GOODBYE POSEIDON: ETHEREUM PIVOTS TO SHA/BLAKE FOR POST-QUANTUM

Summary from the TLDR Crypto newsletter

The Ethereum Foundation is abandoning Poseidon after an 8-year, 8-figure investment, pivoting L1 SNARK proving to SHA2 and BLAKE2s, enabled by binary field-based SNARK designs that allow traditional hash functions to match Poseidon's efficiency without prime-field arithmetic overhead. Binary fields natively handle bit operations, cutting SNARK overhead for standard hashes to 100x vs. native CPU boolean compute, with benchmarks showing 1M hash proofs per second on a laptop. EF's post-quantum team targets a production-grade leanVM in 2027 and CL/DL/EL deployments in 2028, a transition that signals a directional shift for the zkrollup and zkVM ecosystems that currently secure billions using Poseidon. Recent attacks on lattice-based HAWK and isogeny-based SQIsign further cement SHA2 as the minimal-assumptions post-quantum primitive, removing the multi-year cryptanalysis waiting period Poseidon required before it could be trusted at scale.