Ethereum L1 drops Poseidon in post-quantum move

Ethereum Foundation researcher Justin Drake has said the network’s layer 1 will leave Poseidon after an eight-year, eight-figure research effort and pursue established hash functions such as SHA-2 or BLAKE2s. Summary Ethereum’s L1 roadmap will use traditional hashes instead of the SNARK-focused Poseidon function. Binary-field SNARKs can reportedly prove about 1 million traditional hash calls per second. A production-grade leanVM is scheduled for 2027, followed by layer deployments in 2028. Hash-based signatures form a central part of Ethereum’s planned protection against quantum computers. Ethereum L1 turns away from Poseidon Justin Drake said in an Aug. 13 X post that the Ethereum Foundation is abandoning Poseidon for its L1 roadmap and moving toward traditional options such as SHA or BLAKE. “Goodbye, Poseidon!” Drake wrote, describing the decision as the result of an “8-year, 8-figure rabbit hole” in post-quantum cryptography. Goodbye, Poseidon! 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… — Justin Drake (@drakefjustin) August 13, 2026 Poseidon emerged in 2019 as a hash function designed for zero-knowledge proof systems. Its structure made it less costly to process inside Succinct Non-Interactive Arguments of Knowledge, commonly known as SNARKs, than traditional hash functions built around binary operations. Since 2018, the Ethereum Foundation has invested in specialized hashes as part of its work on zero-knowledge technology. Poseidon later became a common choice across zk-rollups and zkVMs, including systems that secure billions of dollars in crypto assets. You might also like: Is Ethereum losing the L1 race to Solana? Drake’s announcement concerns Ethereum’s future L1 architecture, rather than an immediate removal of Poseidon from existing applications. Rollups, virtual machines, and other projects that already use the function are not required to replace it because of the roadmap decision. Advances in proof-system design have now changed the trade-off that initially favored Poseidon. According to Drake, established functions such as SHA-2 and BLAKE2s can match its performance when paired with SNARKs designed around binary computation. “In hindsight the key was not SNARK-friendly hashes, but hash-friendly SNARKs.” Binary-field SNARKs make traditional hashes practical Binary fields allow proof systems to process the Boolean logic used by standard hash functions more naturally. Earlier SNARK designs often relied on large prime fields, where bit-based operations such as XOR could be costly to represent. Working over the smallest prime number, two, allows binary-field systems to align their calculations with the zeros and ones used in conventional computing. Drake said the resulting designs can prove about 1 million traditional hash calls per second on a laptop, with an overhead of roughly 100 times compared with native CPU execution.