Ethereum Ditches Poseidon for Traditional Hashes in Post-Quantum Move

Ethereum's Layer 1 (L1) roadmap will no longer use Poseidon, a specialized hash function designed for zero-knowledge proof systems. After an eight-year, $8-figure research effort, the Ethereum Foundation has decided to switch to established hash functions like SHA-2 or BLAKE2s. This decision is part of the foundation's post-quantum security program, which aims to prepare the protocol for computers capable of breaking elliptic-curve cryptography.

According to Justin Drake, an Ethereum Foundation researcher, the decision was made due to advances in proof-system design that have changed the trade-off between Poseidon and traditional hash functions. He stated that established functions can now match Poseidon's performance when paired with SNARKs designed around binary computation.

The use of binary-field SNARKs allows for more efficient processing of traditional hashes, making them practical for Ethereum's L1 architecture. This change is expected to reduce the network's reliance on specialized cryptographic functions that require years of separate analysis.