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Ethereum protocol upgradesEthereum Foundation—Lean EthereumEthereum Foundation—Ethereum protocol upgradesEthereum Foundation—Lean EthereumEthereum Foundation—

Lean Ethereum

by Ethereum FoundationCH

ResearchStage 1 of 5

Research and prototype software; no mainnet timeline.

Updated 13 Aug 2026Checked 25 Sep0 updates this week

Milestones

Next · Prototype clients and test networks
  1. Beam chain proposal presented at DevconNov 2024Complete.
  2. Lean Ethereum vision publishedJul 2025Complete.
  3. Prototype clients and test networksNowCurrent milestone.

Most important updates

  • 13 Aug 2026
  • 23 Jan 2026
  • 31 Jul 2025
  • 12 Nov 2024

Upcoming

  1. 2027Production-grade leanVM targeted, per Justin Drake; layer deployments planned from 2028 (next)

Current obstacles

  • Combining post-quantum signaturesPost-quantum signatures are large and can't be merged like today's. ZK proofs are needed to keep blocks small.

Physics limits

  • Post-quantum signatures are bigA hash-based signature is a few kilobytes, roughly 30x a 96-byte BLS signature today. With hundreds of thousands of validators voting, raw signatures would swamp bandwidth unless proofs compress them.
  • Proving costs far more than computingA zero-knowledge proof takes thousands of times more computation than the work it proves. Proving each block in real time needs specialised hardware, which pulls proving toward a few operators.
  • Quantum search halves hash securityGrover's algorithm lets a quantum computer search in the square root of the steps, so a 256-bit hash gives about 128-bit security. Hash-based designs must size outputs with that in mind.

How it works

4 parts
A GeForce RTX 5090 graphics card: provers run on GPUs like this to compress thousands of signatures, or a whole block, into one short proof
A GeForce RTX 5090 graphics card: provers run on GPUs like this to compress thousands of signatures, or a whole block, into one short proofPhoto: PantheraLeo1359531 · CC BY 4.0 (opens commons.wikimedia.org)
Signatures

Hash-based signatures

Today's validator signatures rely on elliptic curves, which a big quantum computer could break. Lean Ethereum swaps them for signatures built only from hashes.

Aggregation

Proofs squeeze many signatures

Hash-based signatures are kilobytes each and can't be merged. A small proving system (leanVM) proves thousands were valid in one short proof.

Finality

Seconds, not minutes

The Beam chain proposal aimed for 4-second slots and finality within a few slots, instead of ~13 minutes today, using a simpler voting protocol.

Verification

Blocks checked by proofs

Nodes would check a succinct ZK proof of each block instead of re-running every transaction, so even small devices can verify the chain.

Papers & demos

1 item
  1. Jul 2025blog
    Lean Ethereum (opens blog.ethereum.org)Long-term redesign: post-quantum signatures, faster finality and blocks checked by ZK proofs.

Update log

4 updates

Thu 13 Aug

  • Major: PressResearch

Fri 23 Jan

  • Minor: PressPeople

Thu 31 Jul 2025

  • Major: PressResearch

Tue 12 Nov 2024

  • Major: PressResearch

About Ethereum Foundation

The team behind Lean Ethereum

Ethereum Foundation

Ethereum research and upgrades

Swiss non-profit that funds research and coordinates upgrades to Ethereum, the largest blockchain for smart contracts. It doesn't control the network: independent software teams ship each upgrade. Its plan is to scale through rollups while keeping it cheap to run a validator at home.

  • The Merge (15 Sept 2022) switched Ethereum to proof of stake, cutting energy use by ~99.9%.
  • Fusaka (Dec 2025) lets nodes check rollup data by sampling pieces instead of downloading it all.
  • Glamsterdam, the next upgrade, is on test networks, with mainnet targeted for late 2026.

ethereum.foundation (opens ethereum.foundation)Company profile →

Founded
201412 yrs
Headquarters
Switzerland
Status
Private
Valuation
private
Works in
CryptoBlockchains (L1s)
Coverage
2 programs · 11 updateslatest 3 Sep 2026checked 25 Sep
Partners
Coinbase (Base)Eigen LabsStarkWare
People
Vitalik Buterin (opens en.wikipedia.org)Co-founder of EthereumAya MiyaguchiPresidentHsiao-Wei WangCo-Executive Director
Primer