Ethereum Abandons Poseidon Hash Function for SHA or BLAKE

The Ethereum Foundation has made a significant decision to pivot away from the Poseidon hash function and towards SHA or BLAKE for its Layer 1 roadmap. According to Justin Drake, an Ethereum researcher, this change is a result of progress in binary-field SNARK design, which allows traditional hashes like SHA-2 and BLAKE2s to match the performance of Poseidon's SNARK.

This decision has implications for Ethereum's post-quantum cryptography roadmap. Hash-based signatures are considered quantum-resistant but too bulky for Ethereum's current scale. SNARK aggregation offers a workaround, compressing many signatures into a single compact proof.

The Ethereum Foundation plans to implement a production-grade leanVM in 2027 and deploy it across the consensus, data, and execution layers in 2028. This move signals that Ethereum is rebuilding its long-term security architecture around cryptography that has already survived decades of outside scrutiny.