This paper reviews some recent developments in digital currency, focusing on platform-sponsored currencies such as Facebook Credits. In a model of platform management, we find that it will not likely be profitable for such currencies to expand to become fully convertible competitors to...

Since its launch in 2009 much has been written about Bitcoin, cryptocurrencies and blockchains. While the discussions initially took place mostly on blogs and other popular media, we now are witnessing the emergence of a growing body of rigorous academic research on these topics. By the nature...

Permissionless blockchains were constructed with a view to being sustainably secure. At the heart of blockchain consensus mechanisms was an explicit cost (whether it be work or stake) for participation in the network and the opportunity to propose blocks that would be added to the blockchain. A...