On Thursday (13), researcher Justin Drake announced that the Ethereum Foundation has discarded the use of the Poseidon hash function in its planned post-quantum architecture. Instead, the foundation will adopt established alternatives such as SHA or BLAKE.
Poseidon had been considered for future post-quantum systems such as leanVM, which would help Ethereum efficiently verify large volumes of activity on the blockchain. These systems have not yet been deployed on the mainnet.
Drake said that advances in SNARKs, compact proofs used to confirm computations without repeating the underlying work, eliminated Poseidon's performance advantage. As a result, conventional hashes have become efficient enough to replace it.
The researcher said a production-ready leanVM is expected in 2027, followed by deployments in Ethereum's consensus, data, and execution layers in 2028. The dates are still preliminary.
Eigen Labs founder and CEO Sreeram Kannan said that systems based on traditional hashes have fewer known attack vectors than other post-quantum approaches and could be deployed more quickly, as they have already undergone years of scrutiny. According to Kannan, the joint work with the foundation and zero-knowledge proof company Succinct increased proof speed by 2.5 times.
