Double-spending Contents Prevention References Navigation menuThe Double Spending Problem and Cryptocurrencies"Digital Cash"0802.0832v1cs.CR10.1.1.120.5210.1109/ICDCS.2007.91"The Mission to Decentralize the Internet""Why Proof-of-work isn't suitable for small cryptocurrencies"e

Digital currenciesFinancial cryptographyPayment systemsInternet fraudDistributed computingCryptocurrencies


digital cashcounterfeit moneyinflationcirculationblind signaturessecret splittingBitcoinforksBitcoin Goldonlinetrusted third partysingle point of failuredistributed systemscryptocurrencybitcoincryptographic protocolproof-of-work systemledgerblockchain




Double-spending is a potential flaw in a digital cash scheme in which the same single digital token can be spent more than once. Unlike physical cash, a digital token consists of a digital file that can be duplicated or falsified.[1][2] As with counterfeit money, such double-spending leads to inflation by creating a new amount of copied currency that did not previously exist. This devalues the currency relative to other monetary units or goods and diminishes user trust as well as the circulation and retention of the currency. Fundamental cryptographic techniques to prevent double-spending, while preserving anonymity in a transaction, are blind signatures and, particularly in offline systems, secret splitting.[2]


A double-spending attack is a potential attack against cryptocurrencies that has happened to several cryptocurrencies, e.g. due to the 51% attack. While it hasn't happened against many of the largest cryptocurrencies, such as Bitcoin (with even the capability arising for it in 2014), it has happened to one of its forks, Bitcoin Gold, then 26th largest cryptocurrency.




Contents





  • 1 Prevention

    • 1.1 Centralized


    • 1.2 Decentralized



  • 2 References




Prevention


The prevention of double-spending attack has taken two general forms: centralized and decentralized.



Centralized


This is usually implemented using an online central trusted third party that can verify whether a token has been spent.[2] This normally represents a single point of failure from both availability and trust viewpoints.



Decentralized


By 2007, a number of distributed systems for the prevention of double-spending had been proposed.[3][4]


The cryptocurrency bitcoin implemented a solution in early 2009. It uses a cryptographic protocol called a proof-of-work system to avoid the need for a trusted third party to validate transactions. Instead, transactions are recorded in a public ledger called a blockchain. A transaction is considered valid when it is included in the blockchain that contains the greatest amount of computational work. This makes double-spending more difficult as the size of the overall network grows.[5] Other cryptocurrencies also have similar features.


Decentralized currencies that rely on blockchain are vulnerable to the 51% attack, in which a malicious actor can rewrite the ledger if they control enough of the computational work being done.[6]



References




  1. ^ The Double Spending Problem and Cryptocurrencies. Banking & Insurance Journal. Social Science Research Network (SSRN). Accessed 24 December 2017.


  2. ^ abc Mark Ryan. "Digital Cash". School of Computer Science, University of Birmingham. Retrieved 2017-05-27..mw-parser-output cite.citationfont-style:inherit.mw-parser-output .citation qquotes:"""""""'""'".mw-parser-output .citation .cs1-lock-free abackground:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center.mw-parser-output .citation .cs1-lock-limited a,.mw-parser-output .citation .cs1-lock-registration abackground:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center.mw-parser-output .citation .cs1-lock-subscription abackground:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registrationcolor:#555.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration spanborder-bottom:1px dotted;cursor:help.mw-parser-output .cs1-ws-icon abackground:url("//upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Wikisource-logo.svg/12px-Wikisource-logo.svg.png")no-repeat;background-position:right .1em center.mw-parser-output code.cs1-codecolor:inherit;background:inherit;border:inherit;padding:inherit.mw-parser-output .cs1-hidden-errordisplay:none;font-size:100%.mw-parser-output .cs1-visible-errorfont-size:100%.mw-parser-output .cs1-maintdisplay:none;color:#33aa33;margin-left:0.3em.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-formatfont-size:95%.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-leftpadding-left:0.2em.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-rightpadding-right:0.2em


  3. ^ Jaap-Henk Hoepman (2008). "Distributed Double Spending Prevention". arXiv:0802.0832v1 [cs.CR].


  4. ^ Osipkov, I.; Vasserman, E. Y.; Hopper, N.; Kim, Y. (2007). "Combating Double-Spending Using Cooperative P2P Systems". 27th International Conference on Distributed Computing Systems (ICDCS '07). p. 41. CiteSeerX 10.1.1.120.52. doi:10.1109/ICDCS.2007.91.


  5. ^ Janus Kopfstein (12 December 2013). "The Mission to Decentralize the Internet". The New Yorker. Retrieved 30 December 2014. The network’s "nodes"—users running the bitcoin software on their computers—collectively check the integrity of other nodes to ensure that no one spends the same coins twice. All transactions are published on a shared public ledger, called the "block chain"


  6. ^ Varshney, Neer (2018-05-24). "Why Proof-of-work isn't suitable for small cryptocurrencies". Hard Fork | The Next Web. Retrieved 2018-05-25.









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