Important January 2016 status update: Wei dai bitcoin miner has bitcoin failed? Bitcoin is an open source peer-to-peer electronic cash system developed by Satoshi Nakamoto.
Bitcoin relies on cryptographic principles to create unique, unreproducible, and divisible tokens of value. Users hold the cryptographic keys to their own money and transact directly with each other, with the help of the network to check for double-spending. In essence, that means that it’s managed collectively by a global network of users, so no bank or payment processor is required between buyers and sellers in any transaction. Users begin with Bitcoin by downloading its client program for Linux, Mac or Windows, thereby creating a digital wallet and associated Bitcoin address for themselves. The root problem with conventional currency is all the trust that’s required to make it work.
The central bank must be trusted not to debase the currency, but the history of fiat currencies is full of breaches of that trust. Banks must be trusted to hold our money and transfer it electronically, but they lend it out in waves of credit bubbles with barely a fraction in reserve. We have to trust them with our privacy, trust them not to let identity thieves drain our accounts. A generation ago, multi-user time-sharing computer systems had a similar problem. Before strong encryption, users had to rely on password protection to secure their files, placing trust in the system administrator to keep their information private. Privacy could always be overridden by the admin based on his judgment call weighing the principle of privacy against other concerns, or at the behest of his superiors.
It’s time we had the same thing for money. With e-currency based on cryptographic proof, without the need to trust a third party middleman, money can be secure and transactions effortless. One of the fundamental building blocks for such a system is digital signatures. A digital coin contains the public key of its owner. To transfer it, the owner signs the coin together with the public key of the next owner. Anyone can check the signatures to verify the chain of ownership.
It works well to secure ownership, but leaves one big problem unsolved: double-spending. Any owner could try to re-spend an already spent coin by signing it again to another owner. Bitcoin’s solution is to use a peer-to-peer network to check for double-spending. It takes advantage of the nature of information being easy to spread but hard to stifle. The result is a distributed system with no single point of failure.