Ethereum Drops Poseidon for SHA/BLAKE in Post-Quantum Shift

Woofun AI reports that the Ethereum Foundation has abandoned the Poseidon hash function in its post-quantum architecture, a strategic pivot confirmed by researcher Justin Drake. The organization is now prioritizing established alternatives such as SHA or BLAKE to secure future systems. This decision marks a departure from previous plans that relied on Poseidon for efficient verification of large blockchain data volumes.

The technical rationale stems from advancements in SNARKs, compact proofs that verify computations without repeating underlying work. These improvements allow conventional hashes to perform efficiently enough to replace Poseidon in planned systems like leanVM. Although leanVM has not yet been deployed on mainnet, it is designed to help Ethereum handle massive verification loads. The shift ensures that the network can leverage mature cryptographic standards rather than experimental ones.

Per Woofun AI, the timeline for this transition remains preliminary but ambitious. A production-ready leanVM is targeted for 2027, followed by deployments across Ethereum's consensus, data, and execution layers in 2028. Industry validation supports this approach; Eigen Labs founder Sreeram Kannan noted that established hash-based systems have fewer known attack vectors. Joint work with Succinct has already increased proving speeds by 2.5 times, demonstrating the viability of this faster, scrutinized path.

This move underscores a broader trend toward security through maturity rather than novelty. By relying on SHA and BLAKE, Ethereum aims to mitigate risks associated with less-tested post-quantum methods. The successful integration of these layers will be critical for maintaining network integrity against future quantum threats. This represents a significant recalibration of the foundation's long-term security strategy.