Ethereum Missing Key Element ‘Poseidon Hash’ in zkEVM Privacy Push, Developer Claims

A renowned developer on X, Ameen Soleimani, has criticized the reluctance of Ethereum to implement the Poseidon precompile. In an update shared recently, Soleimani expressed concerns over Ethereum’s hesitation to implement this hash function, which is necessary for efficient zk proofs.

Insight into Poseidon precompile delays

According to Soleimani, this same function has been on other blockchains such as Solana, Starknet and Stellar since 2020-2022. He criticized the Ethereum community for always talking about “privacy by default” but refusing to make the required technical upgrade that would guarantee it.

Soleimani insists that the key element, which is the zkEVM feature, is missing, and if conditions stay that way, privacy is not be truly enabled on Ethereum.

The developer claimed that the team at Starknet tried to offer some level of assistance to the Ethereum chain but was waved off. Soleimani insists that Ethereum has a privacy gap and appears to be a call to action to the Ethereum team.

He opines that Ethereum needs to match up with the current zk rollup demands and improve its chain. Notably, EIP-5988 has been proposed since 2022 to add Poseidon to EVM addresses, but it has not happened. The development remains stagnant, and it is causing delays to native shielded transfers.

It is important to clarify that a “precompile” is a built-in, low-cost function that could significantly reduce gas fees on Ethereum. So, Ethereum’s continued use of Poseidon without a precompile makes privacy on apps impractical on layer 1.

Soleimani argued that Poseidon is already the “most battle-tested’ hash function, enjoying utility on zk systems. Given its reliability, he opined that there is no genuinely acceptable reason to delay the deployment.

He decried Ethereum’s roadmap, which has continued to push privacy to layer 2s instead of layer 1s owning it. Soleimani wants layer 1s to still have core zk primitives because, without them, private transaction costs will remain too expensive.

Privacy roadmap promises clash with slow implementation

The developer’s arguments have a basis, considering that Ethereum founder Vitalik Buterin had, in April 2025, outlined a new roadmap on privacy.

Despite promises to get serious, implementation remains a challenge and has continued to be a matter sparing debates in the space.

Recognizing the cost-prohibitive nature of privacy functions on Ethereum, Ernst & Young’s Paul Brody expressed hope that the blockchain might actually act in 2026. Brody stated that he desires to see privacy implementation becoming mainstream for users and institutions.