Ethereum Leader Says Quantum-Proof Accounts Cost Just 7 Cents

Ethereum developers are exploring a path to protect accounts from future quantum-computing threats without waiting for a costly network upgrade. According to Ethereum Foundation researcher Nicolas Consigny, the “Kohaku” project lead, Ethereum could begin adding post-quantum protections at an estimated cost of as little as $0.07 per action, leveraging a new on-EVM approach rather than a hard fork.

Consigny shared details in an X post on Saturday and pointed to a corresponding research write-up on Ethresear.ch. The proposal adapts SPHINCS+, a post-quantum signature scheme standardized by the U.S. National Institute of Standards and Technology (NIST), to make onchain verification cheaper on Ethereum. The work is framed as a stepping stone toward a future, more optimized design called “leanSPHINCS.”

Key takeaways

• Ethereum Foundation research proposes “SPHINCS-,” an adaptation of SPHINCS+ aimed at reducing onchain post-quantum signature verification costs.
• The approach is intended to work without requiring a protocol hard fork and without relying on a new precompile.
• Consigny describes SPHINCS- as an intermediate bridge toward “leanSPHINCS,” which targets even lower costs via signature aggregation.
• The motivation is long-term quantum risk to Ethereum’s current reliance on elliptic-curve cryptography for signatures.

From NIST post-quantum signatures to “SPHINCS-” on the EVM

In his Saturday post, Consigny outlined a proposal that takes SPHINCS+—a post-quantum signature standard—then modifies how it can be verified in an Ethereum smart-contract environment. The core claim is that the updated scheme can cut the onchain verification burden, allowing post-quantum protections to be introduced earlier than would be feasible with a full protocol change.

The paper describes the method as “SPHINCS-,” emphasizing that the goal is cost reduction on the EVM while keeping deployment practical. Consigny specifically positioned it as something that could be used before a dedicated hard fork is ready, which matters for an ecosystem where upgrading cryptographic primitives typically involves coordination, tooling updates, and migration planning.

Equally important, the proposal is not framed as a final destination. Consigny described SPHINCS- as a “bridge” toward “leanSPHINCS,” a future system intended to further lower verification costs by aggregating signatures—an efficiency technique that could reduce the amount of work required per verified authorization.

Why Ethereum is moving early on quantum-resistant accounts

Ethereum’s account security today depends on digital signatures tied to elliptic-curve cryptography. While quantum computers powerful enough to break widely used elliptic-curve schemes do not exist at the scale required in practice, the industry is preparing for a scenario where cryptographic assumptions change.

Consigny’s proposal is aimed at reducing exposure over time by introducing post-quantum protections before Ethereum has a full, consensus-level replacement of its signature layer. In that sense, the research is less about replacing everything immediately and more about building optional, deployable defenses that can become more common as better efficiency techniques—like the leanSPHINCS direction—mature.

The cost figure Consigny referenced—potentially as low as $0.07—signals a practical constraint: even if a cryptographic approach is theoretically correct, it may fail to gain traction if it is too expensive to verify onchain. By focusing on verification cost and deployment path (no hard fork, no precompile), the work tries to address that adoption barrier directly.

Quantum research outside Ethereum also underscores the urgency

The push toward quantum-resistant cryptography is not happening in isolation. Earlier coverage highlighted real-world proof-of-concept research demonstrating that quantum algorithms can threaten certain elliptic-curve constructions under specific conditions. In April, post-quantum startup Project Eleven awarded a prize to researcher Giancarlo Lelli for using a quantum computer to break a 15-bit elliptic-curve key, using a variant of Shor’s algorithm.

Bitcoin is often used as the contrasting example because it relies on 256-bit elliptic-curve keys, which are far larger than the small key size used in the demonstration. Still, the episode fed broader discussions on whether the academic-to-practical gap for quantum attacks could close faster than many expect.

Glassnode’s analysis, as cited in the same broader conversation, suggested that a meaningful portion of Bitcoin could be “unsafe” in a future quantum attack scenario based on key exposure and address/key management practices. According to that reporting, about 1.92 million BTC—nearly 10% of supply—were considered “structurally unsafe,” while another 4.12 million BTC (20.6%) were labeled “operationally unsafe.” Glassnode estimated the remaining 69.8% (13.99 million BTC) as unexposed in that framework, broadly aligning with Ark Invest’s earlier March estimate that 65% of supply was safe.

While those figures concern Bitcoin rather than Ethereum, they illustrate the same practical reality that post-quantum migration isn’t just about cryptography. It is also about operational choices—how keys are generated, stored, and used—because those choices determine how quickly protections can be adopted when new threat models emerge.

What to watch next for Ethereum’s post-quantum roadmap

Consigny’s SPHINCS- proposal suggests Ethereum could begin experimenting with post-quantum protections in a deployable way ahead of a larger migration. What remains uncertain is how quickly “SPHINCS-” can move from research to mainstream adoption—particularly as the team evaluates tradeoffs between cost, security properties, and developer ergonomics compared with a more complete future design like leanSPHINCS.

Investors, builders, and wallets should watch for follow-up work on implementation details—especially any evaluations of real onchain costs in production-like environments—and whether client tooling, smart-contract libraries, or account abstraction flows begin incorporating these post-quantum verification options. As quantum timelines remain speculative, the most actionable signal is whether Ethereum can make post-quantum adoption routine without forcing a one-time hard fork.