A group of Ethereum researchers proposed rebuilding the contract that allows participants to become validators to help secure the blockchain from potential quantum-computing enabled attacks.
The proposal targets the deposit contract, or entry point through which users lock up ether to qualify as validators, the operators who verify transactions and keep the blockchain running. It seeks to add a switch to prevent the network accepting the signature format it currently relies on.
The current format is one of the obstacles to implementing a broader rollout. Because it hard-codes the size of the specialized cryptographic key pairs known as BLS keys, Ethereum could not accept a quantum-resistant signature even if developers agreed on one tomorrow.
Roughly 42.4 million ETH is staked on Ethereum as of Wednesday, worth about $104 billion at current prices, all of it secured by validator keys using the format the draft would eventually retire.
The proposal is an early draft awaiting review, currently filed under a placeholder number, with one of the repository's maintainers suggesting it be numbered EIP-8394.
The proposal also retires the old deposit-processing system Ethereum has used since staking was introduced in 2022 and transfers deposits onto the newer framework already handling withdrawals and validator changes.
Validators currently sign transactions with BLS, a system whose main advantage is that hundreds of thousands of signatures can be squashed into one, which is what keeps Ethereum's consensus affordable.
The technology, however, is built on the elliptic curve maths that a quantum computer running Shor's algorithm could unpick, letting an attacker forge a validator's signature.
Read more: Ethereum Foundation prepares for quantum threat with new cryptography roadmap
Currently, the contract accepts only BLS keys because the exact size is hard-coded. The draft proposal allows for different key sizes, with each deposit tagged to show which cryptographic system it uses. BLS gets tag zero, leaving later tags open for whatever comes next.
If approved, the proposal would deploy with BLS deposits operational and other schemes able to register alongside them. A later decision could disable new BLS deposits permanently. In that case, validators already staking with BLS keys would not vanish, but new validators would be unable to join with one.
As such, Ethereum would eventually also need a separate change telling validators how to check whatever new signatures arrive.
This is the validator half of a migration whose other half is already in play. EIP-8141, the Frame Transactions proposal under consideration for the Hegotá upgrade due later this year, would allow ordinary Ethereum accounts to change the cryptography approving their transactions without moving to a new address.
The urgency traces to Google Quantum AI research in March, which mapped five quantum attack paths against Ethereum and put more than $100 billion of assets at potential risk across wallets, staking, smart contracts and layer-2 systems, as CoinDesk reported at the time. The Ethereum Foundation, the organization that supports the blockchain’s development, is now working to a target of roughly 2029 for the core protocol changes.
Read more: Google warns five quantum attack paths could put $100 billion on Ethereum at risk