Ethereum Moves to New Hash Functions for Post-Quantum Security

The Ethereum Foundation is stepping away from the Poseidon hash function for its planned post-quantum architecture and is instead considering more established alternatives such as SHA or BLAKE, according to Ethereum researcher Justin Drake.

A hash function transforms data into a fixed digital fingerprint, allowing computers to verify that information has not been modified. Poseidon had previously been considered for future post-quantum systems such as leanVM, which is intended to help Ethereum efficiently verify large amounts of blockchain activity. These systems have not yet been deployed on Ethereum mainnet.

Ethereum turns to established hash functions

Drake said recent progress in SNARK technology has changed the trade-offs involved. SNARKs are compact cryptographic proofs that allow computations to be verified without repeating the underlying work. According to Drake, improvements in SNARK performance mean conventional hash functions can now operate efficiently enough to replace Poseidon in Ethereum’s planned architecture.

The Ethereum Foundation is targeting a production-ready version of leanVM for 2027, with potential deployments across Ethereum’s consensus, data and execution layers following in 2028. However, these timelines remain preliminary.

Post-quantum development advances

Eigen Labs founder and CEO Sreeram Kannan said established hash-based systems have fewer known avenues of attack than some alternative post-quantum approaches. Their longer history of scrutiny could also allow them to be deployed more quickly. Kannan also said collaborative work involving Eigen Labs, the Ethereum Foundation and zero-knowledge proof company Succinct had improved proving speeds by 2.5 times.

Sources:

https://cointelegraph.com/news/ethereum-foundation-drops-poseidon-post-quantum-plan

https://x.com/sreeramkannan/status/2087947941604688009

https://x.com/drakefjustin/status/2087905684180418733