Zerocoin was a privacy protocol for Bitcoin developed at Johns Hopkins University by Matthew Green, Christina Garman, Ian Miers, and Aviel Rubin (IEEE S&P 2013). It was succeeded by the Zerocash protocol (2014), which the Electric Coin Co. implemented as the Zcash cryptocurrency launched in October 2016. The Zerocoin Project itself has been inactive since; its historical website zerocoin.org is no longer under the project's control and currently hosts unrelated gambling spam, so it must not be treated as an authoritative source.
