A brief overview of the much-talked-about digital currency:
BITCOIN, the world’s “first decentralised digital currency”, was launched in 2009 by a mysterious person (or persons) known only by the pseudonym Satoshi Nakamoto. It has been in the news this week as the value of an individual Bitcoin, which was just $20 at the beginning of February, hit record highs above $250, before falling abruptly to below $150 on April 11th. What exactly is Bitcoin, and how does it work?
Unlike traditional currencies, which are issued by central banks, Bitcoin has no central monetary authority. Instead it is underpinned by a peer-to-peer computer network made up of its users’ machines, akin to the networks that underpin BitTorrent, a file-sharing system, and Skype, an audio, video and chat service. Bitcoins are mathematically generated as the computers in this network execute difficult number-crunching tasks, a procedure known as Bitcoin “mining”. The mathematics of the Bitcoin system were set up so that it becomes progressively more difficult to “mine” Bitcoins over time, and the total number that can ever be mined is limited to around 21m. There is therefore no way for a central bank to issue a flood of new Bitcoins and devalue those already in circulation.
And a bit more technical detail:
All transactions are secured using public-key encryption, a technique which underpins many online dealings. It works by generating two mathematically related keys in such a way that the encrypting key cannot be used to decrypt a message and vice versa. One of these, the private key, is retained by a single individual. The other key is made public. In the case of Bitcoin transactions, the intended recipient’s public key is used to encode payments, which can then only be retrieved with the help of the associated private key. The payer, meanwhile, uses his own private key to approve any transfers to a recipient’s account.
This provides a degree of security against theft. But it does not prevent an owner of Bitcoins from spending his Bitcoins twice—the virtual analogue of counterfeiting. In a centralised system, this is done by clearing all transactions through a single database. A transaction in which the same user tries to spend the same money a second time (without having first got it back through another transaction) can then be rejected as invalid.
The whole premise of Bitcoin is to do away with a centralised system. But tracking transactions in a sprawling, dispersed network is tricky. Indeed, many software developers long thought it was impossible. It is the problem that plagued earlier attempts to establish virtual currencies; the only way to prevent double spending was to create a central authority. And if that is needed, people might as well stick with the government devil they know.
To get around this problem, Bitcoins do not resemble banknotes with unique serial numbers. There are no virtual banknote files with an immutable digital identity flitting around the system. Instead, there is a list of all transactions approved to date. These transactions come in two varieties. In some, currency is created; in others, nominal amounts of currency are transferred between parties.
