Crypto Seminar

— 5:30pm

In Person and Virtual - ET - Blelloch-Skees Conference Room and Zoom

ELISAWETA MASSEROVA , Ph.D. Student, Computer Science Department, Carnegie Mellon University

Storing and Retrieving Secrets on a Blockchain

Multiple protocols implementing exciting blockchain-based cryptographic functionalities (e.g., time-lock encryption, one-time programs, and fair multi-party computation) assume the existence of a cryptographic primitive called extractable witness encryption. Unfortunately, there are no known efficient constructions (or even constructions based on any well-studied assumptions) of extractable witness encryption.

In this work, we propose a protocol that uses a blockchain to provide a functionality that is effectively the same as extractable witness encryption. Hence, by making small adjustments to existing blockchains, we can easily implement applications that rely on extractable witness encryption. This includes both new applications, and those that previously existed only as theoretical designs. As a key building block, our protocol uses a new and highly efficient batched dynamic proactive secret sharing (DPSS) scheme which may be of independent interest. 

In Person and Zoom Participation. See announcement.  

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