Monero (XMR) is an open-source cryptocurrency created in April 2014 that focuses on privacy and decentralization. Monero uses a public ledger to record transactions while new units are created through a process called mining.
|Original author(s)||Nicolas van Saberhagen|
|White paper||CryptoNote v 2.0|
|Initial release||18 April 2014|
|Latest release||0.12.0.0 / 24 March 2018|
|Operating system||Windows, Linux, macOS, BSD|
|Source model||BSD 3-Clause|
|Issuance||Decentralized, block reward|
|Block time||2 minutes (previously 1 minute)|
|Circulating supply||15,962,350 XMR (as of 24 April 2018[update])|
|Exchange rate||$137 (as of 9 July 2018[update])|
|Market cap||US$2.2 billion (as of 9 July 2018[update])|
The focus on privacy has attracted illicit use by people interested in evading law enforcement. The egalitarian mining process made it viable to distribute the mining effort opening new funding avenues for both legitimate online publishers and malicious hackers who covertly embed mining code into websites and apps.
Unlike many cryptocurrencies that are derivatives of Bitcoin, Monero is based on the CryptoNight proof-of-work hash algorithm, which comes from the CryptoNote protocol. It possesses significant algorithmic differences relating to blockchain obfuscation. By providing a high level of privacy, Monero is fungible, meaning that every unit of the currency can be substituted by another unit. This makes Monero different from public-ledger cryptocurrencies like Bitcoin, where addresses with coins previously associated with undesired activity can be blacklisted and have their coins refused by other users.
In particular, the ring signatures mix the spender's input with a group of others, making it exponentially more difficult to establish a link between each subsequent transaction. Also, the "stealth addresses" generated for each transaction make it impossible to discover the actual destination address of a transaction by anyone else other than the sender and the receiver. Finally, the "ring confidential transactions" mechanism hides the transferred amount.
Monero is designed to be resistant to application-specific integrated circuit mining, which is commonly used to mine other cryptocurrencies such as Bitcoin. It can be mined somewhat efficiently on consumer grade hardware such as x86, x86-64, ARM and GPUs.
Monero was originally launched by a Bitcointalk forum user only known as "thankful_for_today" under the name BitMonero which is a compound of Bit (as in Bitcoin) and Monero (literally meaning "coin" in Esperanto). Five days later, the currency's supporters opted for the name to be shortened to Monero.
In September 2014, Monero was attacked when an unknown party exploited a flaw in CryptoNote that permitted the creation of two subchains that refused to recognize the validity of transactions on each other. CryptoNote later released a patch for the flaw, which Monero implemented.
Monero experienced rapid growth in market capitalization and transaction volume during the year 2016, partly due to adoption in 2016 by major darknet market AlphaBay, which was closed in July 2017 by law enforcement.
On January 10, 2017, the privacy of Monero transactions were further strengthened by the adoption of Bitcoin Core developer Gregory Maxwell's algorithm Confidential Transactions, hiding the amounts being transacted, in combination with an improved version of Ring Signatures.
In April 2017 research highlighted three major threats to Monero users' privacy. The first relies on leveraging the ring signature size of zero, and ability to see the output amounts. The second, described as "Leveraging Output Merging", involves tracking transactions where two outputs belong to the same user, such as when a user is sending the funds to himself ("churning"). Finally the third threat, "Temporal Analysis", shows that predicting the right output in a ring signature is easier than previously thought.
Monero development team addressed the first concern in early 2017 with introduction of Ring Confidential Transactions (ringCT) as well as mandating a minimum size of ring signatures in the March 2016 protocol upgrade. Monero developers also noted that Monero Research Labs, their academic and research arm, already noted and outlined the deficiency in two public research papers in 2014 and 2015.
A user needs client software, a so-called wallet, to interact with the Monero network. The reference implementation developed by the Monero Project runs on Windows, MacOS, and Linux; several third party Monero wallets exist for Android and iOS, such as Monerujo and Cakewallet. Finally, a web wallet allows users to interact with the network entirely through the browser using a third party website.
The feasibility of CPU mining Monero has made it viable for malicious actors to covertly distribute miners embedded in malware, using the victim's hardware and electricity for the financial gain of the malware developer as well as legitimate uses with user consent.
Monero is sometimes employed by Bitcoin users to break link between transactions, with bitcoins first converted to Monero, then after some delay, converted back and sent to an address unrelated to those used before. Researchers have reported that the operators behind the global ransomware incident WannaCry have converted their proceeds into Monero. It is also the payment method of choice for The Shadow Brokers. Exchanges ShapeShift and Changelly are cooperating with police after it emerged that the WannaCry attackers used it to convert Bitcoin to Monero. "Any transactions made through ShapeShift can not be hidden or obscured and are thus 100 percent transparent" stated ShapeShift.
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