Zerocoin was conceived as cryptographic extension to Bitcoin that (if adopted) would bring true cryptographic anonymity to Bitcoin. It works at the protocol level and doesn't require new trusted parties or services, such as a bitcoin laundry. It was to replace the public transactions of Bitcoin with private transactions. Spending transactions would be made to appear as though they were from newly minted coins, because the serial number of the zerocoin would not appear in the blockchain. Subsequently, developer Matthew Green announced that Zerocoin would be independent of Bitcoin. Green did not believe that the Bitcoin community would integrate Zerocoin's protocol into Bitcoin because of fear of complete anonymity, additional mining costs, and a fear of new, untested features.
- Ian Miers, Christina Garman, Matthew Green, Aviel D. Rubin. "Zerocoin: Anonymous Distributed E-Cash from Bitcoin". Whitepaper. The Johns Hopkins University Department of Computer Science. http://spar.isi.jhu.edu/~mgreen/ZerocoinOakland.pdf. Retrieved 2014-04-02.
- Green, Matthew (April 11, 2013). "Zerocoin: making Bitcoin anonymous". blog. Blogger. http://blog.cryptographyengineering.com/2013/04/zerocoin-making-bitcoin-anonymous.html. Retrieved 2014-04-02.
- Greenberg, Andy (13 January 2014). "Bitcoin Anonymity Upgrade Zerocoin To Become An Independent Cryptocurrency". FORBES. http://www.forbes.com/sites/andygreenberg/2014/01/13/bitcoin-anonymity-upgrade-zerocoin-to-become-its-own-cryptocurrency/. Retrieved 2014-04-02.