Nicolas Consigny, head of the Kohaku project within the Ethereum Foundation, has announced a technical proposal to add post-quantum protection to Ethereum accounts for just $0.07 per account. Notably, this approach does not require a network-wide hard fork and could provide cost-effective signature verification against future risks from quantum computers.
SPHINCS-based post-quantum solution
The technical paper, released on Saturday via X, presents an optimized adaptation of the SPHINCS+ post-quantum signature standard for Ethereum. Developed by the US National Institute of Standards and Technology (NIST), SPHINCS+ is re-engineered in this context as “SPHINCS-,” offering lower on-chain verification costs without the need for protocol changes or additional precompiles.
Glossary: SPHINCS+ is a hash-based digital signature standard developed in response to the vulnerabilities of classical public-key cryptography to quantum computers. NIST is among the organizations evaluating this standard as part of its post-quantum security initiatives.
Consigny describes SPHINCS- as a transitional solution that could eventually lead to “leanSPHINCS,” a more advanced system able to further cut down verification costs through signature aggregation. The overriding goal is to offer an early and cost-effective answer to the long-term quantum vulnerabilities of Ethereum’s standard Elliptic Curve Digital Signature Algorithm.
The proposal provides Ethereum users with a way to secure their accounts against future quantum computing threats, without requiring a protocol upgrade or incurring high costs, according to the document.
Quantum security debate heats up in crypto
Debates around quantum-related security are intensifying far beyond Ethereum. In April, Project Eleven, a post-quantum security initiative, awarded researcher Giancarlo Lelli for an experiment in which he used a quantum computer to crack a 15-bit elliptic curve key. This test relied on a variant of Shor’s algorithm to derive the private key from its public counterpart.
However, security experts underscore that Bitcoin’s private keys are 256 bits in length—vastly more secure than Lelli’s 15-bit demonstration. Even so, the experiment has reignited debate across the crypto landscape about the theoretical risks posed by quantum computing to current cryptographic infrastructures.
According to Glassnode data, 1.92 million BTC—almost 10% of total supply—is classified as “structurally insecure” in scenarios involving quantum attacks.
Breakdown of risk in Bitcoin
On-chain analytics company Glassnode has reported that about 4.12 million BTC, accounting for 20.6% of the total supply, falls under the “operationally insecure” category due to key and address management practices. By Glassnode’s calculation, the remaining 69.8%—roughly 13.99 million BTC—does not appear directly exposed to quantum threats.
| Category | Amount | Share of total supply |
|---|---|---|
| Structurally insecure | 1.92 million BTC | 10% |
| Operationally insecure | 4.12 million BTC | 20.6% |
| Unexposed supply | 13.99 million BTC | 69.8% |
These figures largely align with a March estimate from Ark Invest, which projected that 65% of Bitcoin’s total supply remains within the safe zone. As the search continues for post-quantum security solutions throughout the crypto ecosystem, Ethereum’s $0.07-per-account proposal represents one of the latest developments in this ongoing discussion.
