- Ethereum is abandoning the bespoke Poseidon hash after eight years in favor of battle-tested algorithms.
- Developers have chosen SHA and BLAKE.
- This move is tied to the blockchain’s post-quantum security.
The Ethereum Foundation has decided to stop using the Poseidon hash function in Ethereum’s future Layer 1 architecture and switch to the traditional SHA or BLAKE algorithms. Ethereum Foundation researcher Justin Drake announced this, calling the decision the result of eight years of cryptography research and an important milestone in preparing the blockchain for the post-quantum era.
Goodbye, Poseidon!
— Justin Drake (@drakefjustin) August 13, 2026
An epic 8-year, 8-figure rabbit hole in post-quantum cryptography reaches its dream conclusion. The Ethereum Foundation is abandoning Poseidon for L1, pivoting to SHA or BLAKE. This milestone unlocks ultimate security for lean Ethereum and foreshadows a golden…
Poseidon has long been considered one of the key SNARK-friendly hashes — algorithms optimized for use in zero-knowledge proof systems. According to Drake, new research has shown that traditional SHA2 and BLAKE2s can achieve comparable SNARK efficiency by using binary fields.
Ethereum Reassesses Poseidon’s Role
Drake noted that since 2018, the Ethereum Foundation has invested significant resources in developing specialized hash functions for SNARKs, and Poseidon later became one of the dominant solutions in this category. At the same time, new SNARK constructions have shown that the hash function itself does not necessarily need to be specially optimized for proofs.
“In hindsight the key was not SNARK-friendly hashes, but hash-friendly SNARKs,” the researcher wrote.
This refers to the use of so-called binary fields, which operate directly on bitwise operations. This allows traditional hash functions, including SHA and BLAKE, to run more efficiently inside proof systems.
Ethereum Research also noted that Ethereum’s modern cryptographic development views SHA and BLAKE3 as more mature, from a cryptanalysis standpoint, alternatives to Poseidon.
Drake cited a figure of around 1 million traditional hash calls per second, which, he said, can be proven on a laptop, with overhead of roughly 100x compared with native CPU bitwise operations.
Post-Quantum Security for Ethereum
The shift is tied to Ethereum’s broader work on post-quantum cryptography. Ethereum’s current signature mechanisms — including ECDSA for user accounts and BLS for validators — are potentially vulnerable to future quantum computers, so developers are already working on a transition to post-quantum schemes.
In June 2026, Ethereum Foundation researchers, including Justin Drake, described a separate design space for a post-quantum registry of validators’ public keys. They also stressed that the transition from BLS to post-quantum signatures would happen in stages.
According to Drake, the new approach should also speed up the rollout of post-quantum architecture. The current plan calls for a production version of leanVM in 2027, with the changes rolling out across the consensus, data availability, and execution layers in 2028.
As a reminder, moving away from Poseidon in favor of SHA or BLAKE for the future L1 architecture aligns with Vitalik Buterin’s broader idea of simplifying and improving the efficiency of Ethereum’s base layer. In particular, Buterin proposed gradually replacing the EVM with RISC-V to make execution more amenable to zero-knowledge proofs.
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