GHash.io

GHash.io was founded and owned by CEX.io, a cryptocurrency exchange that continues to operate today. Apart from mining bitcoin, GHash.io hosted a multipool for mining altcoins, as well as separate pools for mining Litecoin, Dogecoin, Auroracoin, and Darkcoin. Altcoin mining options were available for independent miners, while bitcoin mining could also be done in the cloud by purchasing cloud-based mining power on CEX.io.{{Citation needed|date=August 2022}}

Traders on CEX.io could buy shares of GHash.io mining hardware to operate on the GHash.io mining pool. After GHash.io closed in 2016, CEX.io continued operating as a bitcoin exchange.{{Citation needed|date=August 2022}}

The possibility of a 51% attack was feared due to the popularity of GHash.io's mining pool. This kind of attack occurs when a single miner or mining pool is able to mine multiple bitcoin block rewards in a row. This would be a problem for the bitcoin network, because it hypothetically allows the mining pool to double-spend (counterfeit) bitcoins.{{cite web|author=Michael J. Casey and Paul Vigna|title=BitBeat: Mining Pool Rejects Short-Term Fixes To Avert "51% Attack"|publisher=WSJ Blogs|date=16 June 2014|url=https://blogs.wsj.com/moneybeat/2014/06/16/bitbeat-a-51-attack-what-is-it-and-could-it-happen/}} In July 2014, the GHash.io mining pool briefly exceeded the 51% threshold, which forced the bitcoin community to discuss the possibility of finding a common solution to this threat.{{cite news|author=L.S.|title=How bitcoin mining works |newspaper=The Economist |date=20 January 2015 |url=https://www.economist.com/the-economist-explains/2015/01/20/how-bitcoin-mining-works}}{{cite web|author=Alex Hern|title=Bitcoin currency could have been destroyed by '51%' attack|work=The Guardian|date=16 June 2014|url=https://www.theguardian.com/technology/2014/jun/16/bitcoin-currency-destroyed-51-attack-ghash-io}} The pool developing the majority caused a prominent bitcoin developer Peter Todd to sell half of his holdings.{{cite web|author=David Canellis|title=One mining pool controls a dangerously dominant share of BitcoinSV's hash rate|publisher=The Next Web|date=26 April 2019|url=https://thenextweb.com/hardfork/2019/04/26/calvin-ayre-coingeek-bitcoin-sv-hash-rate-51-percent-double-spend}} The news reportedly caused bitcoin's price to drop from $633 to $600 at the time.{{cite web|author=Tim Hornyak|title=One group controls 51 percent of Bitcoin mining, threatening security sanctity|publisher=IDG PC World|date=16 June 2014|url=https://www.pcworld.com/article/2364000/bitcoin-price-dips-as-backers-fear-mining-monopoly.html}}

Since no long-term solution to the 51% problem is known, the participants agreed to implement some temporary measures. GHash.io released a voluntary statement promising that it would not exceed 40% of the overall bitcoin hashrate.{{cite web|author=Kevin Kelleher|title=The gold rush days of bitcoin mining are over, and not because of the price|publisher=Quartz|date=23 December 2014|url=https://qz.com/316898/the-gold-rush-days-of-bitcoin-mining-are-over-and-not-because-of-the-price/}} Moreover, GHash.io representatives asked other mining pools to follow their example for the sake of the entire bitcoin community.{{cite web|author=Alex Wilhelm|title=Popular Bitcoin Mining Pool Promises To Restrict Its Compute Power To Prevent Feared '51%' Fiasco|publisher=Techcrunch|date=16 July 2014|url=https://techcrunch.com/2014/07/16/popular-bitcoin-mining-pool-promises-to-restrict-its-compute-power-to-prevent-feared-51-fiasco/}} It also stated that a new committee should be created to act as a watchdog against the 51% problem. This committee would include representatives of the mining pools, bitcoin businesses and other specialists in the field.

The 51% discussion received broad coverage in the media, beyond publications which commonly focus on cryptocurrency news ArsTechnica,{{cite web|url=https://arstechnica.com/business/2014/07/bitcoin-pool-ghash-io-commits-to-40-hashrate-limit-after-its-51-breach/|publisher=ArsTechnica|title=Bitcoin pool GHash.io commits to 40% hashrate limit after its 51% breach|date=2014-07-16|access-date=2014-10-14}} Bloomberg View,{{cite news|author=Bershidsky Leonid|title=Trust Will Kill Bitcoin|newspaper=Bloomberg.com|publisher=Bloomberg View|date=17 July 2014|url= http://www.bloombergview.com/articles/2014-07-17/trust-will-kill-bitcoin}} Vice Motherboard, International Business Times.{{cite web|author= Anthony Cuthbertson|title=Cryptocurrency News Round-Up: App Teaches Bitcoin to Children & GHash Commits to 40% Hashrate|work=International Business Times|date=17 July 2014|url=http://www.ibtimes.co.uk/cryptocurrency-news-round-app-teaches-bitcoin-children-ghash-commits-40-hashrate-1457056}}

In March 2015, GHash.io was struck by a crippling DDOS attack, possibly in response to the group breaching 51%.{{cite web |last1=Quentson |first1=Andrew |title=Bitcoin Mining Pool Ghash.io DDos-ed in Response to threat of 51% attack? |url=https://www.ccn.com/bitcoin-mining-pool-ghash-io-ddos-ed-response-51-attack/ |website=CCN |access-date=26 June 2023 |date=June 15, 2014}} By the end of 2015, GHash.io had stopped its mining activity in response to falling bitcoin prices.{{cite web |last1=Madore |title=Ghash / CEX Scaling Back Mining Pool |url=https://www.ccn.com/ghash-cex-scaling-back-mining-pool |website=CCN |access-date=26 June 2023}}{{cite web|author=Rob Price|title=The 21 companies that control bitcoin

|publisher=Business Insider|date=13 August 2015|url=https://www.businessinsider.com/bitcoin-pools-miners-ranked-2015-7}}

{{reflist}}

• [https://web.archive.org/web/20180112182929/http://ghash.io/ Official website]

{{Bitcoin}}

{{Portalbar|Internet|Economics|Free and open-source software}}

{{Authority control}}

Category:Cryptocurrencies

Category:Financial services companies established in 2013

Category:Bitcoin companies