In 1998, Wei Dai published a description of “b-money”, characterized as an anonymous, distributed electronic cash system. Shortly thereafter, Nick Szabo described bit gold. The first decentralized cryptocurrency, bitcoin, was created in 2009 by pseudonymous developer Satoshi Nakamoto. On 6 August 2014, the UK announced its Treasury had been commissioned to do a study of cryptocurrencies, and what role, if any, they can play in the UK economy.
The study was also to report on whether regulation should be considered. The system does not require a central authority, its state is maintained through distributed consensus. The system keeps an overview of cryptocurrency units and their ownership. The system defines whether new cryptocurrency units can be created. If new cryptocurrency units can be created, the system defines the circumstances of their origin and how to determine the ownership of these new units. Ownership of cryptocurrency units can be proved exclusively cryptographically. The system allows transactions to be performed in which ownership of the cryptographic units is changed.
A transaction statement can only be issued by an entity proving the current ownership of these units. If two different instructions for changing the ownership of the same cryptographic units are simultaneously entered, the system performs at most one of them. In March 2018, the word cryptocurrency was added to the Merriam-Webster Dictionary. The term altcoin has various similar definitions. Stephanie Yang of The Wall Street Journal defined altcoins as “alternative digital currencies,” while Paul Vigna, also of The Wall Street Journal, described altcoins as alternative versions of bitcoin. A blockchain account can provide functions other than making payments, for example in decentralized applications or smart contracts.
Decentralized cryptocurrency is produced by the entire cryptocurrency system collectively, at a rate which is defined when the system is created and which is publicly known. As of May 2018, over 1,800 cryptocurrency specifications existed. Most cryptocurrencies are designed to gradually decrease production of that currency, placing a cap on the total amount of that currency that will ever be in circulation. The validity of each cryptocurrency’s coins is provided by a blockchain. A blockchain is a continuously growing list of records, called blocks, which are linked and secured using cryptography. Blockchains are secure by design and are an example of a distributed computing system with high Byzantine fault tolerance.
Decentralized consensus has therefore been achieved with a blockchain. Cryptocurrencies use various timestamping schemes to “prove” the validity of transactions added to the blockchain ledger without the need for a trusted third party. The first timestamping scheme invented was the proof-of-work scheme. The most widely used proof-of-work schemes are based on SHA-256 and scrypt. The proof-of-stake is a method of securing a cryptocurrency network and achieving distributed consensus through requesting users to show ownership of a certain amount of currency. It is different from proof-of-work systems that run difficult hashing algorithms to validate electronic transactions.