Ethereum developers have submitted a draft proposal to replace the network’s validator deposit contract, marking the first concrete step toward protecting the blockchain’s staking layer from quantum computing attacks.
What the Proposal Changes
The draft Ethereum Improvement Proposal, filed to the EIP repository on Monday, targets a fundamental limitation baked into the existing deposit contract: it hardcodes the dimensions of the BLS12-381 signature scheme, fixing public keys at 48 bytes and signature metadata at 96 bytes. Post-quantum cryptographic schemes require far more space, and the current contract cannot accommodate them.
The replacement contract would accept validator keys and credential metadata of up to 8,192 bytes each. Every deposit would be required to declare a ‘credential scheme’ identifier. Scheme zero maps to the existing BLS signatures. No other schemes are defined in this proposal, leaving a future EIP to specify what a post-quantum validator key actually looks like.
That sequencing is worth stating plainly. What has been proposed is the container, not the contents. The contract would be able to hold a post-quantum key, and which post-quantum key it holds remains an open question for a separate proposal.
The contract operates in three states: disabled, BLS enabled, and BLS retired. Once a system call pushes the contract into retirement mode, the authors write, no subsequent call can restore BLS onboarding. That retirement is irreversible by design.
Activating the new contract would require a coordinated hard fork across both Ethereum’s execution and consensus layers.
Not a ‘Simple Upgrade’
The pull request carries a draft label and is pending review from the EIP editors. The contract address, deployment bytecode, and both activation timestamps remain undecided.
Thomas Coratger, one of three authors on the proposal, published a separate thread the same day outlining how unsettled the underlying cryptography remains. Summarising a lecture by Stanford cryptographer Dan Boneh, Coratger wrote that Bitcoin and Ethereum are both ‘heavily leaning’ toward hash-based signatures, which rest only on security assumptions the networks already rely upon.
The stateless hash-based signature variants standardised by NIST reach roughly 8 kilobytes each, which is precisely why the new contract sets 8,192 bytes as its ceiling. The more compact stateful variants carry a counter that permanently exposes the private key if a signer ever reuses it. ‘Post-quantum cryptography isn’t a simple upgrade,’ Coratger wrote.
Why the Timeline Matters
The Ethereum Foundation assembled a dedicated post-quantum working group in 2025 to plan the network’s migration. A May 2026 report from quantum security firm Project Eleven placed the odds of a quantum machine capable of breaking elliptic curve signatures at better than even by 2033, with 2030 identified as a plausible earlier date.
The exposure is already significant. More than 65% of all ETH sits in addresses whose public keys are already visible on-chain, according to the Project Eleven analysis, meaning those funds could theoretically be targeted by a sufficiently powerful quantum computer.
Ethereum’s staking layer holds more than $100 billion in value, making the deposit contract one of the most consequential pieces of infrastructure the network runs.
