Blockchains with Private Computation
The blockchain technology in essence implements a decentralizedpublic ledger: onewhich cannot be altered, is append only, and, is visible to everyone. Numerous impor-tant applications of this technique have been transforming the world of cybersecurityand cryptography over the last several years. In this project, we propose to undertakean ambitious effort to build what we call asmart private ledger. Different parts ofthe smart ledger would have different visibility criteria: some would be visible onlyto certain parties, some only to parties having certain credentials, some only availableafter a specific date or time, and some only when a particular event happens in thereal world (such as a court order). Indeed, some parts could be completely public asbefore. Thus, we propose to go from a passive public ledger to a smart active ledger.We also propose to enable usefulcomputations on the privately stored data.The ability to handle secret access controlled data could be a game changer forthe blockchain technology. It enables a number of new applications. The most basicapplication would be a secure decentralized data storage system with access control.The policy regarding who could access the stored data (and when) would be surprisinggeneral. Enabling computation over the stored private data opens a number of newavenues. This would allow us to buildprivate smart contractswhere code of the smartcontract as well as its input and intermediate data will be hidden. We anticipate appli-cations inprivacy-preserving data mining, and, in building a full-fledged decentralizedcloud capable of storing as well as computing on private data.
