The advent of Bitcoin sparked the development of decentralized applications that rely on public ledgers (e.g. a blockchain) to enable a number of innovative IT solutions. However, traditional cryptocurrencies and smart contract [S96] systems (the main building blocks of such applications) offer no privacy guarantees, meaning all data is publicly available to third parties. Given surveillance concerns and new regulations such as the GDPR, this lack of privacy is an important issue that precludes a number of applications from being built on this technology. Besides that, these systems lack any accountability guarantees, meaning it is virtually impossible to reliably detect malfeasance.
In this project, we will establish frameworks for formally defining the security guarantees of complex protocols based on blockchains in such a way that proposed constructions can be proven to be achieve such properties. In particular, we will investigate definitions of smart contract systems with privacy and accountability guarantees as well as their compatibility with correlated building blocks such as cryptocurrencies and blockchain consensus protocols. Based on our frameworks, we will construct protocols that achieve such privacy and accountability guarantees based on techniques from the fields of blockchain consensus and secure multiparty computation. We believe these results will both give exciting theoretical insights and pave the way for reliable decentralized financial applications.
