Ethereum Pivots to SHA and BLAKE for Post-Quantum L1

Ethereum had considered Poseidon, a hash function optimized for SNARKs, as a core primitive for its layer-1 overhaul. Its efficiency came with a trade-off: Poseidon is younger and less battle-tested than SHA or BLAKE. The Ethereum Foundation formed a dedicated Post-Quantum Security team in January 2026 and has targeted roughly 2029 for core quantum-resistant infrastructure, making the choice of hash function central to Ethereum’s security and proving roadmap.

The foundation is now steering L1 toward established hashes including SHA and BLAKE, reducing reliance on newer algebraic designs as AI-assisted cryptanalysis advances. Flock, a binary-field, post-quantum SNARK disclosed on July 29, proved 82,100 BLAKE3 or 42,100 SHA-256 compressions per second on one Apple M4 Max core. Ten-core throughput reached 661,000 for BLAKE3 and 338,000 for SHA-256, making conventional hashes practical for Ethereum-scale proofs. No mainnet deployment date has been announced.