PoS Blockchains - Designs, Consensus, Attacks

web3 with a16z crypto

with @lera_banda @tim_roughgarden @smc90

We share an overview of proof-of-stake (PoS) blockchains -- from quick background on how blockchains work, differences between PoS & PoW (including the energy question), and approaches to improving both; to digging deeper into Sybill attacks and Sybill resistance... and much more on the design (and some debates) of PoS blockchains overall.
We therefore also go into different consensus approaches for PoS blockchains, from Nakamoto to BFT-style consensus and beyond; touch briefly on the question/ debate of centralization vs. decentralization in practice when it comes to PoS blockchains; and cover costless simulation and long-range attacks... plus briefly discuss topics like slashing and more, when issues are "escalated" to the social vs. protocol layer. [We don’t go into too much detail on Ethereum or the Merge i this episode, since we cover that in an upcoming episode.]

Our expert guests in this episode (in conversation with host Sonal Chokshi) are:

• Valeria (Lera) Nikolaenko, a16z crypto research partner -- who was previously on Novi at Meta (formerly Facebook), where she was a research scientist and cryptographer for the Diem blockchain; Lera specializes in modern cryptography, post-quantum cryptography, proof-of-stake blockchain design, and more.
• Tim Roughgarden, a16z crypto Head of Research -- who, among many other things, is also a computer science professor at Columbia, and before that Stanford (and who joins as co-host in this episode).

Be sure to also subscribe to our YouTube channel for several introductory and deep-dive videos -- including the exact topics discussed in this episode, on an overview of PoS Blockchains & on long-range attacks on PoS blockchains, as presented by Lera -- just search for 'a16z crypto research'. See also Tim Roughgarden's YouTube channel with several lectures on foundations of blockchains, including on topics mentioned in this episode (Tendermint protocol, longest-range consensus, random leader selection, more).
Finally, if you’d also like a more high-level survey of research in web3 -- and a quick tour through tech topics like VDFs, rollups, and more -- be sure to check out episode 8 in this feed, which was also a hallway-style jam with the research team...
As a reminder, none of the following investment, business, legal, or tax advice; please see a16z.com/disclosures for more important information, including a link to a list of our investments.