What does a zkVM designed specifically for Ethereum consensus look like? In this episode (4/6 of the @LeanEthereum miniseries), researchers from the Ethereum Foundation, Thomas Coratger (@tcoratger) and Emile, discuss with @nico_mnbl the design and implementation of leanVM, the minimal VM used for post-quantum signature aggregation. They cover: – Why leanVM uses a VM instead of fixed circuits to support flexible XMSS aggregation and recursive proof composition – The leanVM architecture: a minimal instruction set (4 opcodes) designed for simplicity and formal verification – The proving stack behind LeanVM: multilinear arithmetization, sum-check, and the Weir commitment scheme – Implementation details: CPU-optimized proving with Plonky3, SIMD techniques, and Poseidon2 hashing – Benchmarks and constraints around recursion and XMSS aggregation throughput They also discuss specification design, benchmarking methodology, and open questions around implementing post-quantum cryptography in Ethereum. Listen to the full episode. —-------------------- TIMECODES 03:36 Why LeanVM Was Chosen 07:50 LeanVM Minimalist Design 08:34 Simplicity Over Speed 19:34 Security and Field Selection 20:41 Performance and Aggregation Benchmarks 28:14 Ethereum Python Specification