Cryptocurrency

Overview

Cryptocurrency is a type of digital asset that uses distributed ledger, or blockchain, technology to enable a secure transaction. Individual coin ownership records are stored in a digital ledger or blockchain, which is a computerized database that uses a consensus mechanism to secure transaction records, control the creation of additional coins, and verify the transfer of coin ownership. The two most common consensus mechanisms are proof of work and proof of stake. Despite the name, which has come to describe many of the fungible blockchain tokens that have been created, cryptocurrencies are not considered to be currencies in the traditional sense, and varying legal treatments have been applied to them in various jurisdictions, including classification as commodities, securities, and currencies. Cryptocurrencies are generally viewed as a distinct asset class in practice.

History

In 1983, American cryptographer David Chaum conceived of a type of cryptographic electronic money called ecash. Later, in 1995, he implemented it through Digicash, an early form of cryptographic electronic payments. Digicash required user software in order to withdraw notes from a bank and designate specific encrypted keys before they could be sent to a recipient. This allowed the digital currency to be untraceable by a third party. In 1996, the National Security Agency published a paper entitled How to Make a Mint: The Cryptography of Anonymous Electronic Cash, describing a cryptocurrency system. The paper was first published in an MIT mailing list (October 1996) and later (April 1997) in The American Law Review. In 1998, Wei Dai described "b-money," an anonymous, distributed electronic cash system. Shortly thereafter, Nick Szabo described bit gold. Like bitcoin and other later cryptocurrencies, bit gold was proposed as a digital currency system in which users would generate money by completing proof-of-work functions whose solutions were cryptographically chained and published. In January 2009, bitcoin was created by pseudonymous developer Satoshi Nakamoto. It used SHA-256, a cryptographic hash function, in its proof-of-work scheme. In April 2011, Namecoin was created as an attempt at forming a decentralized DNS. In October 2011, Litecoin was released, which used scrypt as its hash function instead of SHA-256. Peercoin, created in August 2012, used a hybrid of proof-of-work and proof-of-stake. Cryptocurrency has undergone several periods of growth and retraction, including several bubbles and market crashes, such as in 2011, 2013–2014/15, 2017–2018, and 2021–2023. In August 2014, the UK announced its Treasury had commissioned a study of cryptocurrencies and what role, if any, they could play in the UK economy. The study was also to report on whether regulation should be considered. Its final report was published in 2018, and it issued a consultation on cryptoassets and stablecoins in January 2021. In June 2021, El Salvador became the first country to accept bitcoin as legal tender, after the Legislative Assembly had voted 62–22 to pass a bill submitted by President Nayib Bukele classifying the cryptocurrency as such. In August 2021, Cuba followed with Resolution 215 to recognize and regulate cryptocurrencies such as bitcoin. In September 2021, the government of China, the single largest market for cryptocurrency, declared all cryptocurrency transactions illegal. This completed a crackdown on cryptocurrency that had previously banned the operation of intermediaries and miners within China. In September 2022, the world's second largest cryptocurrency at that time, Ethereum, transitioned its consensus mechanism from proof-of-work (PoW) to proof-of-stake (PoS) in an upgrade process known as "the Merge". According to the Ethereum Founder, the upgrade would cut both Ethereum's energy use and carbon-dioxide emissions by 99.9%. On 11 November 2022, FTX Trading Ltd., a cryptocurrency exchange, which also operated a crypto hedge fund, and had been valued at $18 billion, filed for bankruptcy. The financial impact of the collapse extended beyond the immediate FTX customer base, as reported, while, at a Reuters conference, financial industry executives said that "regulators must step in to protect crypto investors." Technology analyst Avivah Litan commented on the cryptocurrency ecosystem that "everything...needs to improve dramatically in terms of user experience, controls, safety, customer service." An October 2024 survey from the Pew Research Center found that 63% of adults in the U.S. "have little to no confidence that current ways to invest in, trade or use cryptocurrencies are reliable and safe." The survey also reported that 17% of U.S. adults had directly interacted with cryptocurrency, which was statistically unchanged from 2021.

Terminology

The word "cryptocurrency", in its modern sense, was added to the Oxford English Dictionary in September 2018, with its earliest usage noted as being on Twitter in September 2009; its diminutive, crypto, was entered in 2022. In March 2018 cryptocurrency was added to the Merriam-Webster Dictionary.

Altcoins

After the early innovation of bitcoin in 2008 and the early network effect gained by bitcoin, tokens, cryptocurrencies, and other digital assets that were not bitcoin became collectively known during the 2010s as alternative cryptocurrencies, or "altcoins". Sometimes the term "alt coins" was used, or disparagingly, "shitcoins". Paul Vigna of The Wall Street Journal described altcoins in 2020 as "alternative versions of Bitcoin" given its role as the model protocol for cryptocurrency designers. A Polytechnic University of Catalonia thesis in 2021 used a broader description, including not only alternative versions of bitcoin but every cryptocurrency other than bitcoin. As of early 2020, there were more than 5,000 cryptocurrencies.

Altcoins often have underlying differences when compared to bitcoin. For example, Litecoin aims to process a block every 2.5 minutes, rather than bitcoin's 10 minutes which allows Litecoin to confirm transactions faster than bitcoin. Another example is Ethereum, which has smart contract functionality that allows decentralized applications to be run on its blockchain. Ethereum was the most used blockchain in 2020, according to Bloomberg News. In 2016, it had the largest "following" of any altcoin, according to the New York Times. Significant market price rallies across multiple altcoin markets are often referred to as an "altseason".

Stablecoins

Stablecoins are cryptocurrencies designed to maintain a stable level of purchasing power. Notably, these designs are not foolproof, as a number of stablecoins have crashed or lost their peg. For example, on 11 May 2022, Terra's stablecoin UST fell from $1 to 26 cents. The subsequent failure of Terraform Labs resulted in the loss of nearly $40B invested in the Terra and Luna coins. In September 2022, South Korean prosecutors requested the issuance of an Interpol Red Notice against the company's founder, Do Kwon. In Hong Kong, the expected regulatory framework for stablecoins in 2023/24 is being shaped and includes a few considerations.

Memecoins

Memecoins are a category of cryptocurrencies that originated from Internet memes or jokes. One example is Dogecoin, a memecoin featuring the Shiba Inu dog from the Doge meme. Donald Trump and his wife Melania are the subject of their own meme coins, both of which declined in value soon after launch. Memecoins are known for extreme volatility; for example, the record-high value for a Dogecoin was 73 cents, but that had plunged to 13 cents by mid-2024. Scams are prolific among memecoins.

Physical crypto

Physical cryptocurrency coins have been made as promotional items and some have become collectibles. Some of these have a private key embedded in them to access crypto worth a few dollars. There have also been attempts to issue bitcoin "bank notes". The term "physical bitcoin" is used in the finance industry when investment funds that hold crypto purchased from crypto exchanges put their crypto holdings in a specialised bank called a "custodian". These physical representations of cryptocurrency do not hold any value by themselves; these are only utilized for collectable purposes. For example, the first incarnation of the bitcoin Casascius, coins made of silver, brass or aluminum sometimes with gold plating, or Titan Bitcoin, which in silver or gold versions are sought after by numismatists.

Architecture

The underlying technical system upon which cryptocurrencies are based was created by Satoshi Nakamoto. Within a proof-of-work system such as bitcoin, the safety, integrity, and balance of ledgers are maintained by a community of mutually distrustful parties referred to as miners. Miners use their computers to help validate and timestamp transactions, adding them to the ledger in accordance with a particular timestamping scheme. In a proof-of-stake blockchain, transactions are validated by holders of the associated cryptocurrency, sometimes grouped together in stake pools. Most cryptocurrencies are designed to gradually decrease the production of that currency, placing a cap on the total amount of that currency that will ever be in circulation. Compared with ordinary currencies held by financial institutions or kept as cash on hand, cryptocurrencies can be more difficult for seizure by law enforcement.

Blockchain

The validity of each cryptocurrency's coins is provided by a blockchain. A blockchain is a continuously growing list of records, called blocks, which are linked and secured using cryptography. Each block typically contains a hash pointer as a link to a previous block, a timestamp, and transaction data. By design, blockchains are inherently resistant to modification of the data. A blockchain is "an open, distributed ledger that can record transactions between two parties efficiently and in a verifiable and permanent way". For use as a distributed ledger, a blockchain is typically managed by a peer-to-peer network collectively adhering to a protocol for validating new blocks. Once recorded, the data in any given block cannot be altered retroactively without the alteration of all subsequent blocks, which requires collusion of the network majority. Blockchains are secure by design and are an example of a distributed computing system with high Byzantine fault tolerance. Decentralized consensus has therefore been achieved with a blockchain.

Nodes

A "node" is a computer that connects to a cryptocurrency network. The node supports the cryptocurrency's network through either relaying transactions, validation, or hosting a copy of the blockchain. In terms of relaying transactions, each network computer (node) has a copy of the blockchain of the cryptocurrency it supports. When a transaction is made, the node creating the transaction broadcasts details of the transaction using encryption to other nodes throughout the node network so that the transaction (and every other transaction) is known. Node owners are either volunteers, those hosted by the organization or body developing the technology, or those incentivised by rewards from the node network.

Timestamping

Cryptocurrencies use various timestamping schemes to "prove" the validity of transactions added to the blockchain ledger without the need for a trusted third party. The first timestamping scheme invented was the proof-of-work scheme. The most widely used proof-of-work schemes are based on SHA-256 and scrypt. Some other hashing algorithms that are used for proof-of-work include CryptoNote, Blake, SHA-3, and X11. Another method is called the proof-of-stake scheme. Proof-of-stake is a method of securing a cryptocurrency network and achieving distributed consensus through requesting users to show ownership of a certain amount of currency. It is different from proof-of-work systems that run difficult hashing algorithms to validate electronic transactions. The scheme is largely dependent on the coin, and there is currently no standard form of it. Some cryptocurrencies use a combined proof-of-work and proof-of-stake scheme.

Mining

On a blockchain, mining is the validation of transactions. For this effort, successful miners obtain new cryptocurrency as a reward. The reward decreases transaction fees by creating a complementary incentive to contribute to the processing power of the network. The rate of generating hashes, which validate any transaction, has been increased by the use of specialized hardware such as FPGAs and ASICs running complex hashing algorithms like SHA-256 and scrypt. This arms race for cheaper-yet-efficient machines has existed since bitcoin was introduced in 2009. Mining is measured by hash rate, typically in TH/s. A 2023 IMF working paper found that crypto mining could generate 450 million tons of CO2 emissions by 2027, accounting for 0.7 percent of global emissions, or 1.2 percent of the world total. With more people entering the world of virtual currency, generating hashes for validation has become more complex over time, forcing miners to invest increasingly large sums of money to improve computing performance. Consequently, the reward for finding a hash has diminished and often does not justify the investment in equipment and cooling facilities (to mitigate the heat the equipment produces) and the electricity required to run them. Popular regions for mining include those with inexpensive electricity, a cold climate, and jurisdictions with clear and conducive regulations. By July 2019, bitcoin's electricity consumption was estimated to be approximately 7 gigawatts, around 0.2% of the global total, or equivalent to the energy consumed nationally by Switzerland. Some miners pool resources, sharing their processing power over a network to split the reward equally, according to the amount of work they contributed to the probability of finding a block. A "share" is awarded to members of the mining pool who present a valid partial proof-of-work. As of February 2018, the Chinese government has halted trading of virtual currency, banned initial coin offerings, and shut down mining. Many Chinese miners have since relocated to Canada and Texas. One company is operating data centers for mining operations at Canadian oil and gas field sites due to low gas prices. In June 2018, Hydro Quebec proposed to the provincial government to allocate 500 megawatts of power to crypto companies for mining. According to a February 2018 report from Fortune, Iceland has become a haven for cryptocurrency miners in part because of its cheap electricity. In March 2018, the city of Plattsburgh, New York put an 18-month moratorium on all cryptocurrency mining in an effort to preserve natural resources and the "character and direction" of the city. In 2021, Kazakhstan became the second-biggest crypto-currency mining country, producing 18.1% of the global exahash rate. The country built a compound containing 50,000 computers near Ekibastuz.