What is Bitcoin? Bitcoin is an open source, peer-to-peer payment network and digital currency introduced in 2009 by pseudonymous developer "Satoshi Nakamoto". Bitcoin has been called a cryptocurrency because it uses public-key cryptography for security. Users send payments by broadcasting digitally signed messages that transfer ownership of bitcoins, the unit of currency. A decentralized network of specialized computers verifies and timestamps all transactions using a proof-of-work system. The operators of these computers, known as "miners", are rewarded with transaction fees and newly minted bitcoins. Bitcoin has been a subject of scrutiny for its use in illicit activities. In 2013 the FBI shut down the Silk Road online black market and seized US$28.5 million worth of bitcoin from the alleged mastermind. Theft of bitcoins has been covered extensively in the media. The risk of theft can be mitigated by generating and storing keys offline. It is no...