Cryptocurrencies use cryptographic protocols, or extremely complex code systems that encrypt sensitive data transfers, to secure their units of exchange. Cryptocurrency developers build these protocols on advanced mathematics and computer engineering principles that render them virtually impossible to break, and thus to duplicate or counterfeit the protected currencies. These protocols also mask the identities of cryptocurrency users, making transactions and fund flows difficult to attribute to specific individuals or groups.
The first decentralized cryptocurrency, bitcoin, was created in 2009 by pseudonymous developer Satoshi Nakamoto. It used SHA-256, a cryptographic hash function, as its proof-of-work scheme.... It was the first successful cryptocurrency to use scrypt as its hash function instead of SHA-256.
Cryptocurrency existed as a theoretical construct long before the first digital alternative currencies debuted. Early cryptocurrency proponents shared the goal of applying cutting-edge mathematical and computer science principles to solve what they perceived as practical and political shortcomings of "traditional" fiat currencies.