Computer Science Thesis Proposal

— 4:30pm

In Person - Reddy Conference Room, Gates Hillman 4405

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

Blockchain-based Cryptography in the Real World

A recent line of work utilizes blockchains to achieve primitives that are known to be impossible to achieve under standard assumptions [CGJ+17, LJKW18, GG17]. In this thesis, we both address the limitations of such blockchain-based cryptography and expand this line of work by proposing new applications. Specifically, we show how to store secrets on a blockchain and how to use this primitive instead of the frequently used extractable witness encryption, which has been shown to be unlikely to exist in the standard model [GGHW14]. Next, we discuss how to use this primitive to achieve secure multi-party computation (MPC) which does not require parties to be online at the same time and requires no interaction between the participants. Further, we design a secure non-interactive system to support secure allegations.

As our next step, we wish to explore blockchain-based cryptography which is resilient to more powerful attackers. For this, we construct a blockchain-based fair exchange protocol, which we show to be secure in the presence of user-miner collusion. Finally, we propose to improve the state-of-the-art in the recently introduced You Only Speak Once (YOSO) model [GHK+21], which is tailored to the paradigm of serverless computing, blockchains being one of the most prominent examples of such a paradigm. The YOSO model is especially appealing to us as it allows to provide protocols that are secure against a powerful adaptive adversary which is able to corrupt parties at any time. 

Thesis Committee:

Vipul Goyal (Co-Chair, CMU / NTT Research)
Bryan Parno (Co-Chair)
Elaine Shi
Antigoni Polychroniadou (J.P. Morgan AI Research)
Tal Rabin (University of Pennsylvania / Amazon Web Services)

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