“Unlike the communities traditionally associated with the word “anarchy”, in a crypto-anarchy the government is not temporarily destroyed but permanently forbidden and permanently unnecessary. It's a community where the threat of violence is impotent because violence is impossible, and violence is impossible because its participants cannot be linked to their true names or physical locations.” -Wei Dai
A cryptocurrency is a medium of exchange using cryptography to secure the transactions and to control the creation of new units. Cryptocurrencies are a subset of alternative currencies, or specifically of digital currencies. Bitcoin became the first decentralized cryptocurrency in 2009. Since then, hundreds of cryptocurrencies have been created they are referred as Altcoins.
Cryptocurrency is produced by the entire cryptocurrency system collectively, at a rate which is defined when the system is created and publicly known. In centralized banking and economic systems such as the Federal Reserve System, corporate boards or governments control the supply of currency by printing units of fiat money or demanding additions to digital banking ledgers. However, companies or governments cannot produce units of cryptocurrency and as such, have not so far provided backing for other firms, banks or corporate entities which hold asset value measured in a decentralized cryptocurrency.
Put another way, cryptocurrency is electricity converted into lines of code with monetary value. In the simplest of forms, cryptocurrency is digital currency.
Bitcoin is a decentralized digital currency that enables instant payments to anyone, anywhere in the world. Bitcoin uses peer-to-peer technology to operate with no central authority: transaction management and money issuance are carried out collectively by the network.
The original Bitcoin software by Satoshi Nakamoto was released under the MIT license. Most client software, derived or “from scratch”, also use open source licensing.
Bitcoin is the first successful implementation of a distributed crypto-currency, described in part in 1998 by Wei Dai on the cypherpunks mailing list. Building upon the notion that money is any object, or any sort of record, accepted as payment for goods and services and repayment of debts in a given country or socio-economic context, Bitcoin is designed around the idea of using cryptography to control the creation and transfer of money, rather than relying on central authorities.
Prior to the release of bitcoin there were a number of precursor ecash technologies starting with the issuer based ecash protocols of David Chaum and Stefan Brands, and moving on to distributed digital scarcity based ecash protocols starting from Adam Back's hashcash, Wei Dai's b-money, Nick Szabo's bit-gold and Hal Finney's RPOW which build on hashcash.
Independently and at around the same time Wei Dai proposed b-money and Nick Szabo proposed bit-gold. Subsequently Hal Finney implemented and deployed RPOW a reusable form of hashcash based on IBM secure TPM hardware and remote attestation (centralized but with no issuer inflation risk).
Since the initial bit-gold proposal which proposed a collectible market based mechanism for inflation control Nick Szabo also investigated some additional enabling aspects for decentralized asset registers including Byzantine network issues.
There has been much speculation as to the identity of Satoshi Nakamoto with suspects including Wei Dai, Hal Finney and accompanying denials. The possibility that Satoshi Nakamoto was a computer collective in the European financial sector has also been bruited.
In November 2008, a paper was posted on the internet under the name Satoshi Nakamoto titled Bitcoin: A Peer-to-Peer Electronic Cash System. This paper detailed methods of using a peer-to-peer network to generate what was described as “a system for electronic transactions without relying on trust”. In January 2009, the bitcoin network came into existence with the release of the first open source bitcoin client and the issuance of the first bitcoins, with Satoshi Nakamoto mining the first block of bitcoins ever (known as the “genesis block”), which had a reward of 50 bitcoins. The value of the first bitcoin transactions were negotiated by individuals on the bitcointalk forums with one notable transaction of 10,000 BTC used to indirectly purchase two pizzas delivered by Papa John’s.
On 6 August 2010, a major vulnerability in the bitcoin protocol was spotted. Transactions weren't properly verified before they were included in the transaction log or “block chain” which let users bypass bitcoin's economic restrictions and create an indefinite number of bitcoins. On 15 August, the vulnerability was exploited; over 184 billion bitcoins were generated in a transaction, and sent to two addresses on the network. Within hours, the transaction was spotted and erased from the transaction log after the bug was fixed and the network forked to an updated version of the bitcoin protocol. This was the only major security flaw found and exploited in Bitcoin's history.
Mining is the process of adding transaction records to Bitcoin's public ledger of past transactions. This ledger of past transactions is called the block chain as it is a chain of blocks. The block chain serves to confirm transactions to the rest of the network as having taken place. Bitcoin nodes use the block chain to distinguish legitimate Bitcoin transactions from attempts to re-spend coins that have already been spent elsewhere.
Mining is intentionally designed to be resource-intensive and difficult so that the number of blocks found each day by miners remains steady. Individual blocks must contain a proof of work to be considered valid. This proof of work is verified by other Bitcoin nodes each time they receive a block. Bitcoin uses the hashcash proof-of-work function.
The primary purpose of mining is to allow Bitcoin nodes to reach a secure, tamper-resistant consensus. Mining is also the mechanism used to introduce Bitcoins into the system: Miners are paid any transaction fees as well as a “subsidy” of newly created coins. This both serves the purpose of disseminating new coins in a decentralized manner as well as motivating people to provide security for the system.
Bitcoin mining is so called because it resembles the mining of other commodities: it requires exertion and it slowly makes new currency available at a rate that resembles the rate at which commodities like gold are mined from the ground.
Bitcoins are mined using a cryptographic algorithm called SHA-256. This algorithm is simple enough to be done with pencil and paper, as shown in this video. Not surprisingly, this is a thoroughly impractical way to mine. One round of the algorithm takes 16 minutes, 45 seconds which works out to a hash rate of 0.67 hashes per day.