Mastercoin is a digital currency and communications protocol built on the Bitcoin block chain. It is one of several prominent efforts to enable complex financial functions in a cryptocurrency. Planned features include the development of a decentralized exchange and the implementation of smart property and savings wallets. J. R. Willett published the first draft of the Mastercoin protocol in January 2012 as a white paper, in which he proposed that existing Bitcoin protocol “can be used as a protocol layer, on top of which new currency layers with new rules can be built without changing the foundation.”