Hello everyone, I’m Chris.

I'm excited to share my journey and introduce my current research project, which has been made possible through the support of the PBS Foundation. As someone deeply passionate about scaling Ethereum, I’m thrilled to be contributing to the field, particularly in the area of Layer 2 protocols.

Background and Inspiration: Full Circle

My journey in blockchain began in 2016, just before the Ethereum DAO hack. I’d already had a long-standing interest in distributed and decentralized systems, but the DAO hack pulled me in, showcasing how resilient and adaptive blockchain communities could be. The community's coordinated response to recover from the hack, hard fork, and ultimately improve Ethereum was inspiring. This event solidified my belief in Ethereum's potential to scale and achieve mass adoption.

Back then, Ethereum faced major bottlenecks, primarily limited transaction throughput and poor user experience (UX). I started lurking in Ethereum research forums and, in 2018, applied for a grant from the Ethereum Foundation. To my amazement, the foundation funded my project, which aimed to onboard new developers into the space. On the scaling front, I interviewed many client developer teams, including engineers from Trinity and Prysm, about Ethereum’s roadmap and the sharding specification design. I also engaged with early Layer 2 efforts, such as Starknet and Plasma, and discussed mass adoption strategies with engineers from ENS and Status. I aggregated all this on my “Scaling Today” project.

This was just the beginning of my journey, and today, my interest in scaling Ethereum has only deepened.

Fast Forward to Today

I’m now a Blockchain R&D Engineer at Blockdaemon, where I’ve been immersed in the challenges and opportunities affecting various protocols and ecosystems, especially in the areas of MEV (Maximal Extractable Value), interoperability, and Layer 2 scaling solutions. While we have made progress towards scaling and mass adoption, many of the original challenges facing Ethereum remain. Thus my focus on Layer 2 protocols and their potential to drive mass adoption is a continuation of my early passion. As Vitalik Buterin recently pointed out:

"Layer 2s" and "sharding" often get described in public discourse as being two opposite strategies for how to scale a blockchain. But when you look at the underlying technology, there is a puzzle: the actual underlying approaches to scaling are exactly the same. You have some kind of data sharding. You have fraud provers or ZK-SNARK provers. You have solutions for cross-{rollup, shard} communication. The main difference is: who is responsible for building and updating those pieces, and how much autonomy do they have?

This insight captures Ethereum's shift from a pure L1 scaling model to a rollup-centric one. A major milestone in this evolution was The Merge, officially known as the Ethereum Paris Network Upgrade.

The Merge and the Road to Proposer-Builder Separation (PBS)

The Merge, executed in September 2022, marked Ethereum's transition from Proof-of-Work (PoW) to Proof-of-Stake (PoS), ending energy-intensive mining and paving the way for a more sustainable and secure Ethereum. This upgrade wasn't just about energy efficiency; it was a foundational step toward realizing Ethereum’s long-term vision of scalability and decentralization. By transitioning consensus mechanisms, Ethereum set the stage for future developments that aim to make the network faster and more secure while maintaining its core principles of decentralization.

However, scalability challenges persisted. While PoS improved energy efficiency, Layer 1 was still limited in terms of transaction throughput. This led to a shift towards rollups and Layer 2 solutions as key to Ethereum’s scaling roadmap, focusing on offloading transaction execution to Layer 2s while using the base layer for security and data availability.

This transition brought about the need for optimizing how blocks are proposed and built in a decentralized yet efficient manner. Enter Proposer-Builder Separation (PBS)—a solution that aims to address the growing influence of MEV on block production.

What is Proposer-Builder Separation?

Proposer-Builder Separation is a concept that divides responsibilities within the block-building process with the aim of reducing centralization risks and combating the exploitation of MEV. MEV, which refers to the additional value extractable by reordering, inserting, or censoring transactions within a block, and includes arbitrage and latency games, has grown significantly with the rise of DeFi and NFTs. Without proper mitigation, MEV could centralize power in the hands of a few, undermining the decentralization ethos of Ethereum.

PBS helps by separating the roles of block proposers and block builders. Proposers are responsible for selecting the final block from a set of pre-built blocks provided by builders, who specialize in efficiently constructing blocks. By decentralizing this process, Ethereum can better distribute the rewards of MEV, preventing a few entities from monopolizing the space. However, with these new solutions new problems also arise, such as the advent of the centralization of block building and trusted relayers.

My Research: Optimizing PBS in Ethereum Layer 2s

With the PBS Foundation’s support, I’m currently researching how to optimize proposer-builder separation specifically within Ethereum’s Layer 2 ecosystems. The foundation’s RFP for “Analysis of how PBS is being approached across L2s” describes the problem-space:

As the ecosystem of Layer 2 (L2s) networks matures, many L2s are starting to think about how they decentralize their sequencers (and provers for zkEVMs).  Among the numerous L2s that exist, it is likely that there will emerge a variety of different approaches to doing this, and as more and more transaction volume migrates from the base layer to L2s, this will become a space that centralization and censorship concerns will shift to. How then do we avoid the emergence of negative externalities for end-users of Ethereum on L2s?

We are interested in research that helps the ecosystem to understand if and how PBS might be implemented across L2s and what externalities this may cause.  How is PBS implemented within bounded and permissioned validator sets? How are inclusion lists implemented? What are the effects on centralization and censorship from the adoption of shared sequencers? Do any decentralized sequencer topologies allow for implementation of distributed block building or partial block auctions?

My project, titled "Optimizing for PBS in Ethereum L2s: Addressing Centralization and MEV Challenges," focuses on developing a comprehensive rubric to assess Layer 2 PBS strategies. This rubric evaluates key aspects such as:

• Leader selection in sequencing

• Token delegation and distribution

• Fair block-building processes

By analyzing these factors, the rubric aims to help Layer 2 developers and the broader blockchain community enhance fairness, efficiency, and decentralization in PBS approaches, particularly in relation to equitable MEV distribution.

This project has been both challenging and rewarding, and I’m particularly grateful to Simon Brown from the PBS Foundation for his mentorship. His insights have been invaluable in shaping the direction of my research.

Looking Forward

The Ethereum ecosystem is evolving rapidly, and the need for scalable, decentralized solutions is more critical than ever. My research is just one piece of the puzzle, but I hope it will contribute to making Ethereum more robust and accessible.

I want to emphasize the importance of the PBS Foundation’s work. Their dedication to decentralization and their support for independent research are invaluable to the Ethereum ecosystem, and I’m honored to be part of their efforts. I encourage anyone interested in blockchain to explore the opportunities provided by the PBS Foundation. In addition to the PBS Foundation, I would also like to extend my gratitude to Blockdaemon. Their encouragement and resources have enabled me to pursue this research and explore bleeding-edge solutions in scaling Ethereum.

Thank you for taking the time to learn about my project and the work of the PBS Foundation. I look forward to sharing more updates as my research progresses.