A researcher from the Ethereum Foundation’s Kohaku privacy project, known as Nico, has outlined a method to fortify Ethereum accounts against future quantum computing threats without requiring a network-wide hard fork. In a recent statement, Nico emphasized that the Ethereum network can begin implementing quantum-resistant measures for individual accounts at an estimated cost of just $0.07 per account. This approach leverages smart contract technology to add a layer of post-quantum protection, allowing users and wallet developers to act independently while the broader Ethereum ecosystem continues to develop long-term protocol upgrades.
At the heart of this initiative is SPHINCS-, a family of stateless, hash-based signature schemes optimized for the Ethereum Virtual Machine (EVM). Derived from the SPHINCS+ framework and recent advances in compact hash-based cryptography, SPHINCS- aims to verify post-quantum signatures on-chain without the need for new precompiles or changes to Ethereum’s core rules. Nico’s technical work demonstrates that a Solidity-based verifier can already validate these signatures at a practical cost—one variant, named C13, requires approximately 127,000 gas and a signature size of 3,704 bytes. The research also incorporates a formal proof in Lean 4 via Verity, though Nico notes that further audits are pending, with an initial review already completed by Fable.
The significance of this development lies in Ethereum’s current reliance on ECDSA signatures, which are vulnerable to sufficiently advanced quantum computers. By adopting hash-based signatures, SPHINCS- offers a robust defense against such attacks. This proposal aligns with Ethereum’s broader roadmap, as outlined by co-founder Vitalik Buterin, which prioritizes privacy, security, and post-quantum readiness. Buterin has previously highlighted account abstraction as a key component of short-term privacy plans, and the SPHINCS- approach dovetails with that vision by enabling wallets to integrate quantum-resistant signature schemes without waiting for protocol-level changes.
Nico’s work also acknowledges limitations, including non-standard parameter settings, bounded signature counts, and deviations from NIST-aligned designs. These factors underscore that the current proposal is a proof of concept rather than a final solution. Nonetheless, it offers a practical pathway for high-value accounts to begin testing quantum-resistant protections now, at a cost low enough for widespread experimentation. This account-level defense does not imply an imminent quantum threat but rather a proactive step to safeguard assets before Ethereum enacts more comprehensive upgrades through future technical proposals and community review.