Ethereum Foundation shifts post-quantum strategy away from Poseidon hash

The Ethereum Foundation is shifting its post-quantum security strategy away from the Poseidon hash function. After evaluating Poseidon for over a year as a potential upgrade for base-layer hashing, the foundation is now favoring more established alternatives such as SHA and BLAKE3.

Originally, Poseidon was considered a leading candidate due to its efficiency within zero-knowledge (ZK) proof systems, offering lower computational overhead and faster verification. However, researcher Justin Drake noted that recent advancements in compact proofs have eliminated Poseidon’s performance advantage, allowing more conservative and well-audited hash functions to achieve similar results.

This shift follows discussions within the Ethereum research community regarding potential security vulnerabilities in Poseidon, including concerns over preimage attacks. While the foundation previously launched a cryptanalysis program with bounties totaling up to $1 million to test the function, the decision to move toward more traditional, decades-old cryptographic standards prioritizes proven security for the network.