments accepted by

businesses. Traditional credit card acceptance is expensive for merchants, with customers

often having to pay for a merchant account and various fees for transactions, including but

not limited to transaction fees, interchange fees, and statement fees. These fees add up and

increase the costs of accepting credit cards for payments. Yet, merchants who forgo credit

card payments may lose business from customers used to the ease of paying with credit

cards. Not having to pay these expensive fees may allow businesses to pass on the cost

savings to consumers, benefiting everyone.

Bitcoin transactions are also secure, unlike credit card payments, which may use inse-

cure magnetic stripes and signatures, and are irreversible, unlike credit card payments,

which are subject to the possibility of fraudulent charge-backs. The low cost of transac-

tions also allows merchants to accept micropayments, paving the way for Bitcoin to be

widely accepted without a minimum transaction level.

1.5.3 User control

Each Bitcoin transaction can only be effected by the user who has the private key, putting

the user in full control of his bitcoins. Merchants cannot slip in unwanted charges later,

unlike credit cards that offer limited protection against such charges once an unethical

merchant has the card details. Transactions also do not contain substantial personal infor-

mation, which is at risk of leakage and theft.

However, the converse effect of full user control is the point that the private key con-

trols the access to one's bitcoins. Bitcoin, being a digital currency, brings specific security

challenges (Kaminsky, 2013 ). Perhaps the most important risk to end users is that if the

private key is lost, access to the bitcoins is irrecoverable. Poor wallet protection may leave

users vulnerable to thefts, especially by specially crafted malicious software designed to

steal bitcoins (Doherty, 2011 ). Bitcoin users should therefore be security conscious with

Bitcoin, just as they do for other financial activities (Brito and Castillo, 2013).

23 Introduction to Bitcoin

1.5.4 Platform for further innovation

The Bitcoin protocol may, in its original form, work as a payment network, but it has the

potential for further innovation. What actually happens in the Bitcoin network is that

data in the form of Bitcoin transactions are broadcasted and verified before being kept

on the blockchain. Bitcoin technology may therefore be adapted for the transfer of other

types of data, like stocks or bets (Brito, 2013 ). Feature layers are beginning to be built on

top of Bitcoin, which include smart property and assurance contracts (Brito and Castillo,

2013). Being an open-source technology, alternative digital currencies like Litecoin and

Dogecoin, among others, have also emerged to suit different objectives.

1.5.5 Internal change and volatility

As a community-driven project, Bitcoin continues to undergo changes as software devel-

opers improve and change the software with consensus of network users. At the same

time, the price of bitcoins continues to fluctuate as current events affect the price. Some

significant price changes are said to resemble a traditional speculative bubble, which may

occur when optimistic media coverage attracts investors (Salmon, 2013 ). This may make

it difficult to determine how good bitcoins are as a store of value, and merchants accept-

ing bitcoins therefore often convert them out into fiat currency very quickly. It is also

difficult to predict the Bitcoin economy in the future as it is the first widely accessible

cryptocurrency, although researchers are already working on models that will attempt

to explain behavior in the Bitcoin world. At the same time, it may be possible that

the value of bitcoins may become less volatile as familiarity with Bitcoin increases

with time.

1.5.6 Facilitation of criminal activity

With the pseudoanonymity and ease of payments offered by Bitcoin, it is no wonder that

governments are concerned with the use of Bitcoin in facilitating criminal activity.

Indeed, one of the most well-known criminal uses of Bitcoin was on the Silk Road web-

site, a black market often used to trade illicit drugs and counterfeit passports. Silk Road

used a combination of Bitcoin payments and the anonymizing network Tor to create a

marketplace for such illicit goods and services (Chen, 2011 ). Another major concern

regarding Bitcoin is its use to launder money and finance terrorist activity. These con-

cerns were stoked especially after the Liberty Reserve, a private and centralized digital

currency was shut down on money laundering concerns (BBC News, 2013 ). It is impor-

tant to remember, however, that bitcoins are like money, and money can be used for

both lawful and unlawful purposes. Other methods of transferring money have been used

for financing crimes and money laundering even before Bitcoin existed. However, many

Bitcoin exchanges are beginning to employ antimoney laundering features that include

24 Handbook of Digital Currency

keeping records of their customers, which will reduce the attractiveness of Bitcoin to

criminals.

Bitcoin, however, also offers benefits over traditional money that protect against some

forms of financial crime. For example, the mining process of verifying transactions, which

solves the double-spending problem, makes it extremely difficult for bitcoins to be

double-spent or counterfeited. An adversary needs to amass sufficient computing power

to overcome the combined network computing power in order to be able to attempt to

modify present and future transactions before the rest of the network catches up.

1.5.7 Legal regulatory attitude

As Bitcoin is novel, its regulation by governments run the gamut of being permissive to

outright bans. The regulatory landscape continues to change as governments grapple

with the risks and benefits of Bitcoin to their country. For a start, regulators in some juris-

dictions are beginning to provide rules and guidance on the treatment of digital curren-

cies in their country, especially in measures relating to antimoney laundering and the

countering of terrorist financing, as well as taxes. The challenge for regulators is to

encourage beneficial uses and future innovations while minimizing the risks posed

and to do so without preventing such innovations from spawning.

1.5.8 Economic risk

Bitcoin is something that is very different from the existing financial system for which

country regulators have experience regulating. The innovative use of Bitcoin may be dis-

ruptive to the financial and payment markets in that Bitcoin, for example, can scale up to

replace money transmission and card payment services, or even stock exchanges, which

renders the incumbent service providers obsolete. If these changes occur rapidly, there is

a risk that this will destabilize the financial and payment markets and ultimately price

stability in a market.

1.6 IMPACT OF THE DIGITAL CURRENCY REVOLUTION

The digital currency revolution will have a lot of impact on the digital and physical world.

A lot of devices will be connected to each other via near-field communication (NFC).

Devices that are carried by our side or are worn on our body will contain information

about our preferences, possibly our current state of health and most likely all our personal

records including how much money we have. We may not need to carry physical wallets

and identity cards anymore.

These devices will monitor us and improve our experience in every aspect of our life

including medical care, education, and financial services. The blockchain technology can

play a major role in lowering the cost of financial services via cost sharing through min-

ing, and therefore, financial institutions can reach out to the unbanked and underbanked,

25 Introduction to Bitcoin

as well as those that require lending and fund raising. All these can be done via the peer-

to-peer network of cryptocurrency, either decentralized or distributed. Financial services

especially banking will likely be disrupted and margin will be affected as what eCash was

set out to do in the early 1990s.

A second example is the use of smart contract for a sharing economy. We will be able

to share our assets such as cars, hard disks, and computer memory that we do not use and

rent them out to others for a fee. Smart contracts via the distributed peer-to-peer network

will make all these possible in the future. This will ensure that infrastructure need not

increase but excess capacity is used efficiently.

The desire to own entire assets will be less as more peer-to-peer digital assets or digital

trusts can be held by the crowd via blockchain technology. There is also the possibility of

time banking so that the cryptocurrency is stored in hours of work. One can then trade

with the time spent in, say, palliative care when one is young, and then, the same person

will be entitled to such care when he or she gets older with the hours that have been

deposited. While these can be done with a centralized system, a distributed or decentra-

lized blockchain system has unique advantages especially in terms of distributed comput-

ing. Cryptocurrency may not replace the fiat currency, but its blockchain technology will

certainly have an impact on the welfare of the people and perhaps even out the inequality.

1.7 CONDITIONS FOR A SUCCESSFUL CRYPTOCURRENCY

1.7.1 Ecosystem

There is always the first-mover advantage and Bitcoin has certainly emerged as the lead-

ing cryptocurrency with an estimated 6 million electronic wallets, 70,000 merchants, and

a market capitalization of USD5 billion. For the 6 months leading to October 2014, there

were 50-80k transactions daily, and approximately USD50 million (equivalent to over

110,000 bitcoins in 2014) are traded daily. The number of wallets is small given that

we have more than 7 billion people in the world. Bitcoin has been successful so far

and an ecosystem is up to support its existence. Even though the network effect is kicking

in, there is still a long way to go.

A successful digital currency must be able to ride on its initial success and leverage on

the network effect. The more people use the coin, the more valuable it will become. As it

becomes more valuable, the reward for mining will increase, and more miners will join in

the competitive accounting exercise. Bitcoin is subject to the same problems we men-

tioned earlier.

1.7.2 Incentives

As the mining costs go up because equipment becomes more expensive, mining pools

will be formed as miners are usually risk averse and want better odds in winning the

race. This increases the possibility of an attack or the emergence of a gold finger that

26 Handbook of Digital Currency

determines to cause problems. There are slightly over 13.4 million bitcoins in circulation

as of October 2014. Twenty-five bitcoins are created approximately every 10 min from

2013 to 2016 and the number of new coins created will halve every 4 years.

As soon as the full supply of 21 million bitcoins are issued by the year 2040, which is

still very distant, the risk of miners dropping out may increase. If the only reward is trans-

action fees and if fees become too high, the merchants are likely to drop out.

Of course, there are technical solutions to all these and some cryptocurrencies have

come up with the idea of proof of stake reducing the probability that any single person

can use a quantum computer to overwrite the whole system. There are also attempts to

lower the cost of mining so as to reduce the so-called 51% attack or gold finger problem.

However, there is still no fool proof solution to the gold finger issue that if anyone with

enough financial strength wishes to mess up the record, he or she can theoretically do it.

1.7.3 Identification

There are also cryptocurrencies that are looking into proof of identity to reduce the pos-

sibility of using the currency for money laundering or terrorism activities. If that problem

can be resolved, cryptocurrency has a very real potential to be very popular.

If a particular cryptocurrency is able to accept that the government is part of the eco-

system and its community engages with the government meaningfully in creating the

ecosystem, that cryptocurrency is likely to become more widely accepted. Given that

most of the welfare improvement comes from the bottom of the wealth pyramid, emerg-

ing markets have the upper hand in harnessing the low-hanging fruits of cryptocurrency

via a decentralized but not necessary distributed system. A cryptocurrency that addresses

those issues mentioned will have a bright future.

1.8 FUTURE PROSPECTS AND CONCLUSION

Many people see similarities between the growth of the Internet and the growth of cryp-

tocurrency and postulate that cryptocurrency is going to see exponential growth like the

Internet. However, from the business perspective, the growth of the Internet has more to

do with e-commerce and less to do with finance. On the other hand, with cryptocur-

rency, for once in the history of mankind, technology is playing a leading role in finance.

In future, one should expect a bank to be a digital or technologically savvy bank. The

disruptive force has now arrived at the door step of finance and the blockchain technol-

ogy is one of the solutions.

There are also similarities between hedge funds and cryptocurrency at the industry

level. When the hedge fund industry was in its infant stage, it was perceived to be dis-

ruptive to the currency system because hedge fund managers were perceived as the bad

guys who took big bets. They were seen to be the mavericks who attacked the currency

system and caused the stock markets to collapse. Some banks did not want to deal with

27 Introduction to Bitcoin

them as it did not make business sense with the high compliance costs. Start-ups in cryp-

tocurrency today face the same problems.

There is a lot of bad press and misunderstanding in the media regarding cryptocur-

rency and some banks are unwilling to open accounts with cryptocurrency start-ups

because of various reasons. Regulators are also generally uncomfortable at the moment

to deal with a financial innovation as complex as Bitcoin or indeed any other cryptocur-

rency. At the same time, there is a general resistance and reluctance by Main Street to

learn about the intricacies of this financial innovation—it is a wait-and-see situation. That

is human nature and it is always the universities and those who are interested in the tech-

nology who will see the opportunities first.

There are a lot of similarities between cryptocurrency and hedge fund strategies that

were inherently quantitative and difficult to understand. It was no surprise to anyone

that hedge fund strategies were initially embraced by the university endowment funds

that were less constrained than the traditional managers. Again, universities and financial

entrepreneurs will be the first to embrace the cryptocurrency technology before it spills

over to the main street.

Cryptocurrency is here to stay and will evolve over time. If Bitcoin loses its popularity

for whatever reason, a new cryptocurrency will emerge to replace it with better features.

Countries with huge debts have the incentive to create their own cryptocurrency and

those who wish to promote financial integration may also turn to cryptocurrency, simply

because the cost is low in creating a decentralized partially distributed system. There will

be welfare improvement in a cryptocurrency world, which is decentralized but not nec-

essary fully distributed, with proof of identity, proof of stake, and the flexibility to incor-

porate smart contracts for a sharing economy.

Eventually, it is about reduction of business cost, and welfare improvement will fol-

low for those at the bottom of the wealth pyramid. Eventually, all of this will lead to

enhanced efficiency in a sharing economy. The outlook on the development of crypto-

currency is much more optimistic because of the blockchain technology. We are likely to

see a great leap in its use, with NFC and related mobile technology being the driver

behind its boom. At the same time, it is difficult to predict if cryptocurrency is the next

big thing as there is still a lot of uncertainty in the cryptocurrency world. But it is a tech-

nology that financial institutions cannot ignore.

In conclusion, Bitcoin is a novel invention, which is a breakthrough in terms of the

payments and decentralized networks we know today. It brings with it various benefits

and risks that users should be cognizant and indeed conversant with should they wish to

deal with and in bitcoins. This chapter has mainly discussed the main features of Bitcoin,

but other cryptocurrencies are likely to have similar features and a clear understanding of

Bitcoin will aid in understanding other cryptocurrencies. It is only with a good founda-

tion in the knowledge of this amazing new technology that we will be able to use it to its

fullest potential without fear.

28 Handbook of Digital Currency

ACKNOWLEDGMENTS

The ideas for this chapter originated from the expertise of David Lee, especially in his introductory lectures

on Bitcoin, and from Lam Pak Nian's earlier research on Bitcoin during his undergraduate degree. The

authors also wish to thank Nirupamadevi Bhaskar for clarifying some of the basic concepts and for her guid-

ance on interpreting the raw transaction data.

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30 Handbook of Digital Currency

... Cryptocurrencies are subsets of the digital currencies [1] which gained prominence as an important type of digital currency during recent years. It has also become a new investment option for investors and trading in these cryptocurrencies have become colossal. ...

Cryptocurrencies are sub-classes of digital currencies. Trading of these currencies have gained momentum during the past few years and have become new investment avenues for investors. An understanding on the market anomalies, which are patterns in asset prices would help the investors to adopt suitable strategies while trading in this asset class. This study aims to examine the presence of three calendar anomalies, day of the week, turn of the month, and year end effect in the cryptocurrencies. The top five cryptocurrencies which constitute a major share of the market capitalization value are selected for the study and the period of study is from July 23, 2017 to July 9, 2020. Dummy Variable Regression using GARCH (1, 1) model was employed on the log value of returns of the cryptocurrencies. The study provides evidence on the existence of anomalies during Thursdays, the months March and April, and at the turn of the year.

... The technology provides an infrastructure for maintaining a public accounting ledger and for processing transactions with no central authority. Unlike traditional currencies, which rely on central banks, bitcoin relies on a decentralized computer network to validate transactions and grow money supply (see Yermack (2015) and Yermack (2017) for further background on the bitcoin and its technology). Each bitcoin is effectively a (divisible) unit, which is transferred between pseudonymous addresses through this network. ...

Shaun De Silva
S B Goyal
Pradeep Bedi

Physical payment collection is creating a lot of safety and security challenges to handle payment collection in real-life scenarios. Digital currency has become a preferable choice in the 21st century for business transactions for payment collection. People are not aware about the utilization of digital currencies working principles & types and other digital currency integration with blockchain. We have discussed some of the digital currency system based applications that exist in today's world, challenge faces within these applications and their security weakness within this conference paper. Proposed solution will help to boost customer confidence toward the digital currency system, enabling some methods of data transmission control and offer guidelines toward the selection process. Case study on other countries uses on the system as well as discussion between the non blockchain based and blockchain based digital currency system in order to better understand the advancement of digital currency system.

Several confluences of technological, economic and sociocultural phenomena, that are currently shifting conventional forms of commercial exchanges (Ertz et al., 2019a). This article discusses an exemplification of this supposed reconfiguration of commercial exchange (Ertz et al., 2019a). The study explores how the two societal phenomena of the collaborative economy (CE) and the blockchain technology (BT), both resulting markedly from technological advances and economic disturbances, intersect to reorganize and rearrange commercial exchanges. Although having almost become a vernacular concept, the CE is an economic model that has taken on an unprecedented scale and scope through technological advances (Roos and Hahn, 2019). It has resulted in demultiplying peer-to-peer (P2P), peer-to-organization (P2O) and organization-to-peer (O2P) exchanges (Ertz et al., 2016). Other major developments in computer sciences and in mathematics have led to the emergence of the blockchain technology (Ghilal and Nach, 2019). This technology has led to an intensification of more genuine P2P exchanges with limited intermediation. Despite connections between both blockchain technology and the CE, in terms of technological advances and facilitation of peer-to-peer exchanges, few studies have examined the intertwining of both phenomena. Since the literature on this subject remains sparse, the objective of this article is to examine current information on the subject in order to understand the role played by blockchain technology in the development of collaborative practices. This study adopts an exploratory descriptive design for its ability to provide a preliminary understanding of new and poorly documented phenomena. In addition, this design provides a frame for the formulation of new ideas and hypotheses. Since studies conducted on the topic of the CE and the blockchain technology are relatively recent, this article also aims at gathering state of the art research on the use of blockchain technology in order to understand its potential implication within collaborative practices. This technology may have the potential to act as a catalyst of the development of the CE by further decentralizing transactions and exchanges. Blockchain technology may therefore spur impacts on the diffusion of this new socioeconomic model known as the CE while also giving rise to a reconfiguration of existing actors, systems and roles. Since the impacts of blockchain technology on the development of the CE remains largely unexplored, the present study seeks to fill this theoretically and practically relevant gap by setting the following two objectives: 1) Define and conceptualize blockchain technology in the collaborative economy sphere; 2) Explore the potential implications of blockchain technology for the collaborative economy. The contributions of this exploratory study are twofold. First, the paper provides a literature review that encapsulates the concepts of cryptocurrencies, blockchain technology and the CE. Second, the study results in the development of a theory-based research agenda to spur future research on the subject.

Myriam Ertz
Emilie Boily

This study highlights the potential impacts of blockchain technology on the collaborative economy (CE), colloquially known as the sharing economy. This conceptual review first analyzes how the CE intersects with the blockchain technology. Collaborative consumption involves an intensification of peer-to-peer trade, underpinned by robust digital infrastructures and processes, hence an increased use of new technologies and a redefinition of business activities. As an inherently connected economy, the CE is, therefore, prone to integrating the most recent technological advances including artificial intelligence, big data analysis, augmented reality, the smart grid, and blockchain technology. This review then furthers the examination of the organizational and managerial implications related to the use of blockchain technology in terms of governance, transaction costs, and user confidence. A closing case finally examines the role of a prominent social networking site (i.e., Facebook) in the CE-blockchain nexus. Keywords: Blockchain technology, Collaborative economy, Cryptocurrency, Social networking site, Business, Governance, Trust, Digital economy

Cette étude présente les impacts potentiels de la technologie de la chaîne de blocs sur l'économiecollaborative. L'article se divise en deux grandes parties, toutes deux issues du croisement entre l'économiecollaborative et la technologie de la chaîne de blocs. La première partie s'intéresse à la consommation collaborative, caractérisée par un accroissement des échanges de pair à pair, par une utilisation accrue des nouvelles technologies et par une redéfinition des activités commerciales, tandis que la seconde partie examine les implications organisationnelles et managériales de la chaîne de blocs pour la gouvernance, pour les coûts detransaction et pour la confiance des usagers.

Dhanalakshmi Senthilkumar

Blockchain is the process of development in bitcoin. It's a digitized, decentralized, distributed ledger of cryptocurrency transactions. The central authorities secure that transaction with other users to validate transactions and record data, data is encrypted and immutable format with secured manner. The cryptography systems make use for securing the process of recording transactions in private and public key pair with ensuring secrecy and authenticity. Ensuring bitcoin transaction, to be processed in network, and ensuring transaction used for elliptic curve digital signature algorithm, all transactions are valid and in chronological order. The blockchain systems potential to transform financial and model of governance. In Blockchain, databases hold their information in an encrypted state, that only the private keys must be kept, so these AI algorithms are expected to increasingly be used, whether financial transactions are fraudulent, and should be blocked or investigated.

Jerry Brito
Andrea Castillo

Bitcoin is the world's first completely decentralized digital currency. This paper will provide a short introduction to the Bitcoin network, including its properties, operations, and pseudonymous character. It will describe the benefits of allowing the Bitcoin network to develop and innovate, while highlighting issues of concern for consumers, policymakers, and regulators. It will describe the current regulatory landscape and explore other potential regulations that could be promulgated. The paper will conclude by providing policy recommendations that will assuage policymakers' common concerns while allowing for innovation within the Bitcoin network.

Fergal Reid
Martin Harrigan

Anonymity in Bitcoin, a peer-to-peer electronic currency system, is a complicated issue. Within the system, users are identified by public-keys only. An attacker wishing to de-anonymize its users will attempt to construct the one-to-many mapping between users and public-keys and associate information external to the system with the users. Bitcoin tries to prevent this attack by storing the mapping of a user to his or her public-keys on that user's node only and by allowing each user to generate as many public-keys as required. In this chapter we consider the topological structure of two networks derived from Bitcoin's public transaction history. We show that the two networks have a non-trivial topological structure, provide complementary views of the Bitcoin system and have implications for anonymity. We combine these structures with external information and techniques such as context discovery and flow analysis to investigate an alleged theft of Bitcoins, which, at the time of the theft, had a market value of approximately half a million U.S. dollars.

Adam Back

Hashcash was originally proposed as a mechanism to throttle systematic abuse of un-metered internet resources such as email, and anonymous remailers in May 1997. Five years on, this paper captures in one place the various applications, improvements suggested and related subsequent publications, and describes initial experience from experiments using hashcash.

Micha Ober
Stefan Katzenbeisser
Kay Hamacher

The Bitcoin network of decentralized payment transactions has attracted a lot of attention from both Internet users and researchers in recent years. Bitcoin utilizes a peer-to-peer network to issue anonymous payment transactions between different users. In the currently used Bitcoin clients, the full transaction history is available at each node of the network to prevent double spending without the need for a central authority, forming a valuable source for empirical research on network structure, network dynamics, and the implied anonymity challenges, as well as guidance on the future evolution of complex payment systems. We found dynamical effects of which some increase anonymity while others decrease it. Most importantly, several parameters of the Bitcoin transaction graph seem to have become stationary over the last 12-18 months. We discuss the implications.

Garrick Hileman

The rise of Bitcoin has led to renewed interest in alternative currencies. While alternative currencies have regularly featured on the economic landscape over the last half-millennia we have a limited understanding of several salient questions, such as which factors explain their rise and decline. An alternative currency is considered here to be any medium of exchange other than legal tender. A new taxonomy is introduced below to more precisely define the many different types of alternative currencies and to address the disparate lexicon found in the literature. Alternative currencies can be broadly classified as either tangible (Table 1) or digital (Table 2).

Nikolei M. Kaplanov

This Comment explores the lawfulness of using bitcoin, a privately-issued currency transacted on a peer-to-peer network, and the ability of the federal government to bar transactions between two willing parties. While there are no cases yet challenging the ability of parties in the United States to make transactions using bitcoins, there are policymakers who have denounced the use of bitcoin. This has led to the question of whether the federal government has the ability under current federal law to prohibit the use of bitcoins between willing parties. This Comment will show that the federal government has no basis to stop bitcoin users who engage in traditional consumer purchases and transfers. This Comment further argues that the federal government should refrain from passing any laws or regulations limiting the use of bitcoins. Should any claim arise, this Comment argues that there is a perfectly acceptable model with which to analogize bitcoin use: community currencies.

Satoshi Nakamoto

A purely peer-to-peer version of electronic cash would allow online payments to be sent directly from one party to another without going through a financial institution. Digital signatures provide part of the solution, but the main benefits are lost if a trusted third party is still required to prevent double-spending. We propose a solution to the double-spending problem using a peer-to-peer network. The network timestamps transactions by hashing them into an ongoing chain of hash-based proof-of-work, forming a record that cannot be changed without redoing the proof-of-work. The longest chain not only serves as proof of the sequence of events witnessed, but proof that it came from the largest pool of CPU power. As long as a majority of CPU power is controlled by nodes that are not cooperating to attack the network, they'll generate the longest chain and outpace attackers. The network itself requires minimal structure. Messages are broadcast on a best effort basis, and nodes can leave and rejoin the network at will, accepting the longest proof-of-work chain as proof of what happened while they were gone.

David Chaum

Automation of the way we pay for goods and services is already underway, as can be seen by the variety and growth of electronic banking services available to consumers. The ultimate structure of the new electronic payments system may have a substantial impact on personal privacy as well as on the nature and extent of criminal use of payments. Ideally a new payments system should address both of these seemingly conflicting sets of concerns.

Evaluating user privacy in bitcoin. IACR Cryptology ePrint Archive 596

E Androulaki

Androulaki, E., et al., 2012. Evaluating user privacy in bitcoin. IACR Cryptology ePrint Archive 596. Retrieved from http://fc13.ifca.ai/proc/1-3.pdf.

Source: https://www.researchgate.net/publication/306945638_Handbook_of_Digital_Currency

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