Ethereum Foundation pivots away from Poseidon in post-quantum plan

Hash function switch

Advances in compact proofs have erased Poseidon’s previous performance advantage, according to researcher Justin Drake.

The Ethereum Foundation is moving away from the Poseidon hash function in its planned post-quantum architecture, according to Drake. On Thursday, Drake said the foundation was abandoning Poseidon and turning to established alternatives such as SHA or BLAKE.

A hash function converts data into a fixed digital fingerprint, enabling computers to check that information has not been altered. Poseidon had been considered for future post-quantum systems such as leanVM, which would help Ethereum efficiently verify large volumes of blockchain activity. Those systems have not yet been deployed on mainnet.

Why conventional hashes now work

Drake said advances in SNARKs, which are compact proofs used to confirm computations without repeating underlying work, mean conventional hashes can now perform efficiently enough to replace Poseidon in those planned systems.

Timeline

He said a production-ready leanVM is targeted for 2027, followed by deployments across Ethereum’s consensus, data and execution layers in 2028. The dates remain preliminary.

Hash-based systems

Eigen Labs founder and CEO Sreeram Kannan said established hash-based systems have fewer known avenues of attack than other post-quantum approaches and could be deployed faster because they have already undergone years of scrutiny. Kannan said joint work with the foundation and zero-knowledge proof company Succinct had increased proving speeds by 2.5 times.

Related: Vitalik Buterin outlines quantum resistance roadmap for Ethereum