Ethereum’s New Plan to Quantum-Proof Wallets Without Touching Its Code
A group of Ethereum researchers wants to protect crypto wallets from future quantum computers using tools the network already has. On June 12, 2026, they published a proposal called SPHINCS-, pronounced “SPHINCS minus,” on the Ethereum Research forum. The design lets wallets check quantum-resistant signatures directly inside the Ethereum Virtual Machine, with no protocol changes required.
A Fix Built Around Today’s Ethereum
The post credits a contributor named nicocsgy as author and thanks Vitalik Buterin among others. The problem it tackles is long-term but clear. Current blockchain wallets depend on cryptographic math that a powerful enough quantum computer could one day crack. That day isn’t here, yet Ethereum researchers are testing migration routes well before any attack becomes practical.
SPHINCS- is built to run inside the EVM as it works right now. The proposal swaps out standard SLH-DSA hash functions like SHAKE256 and uses KECCAK256 instead, which Ethereum already supports natively. Because of that swap, the verification logic can be written in Solidity. The team isn’t asking Ethereum to add new precompiles or alter its base layer. They want to see how far quantum-resistant verification can go with existing parts.
The proposal also shrinks the signing budget to fit normal wallet use. Standard designs target 2^64 signatures per key. SPHINCS- aims for a range between 2^14 and 2^20 instead. The argument is that ordinary Ethereum addresses don’t need an enormous signing budget. The post notes that the 99.9th percentile of yearly Ethereum transactions has sat near 431 per address since the Merge, which supports tighter, wallet-specific settings.
Promising Numbers, Real Limits
For its C13 variant, the proposal lists verification at about 127,000 gas with a 3,704-byte signature. It compares that against SLH-DSA-SHA2-128-24, which the post says runs at 142,000 gas, uses a 3,856-byte signature and needs approximately 1.07 billion hash calls to sign.
The researchers are upfront about the catch in their own numbers. SPHINCS- isn’t a standard and doesn’t strictly follow FIPS 205, since it relies on Keccak and a limited signing budget. Hardware wallets pose another hurdle. The C11 and C12 variants work with hardware wallets, but signing on an ST33K1M5 secure element takes 390 seconds and 47.5 seconds respectively. Fast verification doesn’t fix a slow signing experience.
Ethereum’s quantum work spans several tracks, including new signature schemes, account abstraction, migration planning, and wallet design. The Ethereum Foundation formed a dedicated post-quantum security team earlier in 2026. SPHINCS- adds one more concrete design researchers can test.