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Ph.D. Defense: Saad Quader
October 23, 2020 @ 3:30 pm - 5:30 pm EDT
Title: Security of Proof-of-Stake Blockchains
Ph.D. Candidate: Saad Quader
Major Advisor: Prof. Alexander Russell
Associate Advisors: Prof. Benjamin Fuller and Prof. Walter Krawec
Date/Time: Friday, October 23rd, 2020, 3:30 pm – 5:30 pm
Meeting Number: 120 029 4507
Join by phone
+1-415-655-0002 US Toll
Access Code: 120 029 4507
In the past decade, blockchain technology has emerged as a foundation for a diverse range of distributed applications, notably cryptocurrencies and decentralized ledger. These protocols allow the users — across the globe and not needing to trust one another — exchange messages and eventually reach an agreement.
Currently, the most popular blockchain technology is the Proof-of-Work (PoW) paradigm, popularized by the cryptocurrency Bitcoin. Alternative paradigms, such as Proof-of-Stake (PoS), aim to provide the same functionalities and security as PoW while requiring only a fraction of a PoW network’s enormous energy cost. This, however, is non-trivial.
In this dissertation, we study the security of PoS blockchains in the eventual consensus model under the so-called “longest-chain rule.”
- First, we show that PoS blockchains have the same asymptotic security guarantee as those of the PoW blockchains (published at ACM SODA 2020).
- Next, we generalize this analysis and show that we can securely use a broader class of protocols for electing “leaders” — users who can create new blocks — at each round (accepted at IEEE ICDCS 2020).
- Finally, we analyze the security of the “randomness beacon” within two important PoS blockchain protocols: Ouroboros Praos and Snow White. Our results demarcate the parameter settings for which these protocols remain secure.
Our results have already made an impact in the industry, in that a leading PoS cryptocurrency Cardano is using our results and recommendations for designing their protocol.
About the Talk: In my talk, I will focus on our recent ICDCS 2020 paper. My goal will be to
- Tell you what “consistency” means for blockchains
- Motivate the question “how fast do we achieve consistency?”
- Tell you about the insights we gained from our work
- Give you intuitions behind our analysis