LambdaClass Blog

ethrex

ethrex completes its first external security audit

ethrex, our Ethereum execution client, has completed its first external security audit. Least Authority reviewed the client between January and May 2026 and identified 20 issues and 8 suggestions. The final report, delivered on May 4, verified that every issue was addressed. Both reports are published in the repository. What

ethlambda

ethlambda: devnet 5 and beyond

We already introduced ethlambda, our Lean Consensus client. We also wrote a blog post about devnet 4, which introduced recursive aggregation. Now that devnet 5 is implemented and in interop testing, it's a good time to recap the devnets so far and look at the candidates for the

All the ways lead to Rome: a summary of our trip to Eurocrypt, zkSummit, and zkProof

During the last two weeks, cryptographic research moved to Rome with a host of events: May 7th featured the return of zkSummit 14, May 9th-10th had zkProof 8 and several Eurocrypt side-events and from the 11th until the 13th Eurocrypt 2026 took place. Lambda, together with Aligned, and

Goldfish: the forgetful fork-choice

In a previous post, we explained how LMD-GHOST worked. This post is about its problems, and how Goldfish fixes them. Latest Message Driven GHOST (LMD-GHOST) is the fork-choice rule of Ethereum's beacon chain. Balancing attacks were found, exploiting a lack of coordination inherent in the

A Week Above the Arctic Circle: ethrex at Soldøgn Interop

Last week, just over a hundred Ethereum core contributors gathered in Longyearbyen, Svalbard, for the Soldøgn interop: a single-track week of focused, multi-client work on the Glamsterdam network upgrade, above the 78th parallel, under a sun that never set. It was our first interop as a participating client.

The Road to Networking Stability

Stakers told us they want to switch between execution clients without friction, sometimes leaving a node off for several days before switching back. Over the last month we shipped a series of fixes across ethrex's P2P stack. Restarts are more reliable. Bandwidth consumption dropped by a meaningful factor

ethlambda: how we got a 3x speedup in signature aggregation

Devnet 4 of the post-quantum leanConsensus testnet introduced recursive signature aggregation through leanMultisig. The change is good for the network (fewer proofs to verify per block), but it pushed enough work onto aggregators that our node started missing slots and slipping on finalization. Two changes got us back to

ethlambda

Finality in leanConsensus: How ethlambda Implements 3SF-mini

In our previous post, we covered how ethlambda uses LMD-GHOST and ended with an open question: how does the protocol decide when a block is permanent and the chain tip can no longer be reorged? This post covers the other half of consensus: 3-Slot Finality, minimal version.

Actor Model

Introducing Spawned: Erlang-Style Actors for Rust

Check out Spawned, our take on a concurrency framework in Rust inspired by the battle-tested design of the actor model implemented in Erlang in which your business logic is plain Rust methods, no explicit channels, mutexes, or concurrency primitives.

Rust

libssz: a blazing fast, zkVM-friendly SSZ Rust library

SSZ (Simple Serialize) is the serialization and Merkleization format of Ethereum's consensus layer. We present a new implementation in Rust that fills a niche: fast and zkVM friendly.

lean

The hitchhiker's guide to reading Lean 4 theorems

Claude can generate Lean code all day long, but eventually you have to read the code and more importantly, the theorems verifying the software's correctness properties. Learn how to read Lean theorems in this short guide.

tekton

Tekton: deploying AI Agents at scale for the next generation of software development

AI is now good enough to tackle most software but it is not yet perfect. The challenge is to leverage AI to increase our productivity without sacrificing quality or safety; keeping humans in the loop, increasing visibility, reducing friction and adding guardrails.

lean ethereum

Fork Choice in leanConsensus: How ethlambda Implements LMD-GHOST

This is a follow-up to our posts on ethlambda's architecture. Here we explain the two core consensus mechanisms that ethlambda implements: LMD-GHOST for fork choice and 3SF-mini for finality.

ethereum

How ethrex Heals State During Snap Sync

How does snap sync ensure lower sync times for Ethereum nodes joining the network? We go into Ethrex's implementation in depth.

lean

Verified Code Optimization in Lean 4: How Equality Saturation Generates Proven-Correct C Code with Truth Research ZK

Our experiments with Lean and formal verification continue to bear fruit. To further our knowhow and experience, we set out to see if we could apply Lean's strengths to a more advanced topic: compiler optimizations. Traditional verified compilers focus on semantic preservation of already-written C code, limiting

ethereum

Building a Minimalist Post-Quantum Ethereum Client: ethlambda's Architecture

This is a follow-up to our post on building a post-quantum Ethereum client. Here we detail ethlambda's minimalist architecture.

ecdsa

Ethereum Signature Schemes Explained: ECDSA, BLS, XMSS, and Post-Quantum leanSig with Rust Code Examples

A complete guide to the mathematics, code, attacks, and future of cryptographic signatures in Ethereum.

ethereum

Ethlambda: Building a post-quantum Ethereum client with the help of shared tooling

This is a follow-up to our introduction of ethlambda, in which we cover what a Lean Consensus client consists of and what tooling facilitates its development.

ethrex

How We Made an Ethereum Rust Execution Engine 20x Faster: Profiling-Driven Optimization

Over the past months, the ethrex team has been relentlessly focused on performance optimization. Through systematic profiling, targeted improvements, and architectural changes, we've achieved a 20x improvement in block execution throughput.

Updated roadmap and priorities for lambdaworks for 2026

Introduction It's been nearly 3 years since we started lambdaworks, our cryptographic library for zero-knowledge proofs. The first PR was merged on January 18th 2023 and since then we had over 575 PRs merged from almost 80 collaborators and counting. At that time, there was still a

If It Compiles, It Is Correct: A Practical Introduction to Lean 4 for Engineers

Introduction At LambdaClass, we've been exploring Lean 4 as a tool for formal verification in zero-knowledge proof systems and in formalizing the kernel of Concrete. As the ZK ecosystem matures, the stakes for correctness have never been higher: a single bug in a zkVM or proof system

Featured

Ethereum Agent: a typescript SDK designed for agents to operate autonomously in Ethereum

Ethereum emerged as a general purpose financial backend reducing the cost and complexity of building financial services while improving their speed and security. For decades the internet accelerated communication but did not create a neutral system for defining ownership or enforcing obligations. Ethereum solves these problems by embedding them in

ethereum

Ethrex L2: A Different Approach to Building Rollups

We present Ethrex L2, a rollup stack built with a different set of priorities: simplicity, minimalism, and modularity.

ethereum

An interview with Drew Van der Werff, creator of the latest, most important public good of Ethereum

We interviewed Drew Van der Werff on Commit Boost, a new Ethereum validator sidecar focused on standardizing the communication between validators and third-party protocols.

ethereum

Introducing ethlambda: A Lean Consensus Client for Ethereum's Next Era

At LambdaClass we have been working on an Ethereum Lean Consensus client called ethlambda. As Ethereum prepares for its most ambitious consensus layer redesign since the Merge, client diversity will be more important than ever.