Ethereum Abandons Custom Hash Function in Favor of Battle-Tested Algorithms

The Ethereum Foundation has made a significant decision to abandon its bespoke Poseidon hash function after eight years, opting for more battle-tested algorithms instead. According to researcher Justin Drake, this move is tied to the blockchain's post-quantum security efforts and will provide ultimate security for the lean version of Ethereum.

The researchers have chosen SHA and BLAKE as their new cryptographic strategy, citing that traditional hash functions can achieve comparable SNARK efficiency by using binary fields. This shift away from Poseidon has been years in the making, with significant resources invested in developing specialized hash functions for SNARKs since 2018.

The decision is also seen as a step towards simplifying and improving the efficiency of Ethereum's base layer, aligning with Vitalik Buterin's broader idea. The new approach will speed up the rollout of post-quantum architecture, with a production version of leanVM expected in 2027 and changes rolling out across the consensus, data availability, and execution layers in 2028.