Ethereum Foundation pivots post-quantum hash plan from Poseidon to SHA/BLAKE
Justin Drake tied the shift to SNARK advances and flagged a preliminary leanVM 2027 target with broader 2028 deployments.
Ethereum Foundation researcher Justin Drake said the foundation is dropping Poseidon from its planned post-quantum architecture and leaning toward established hashes like SHA or BLAKE. The change is framed as a research-direction pivot enabled by SNARK progress, with a tentative 2027–2028 path for leanVM and wider layer deployments.
Ethereum’s Post-Quantum Plan Drops Poseidon for SHA/BLAKE
Justin Drake said the Ethereum Foundation is moving away from the Poseidon hash function in its planned post-quantum architecture and turning to established alternatives such as SHA or BLAKE. This is not a mainnet parameter flip. It is a design choice inside a roadmap that is still being assembled.
The stated reason is performance, not ideology. Drake said advances in SNARKs mean conventional hashes can now perform efficiently enough to replace Poseidon in the planned systems. That is the key tell. If the proof system can carry SHA or BLAKE without blowing up prover cost, the incentive to standardize on a specialized ZK-friendly hash drops fast.
Poseidon’s role here was always forward-looking. It had been considered for future post-quantum systems such as leanVM, described as a way to help Ethereum efficiently verify large volumes of blockchain activity. Those systems have not yet been deployed on Ethereum mainnet, which keeps the market impact in the “roadmap signal” bucket rather than “immediate execution risk.”
Eigen Labs founder and CEO Sreeram Kannan added a security-and-shipping-speed framing. He said established hash-based systems have “fewer known avenues of attack” than other post-quantum approaches and could be deployed faster due to years of scrutiny. That argument is aimed at the part of the stack that breaks most often in practice: audit surface area and implementation risk, not the whitepaper.
Kannan also said joint work with the Ethereum Foundation and zero-knowledge proof company Succinct increased proving speeds by 2.5 times. The number supports feasibility for conventional-hash-based designs. The catch is the article does not specify the prover system, workload, or hardware behind the 2.5x claim, so traders should treat the magnitude as directional until benchmark conditions are disclosed.
LeanVM’s Preliminary 2027 Target and the 2028 Multi-Layer Rollout Path
Drake put dates on the direction, while labeling them as tentative. He said a production-ready leanVM is targeted for 2027, followed by deployments across Ethereum’s consensus, data and execution layers in 2028. The dates remain preliminary.
This matters because the scope is explicitly multi-layer. A post-quantum architecture that touches consensus, data, and execution is not a single EIP moment. It is a sequence of engineering and governance decisions that will need to harden over time, and the article does not describe the internal decision process beyond Drake’s statement.
The missing detail traders will want next is specificity on primitives and implementation. Drake referenced “SHA or BLAKE,” but did not specify which SHA variant or which BLAKE variant is intended for the post-quantum work. Without that, it is hard to map the pivot to concrete downstream work like circuit libraries, prover optimizations, or audit priorities.
The other open question is whether any already-shipping Ethereum components are affected. The article’s scope is clear that leanVM and related post-quantum systems are not deployed on mainnet yet, but it does not spell out whether any adjacent research tracks or tooling choices are being redirected immediately.
Why This Hash Pivot Matters for the ZK Tooling Stack Into 2027–2028
The threshold that matters is whether this stays a researcher-level direction or becomes an implementation-level commitment. If the Poseidon-to-SHA/BLAKE pivot starts showing up in code repos, draft specs, or formal roadmap communications, the tooling stack will follow, because teams build around what they expect to be audited and standardized.
I treat the 2027 leanVM target and 2028 multi-layer rollout as a schedule placeholder until the Foundation names the exact SHA or BLAKE variant and the proving benchmarks behind the claimed 2.5x speedup are reproducible. If those two pieces firm up, the pivot stops being narrative and starts becoming a real constraint on which ZK primitives and engineering bets will matter into 2027–2028.
