Ethereum After The Merge: Is It Still Secure?

Joachim is a PhD student at Stanford working with David Tse on Internet-scale open-participation consensus (in more hype terms: the technical foundations of blockchains). His current research focus is provable consensus security for next-generation Ethereum, and provable security and performance of proof-of-stake consensus under bandwidth constraints and network-level attacks. In an earlier life, he published in information and coding theory. He has been supported by Protocol Labs PhD Fellowship and Ethereum Foundation.

The transition of Ethereum, the second largest cryptocurrency, from proof-of-work to proof-of-stake is a major feat of engineering. Yet, regrettably from a blockchain science point of view, Ethereum went from a protocol with a security proof to one without. Furthermore, the current protocol is complex, and has already been through multiple cycles of attacks and patches (on the protocol itself, not “only” on the implementation). Why is this so? Ethereum aims to satisfy an ambitious list of desiderata, some of which have never been achieved simultaneously before. We present two examples with recent progress: First, our ebb-and-flow protocols and accountability gadgets offer a way to reconcile accountable safety and liveness in an environment with dynamic participation. Second, we propose Goldfish, a simple and provably secure drop-in replacement for Ethereum’s current fork-choice rule, that achieves resilience to chain reorganizations under dynamic participation.