consumes large quantities of electricity and has been criticized for its environmental impact.[10]\ \ Before bitcoin, several digital cash technologies were released, starting with David Chaum's ecash in the 1980s.[11] The idea that solutions to computational puzzles could have some value was first proposed by cryptographers Cynthia Dwork and Moni Naor in 1992.[12][11] The concept was independently rediscovered by Adam Back who developed Hashcash, a proof-of-work scheme for spam control in 1997.[11] The first proposals for distributed digital scarcity-based cryptocurrencies came from cypherpunks Wei Dai (b-money) and Nick Szabo (bit gold) in 1998.[13] In 2004, Hal Finney developed the first currency based on reusable proof of work.[14] These various attempts were not successful:[11] Chaum's concept required centralized control and no banks wanted to sign on, Hashcash had no protection against double-spending, while b-money and bit gold were not resistant to Sybil attacks.[11]\ \ The domain name bitcoin.org was registered on 18 August 2008.[15] On 31 October 2008, a link to a white paper authored by Satoshi Nakamoto titled Bitcoin: A Peer-to-Peer Electronic Cash System was posted to a cryptography mailing list.[16] Nakamoto's identity remains unknown.[5] According to computer scientist Arvind Narayanan, all individual components of bitcoin originated in earlier academic literature.[11] Nakamoto's innovation was their complex interplay resulting in the first decentralized, Sybil resistant, Byzantine fault tolerant digital cash system, that would eventually be referred to as the first blockchain.[11][17] Nakamoto's paper was not peer reviewed and was initially ignored by academics, who argued that it could not work.[11]\ \ Nakamoto released bitcoin as open-source software.[18] On 3 January 2009, the bitcoin network was created when Nakamoto mined the starting block of the chain, known as the genesis block.[19] Embedded in this block was the text "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks", which is the date and headline of an issue of The Times newspaper.[6] Nine days later, Hal Finney received the first bitcoin transaction: ten bitcoins from Nakamoto.[20] Wei Dai and Nick Szabo were also early supporters.[19] On May 22, 2010, the first known commercial transaction using bitcoin occurred when programmer Laszlo Hanyecz bought two Papa John's pizzas for 10,000, in what would later be celebrated as "Bitcoin Pizza Day".[21]\ \