# Ethereum Researchers Drop the Poseidon Hash From the Chain's Next Base Layer

Justin Drake, an Ethereum Foundation researcher, said proof systems built over binary fields can now prove roughly a million conventional hash calls per second, removing the case for running a specialized, less-studied hash inside Ethereum's future proving stack.

- Published: 2026-08-15T05:40:49.580Z
- Canonical: https://polylog.news/crypto/2026-08-15/ethereum-researchers-drop-the-poseidon-hash-from-the-chain-s
- Publisher: Polylog (Crypto desk)
- Section: crypto
- Sources: [CryptoSlate](https://cryptoslate.com/ethereum-abandons-its-8-year-cryptography-bet-after-proof-systems-flip-the-tradeoff/), [crypto.news](https://crypto.news/ethereum-l1-drops-poseidon-in-post-quantum-move/), [Coin Turk](https://en.coin-turk.com/ethereum-foundation-scraps-poseidon-hash-for-2027-base-layer-amid-proof-system-advances/)

Ethereum Foundation researcher Justin Drake confirmed on August 13 that the foundation's plans for a future base layer will [no longer rely on Poseidon](https://cryptoslate.com/ethereum-abandons-its-8-year-cryptography-bet-after-proof-systems-flip-the-tradeoff/), the hash function designed in 2019 specifically to be cheap to verify inside zero-knowledge proofs. The design will instead use members of the SHA and BLAKE families, the conventional hash functions that have absorbed decades of public cryptanalysis.

The reason is a change in the underlying proving technology, not a flaw found in Poseidon. Proof systems that operate over binary fields have become fast enough to handle the bit-level operations that conventional hash functions perform, the very operations Poseidon was designed to avoid. Reported figures put binary-field systems at roughly one million conventional hash calls proved per second, and joint work between the foundation and the proving company Succinct raised proving speed by about 2.5 times. Once that cost gap closes, the case for using a newer, more specialized hash function instead of a long-studied one closes with it.

The decision sits inside the leanVM effort, the simplified execution and proving design intended to let Ethereum verify large volumes of activity with a small, formally tractable core. A production leanVM is scheduled for 2027, with layer deployments in 2028. Hash functions matter far beyond speed in this design, because [post-quantum signature schemes](https://crypto.news/ethereum-l1-drops-poseidon-in-post-quantum-move/) are built almost entirely from hash functions, so the hash chosen for the base layer becomes the security assumption behind the chain's long-term resistance to quantum attack.

No one involved claims Poseidon is broken. The [foundation's position](https://en.coin-turk.com/ethereum-foundation-scraps-poseidon-hash-for-2027-base-layer-amid-proof-system-advances/), as reported, is that the tradeoff that justified using Poseidon has shifted. That is the conservative choice: consensus-critical code inherits the weakest primitive built into it, and a primitive with seven years of scrutiny carries more unknown risk than one with thirty.

## What this means

Ethereum is removing a novel cryptographic dependency from the layer that secures the largest pool of on-chain value, $41.15 billion in decentralized finance funds locked on Ethereum out of $75.08 billion across all chains, according to DeFiLlama. The teams exposed are the ones that built proving stacks, hardware accelerators and circuit libraries around Poseidon, since the base-layer target they optimized for is being replaced. The gain goes to proving companies working on binary-field systems, whose technology is now the assumption the roadmap rests on rather than one option among several.

## What to watch

- Whether zero-knowledge rollups that use Poseidon internally follow the base layer or keep their own hash, because divergence means proof-verification costs and audit surfaces split across the ecosystem.
- Published benchmarks for binary-field provers on SHA and BLAKE workloads from independent teams, which would confirm or undercut the performance claim the decision rests on.
- The leanVM specification milestones through 2027, since slippage there pushes the post-quantum signature work that depends on the hash choice further out.