The first programmable blockchain, Ethereum, is evolving into a secure, environment-friendly and sustainable ecosystem through a series of upgrades. The most recent upgrade in town was the Merge, which switched the consensus mechanism from proof of work to proof of stake. Vitalik Buterin has published the latest upgrade plans and here I am with the quick recaps if you have missed then. Here we go………

Unlike previous upgrade plans, the various upgrades are under progress in parallel.

The Merge

The transition to proof of stake was completed once the mainnet merged with the beacon chain on September 15, 2022. Upcoming updates include allowing validators to withdraw their stake, finalizing blocks within a slot (Single slot finality), secret leader election (to select the block proposer randomly) and cryptographic signature schemes which are quantum-safe aggregation-friendly.

The Surge

This phase includes a set of updates, primarily improving the transaction throughput. The initial plan was to implement sharding, allowing parallel processing of transactions by 64 shards. But, as layer two technologies evolved, the sharding plan was updated to a format that improves the scalability of rollups. The proposed Proto-Danksharding (PDS) aims to move all computation to L2 (execution layer) and data to be posted on the Ethereum mainnet (data layer). It introduces a new Ethereum transaction type called a Blob-carrying transaction which can carry an extra piece of data called a blob. Rollups require data availability guarantees ensuring that data is not tampered with by a malicious actor and it was made publicly available. Currently, rollups use calldata, the cheapest form of storage in Ethereum. Compared to calldata, blobs allow more extensive storage at a lower cost. Though EVM can prove the existence of blob data, it cannot directly access it.

Once the proto-danksharding and its associated updates are in place, it is expected to increase the transaction throughput to 100,000 transactions per second and beyond (on rollups).

The Scourge

A significant threat to the decentralization of the consensus mechanism is related to Maximal Extractable Value (MEV, also called Miner Extractable Value in the context of proof of work).

MEV is a measure of profit that a validator can get from block production, other than the block reward and transaction fees, by changes in the selection and ordering of transactions in a block. There are complicated schemes to extract profit from the capability to choose the contents of the next block. It is a different skill than participating in network consensus.

Proposer/Builder Separation (PBS) is a solution proposed to solve centralization risks caused by MEV extraction. Under this scheme, the proposer (validator chosen to propose the next block) will outsource the task of block creation to builders, who try to optimize the process such that the revenue is maximum. The builders will assemble blocks and bid for proposers to select their blocks. The proposer chooses the one with the highest fee. Both builders and proposers will be rewarded.

The Scourge updates are designed to ensure reliable and credibly neutral transaction inclusion and avoid centralization and other protocol risks from MEV.

The Verge

The Verge aims to simplify the verification of blocks. It has a set of plans which can decrease the hardware requirements of validators. It introduces stateless clients that can verify blocks without downloading a local copy of Ethereum’s state, which can boost the storage requirement. These updates are mainly related to zero-knowledge (ZK) technology.

A Zero-Knowledge protocol is a method by which one party (the prover) can prove to another party (the verifier) that a given statement is true, without revealing the information itself or any additional information.

Verkle trees are proposed as an alternative for Merkle Patricia Trie, which is currently used in Ethereum. Verkle trees use vector commitments instead of hash functions in Merkle Patricia Trie. A Merkle-Patricia Trie requires more hashes as the number of child nodes increases, whereas Verkle Trees use vector commitments that allow the tree to expand without increasing the proof size. It results in shorter trees and shorter proof sizes. This will ease verification by light clients.

The Purge

This upgrade simplifies the protocol by reducing historical data using history and state expiration.

History expiration will instruct nodes to stop serving historical blocks whose age is above a limit and allow nodes to delete these from their local copy of the blockchain. The entire history becomes accessible only on demand. New nodes will follow a different syncing mechanism which will sync the chain from the most recently finalized block instead of the genesis block. Once a node is fully synced, it will not require historical data to validate future blocks.

The idea of state expiration is to prune portions of the state that have remained unused for a certain period. The pruned state will be represented by a verkle tree root that users can use to retrieve the expired state.

The expiration techniques can reduce the storage requirements for nodes and ease processing requirements on the client side. This phase also proposes changes to logs, data serialization and EVM operations.

The Splurge

This includes a set of miscellaneous updates related to various factors.

The account abstraction aims to reduce from two account types down to one, a contract account. This will allow users to choose arbitrary verification logic, like quantum-resistant signature schemes. The splurge also proposes changes to EVM.

The current plan is much different from the original concepts of sharding and Ethereum 2.0. Since Ethereum upgrades are related to technical details, plans may change over time.

References

[1] Ethereum updated roadmap

[2] Annotated Ethereum Roadmap

[3] Ethereum’s Roadmap: A Guide to The Merge and Beyond

(By Sumi Maria Abraham, Research and Development Engineer, Kerala Blockchain Academy)