SNARK-Based Aggregation: Restoring Scalability in a Post-Quantum Consensus

Post-quantum signatures are larger and lack BLS’s native aggregation properties. This creates a scalability challenge for Ethereum’s consensus layer, where thousands of validator signatures must be efficiently combined.

The aggregation problem

BLS signatures can be aggregated into a single signature regardless of how many signers participated. This property does not exist for any known post-quantum signature scheme.

Without aggregation, post-quantum consensus would require transmitting and verifying individual signatures from each validator — an approach that does not scale.

leanMultisig: a minimal zkVM approach

leanMultisig takes a different approach. Instead of relying on algebraic aggregation, it uses a minimal zero-knowledge virtual machine (leanVM) to prove that a set of hash-based signatures are all valid.

The resulting proof is compact and can be verified efficiently, restoring the scalability properties that BLS aggregation provides today.

Why this matters

Without a viable aggregation strategy, the post-quantum transition would force difficult trade-offs between security and performance. leanMultisig demonstrates that these trade-offs can be avoided.