Ethereum Tests Post-Quantum Wallet Path Without Protocol Changes

Ethereum researchers have proposed SPHINCS-, a post-quantum signature design that could let wallets verify quantum-resistant signatures inside the EVM without any protocol changes.

The proposal, published on Ethereum Research on June 12th, credits nicocsgy as the author and special thanks to Vitalik Buterin and other contributors.

SPHINCS- is a stateless post-quantum signature verification scheme optimized for the Ethereum Virtual Machine. It uses KECCAK256 instead of standard SHAKE256 to work inside the existing EVM, and its C13 variant lists at about 127,000 gas with a 3,704-byte signature.

The proposal narrows the signature budget to fit ordinary blockchain wallets, rather than keeping the broader standard target of 2^64 signatures per key. It argues that normal Ethereum addresses do not need an unlimited signing budget, citing the average annual 99.9th percentile of Ethereum transactions has been about 431 per address since the Merge.