A draft Ethereum proposal would let validators begin depositing with quantum-resistant cryptographic keys and eventually shut down the existing key format used by the network.
Ethereum researchers have proposed redesigning the deposit contract that enables users to become validators, with the goal of strengthening the blockchain against potential attacks powered by quantum computers.
The proposal focuses on Ethereum’s deposit contract, which serves as the entry point for users who lock up ETH to become validators. These validators confirm transactions and help maintain the network. The draft would introduce a mechanism that could eventually prevent the network from accepting the signature format currently used for validator deposits.
Ethereum’s Current Validator Keys Face a Quantum Challenge
The existing format presents a major limitation to a broader transition to quantum-resistant cryptography. Because the deposit contract permanently specifies the size of BLS cryptographic key pairs, Ethereum would be unable to accept a new quantum-resistant signature scheme without first changing the underlying system.
Around 42.4 million ETH is currently staked on Ethereum, representing roughly $104 billion at current prices. All of those assets are secured by validator keys using the BLS-based format that the proposal could eventually phase out.
The proposal is still in its early stages and has been submitted for review under a temporary number. A repository maintainer has suggested assigning it the formal designation EIP-8394.
The draft would also replace Ethereum’s original deposit-processing system, which has been used since staking launched in 2022. Deposits would instead move to the newer framework already responsible for processing withdrawals and validator-related changes.
How the Proposed System Would Work
Ethereum validators currently use BLS signatures when participating in network consensus. One of the main benefits of BLS is its ability to combine large numbers of signatures into a single signature, helping keep Ethereum’s consensus system efficient and affordable.
The cryptographic technology is based on elliptic-curve mathematics, however, which could potentially be compromised by a sufficiently powerful quantum computer running Shor’s algorithm. Such an attack could allow an attacker to create fraudulent validator signatures.
At present, the deposit contract accepts only BLS keys because their size is fixed in the contract. The proposed system would remove that restriction by supporting multiple key sizes and attaching a tag to each deposit identifying the cryptographic scheme being used. BLS deposits would receive tag zero, while future tags could represent alternative signature systems.
If adopted, the new contract could initially continue accepting BLS deposits while allowing other cryptographic schemes to be registered alongside them. Ethereum developers could later decide to permanently stop accepting new BLS deposits. Existing validators using BLS keys would remain active, but new validators would no longer be able to join using that format.
Ethereum would then need another protocol change to establish how validators should verify the new types of signatures.
Ethereum’s Broader Quantum Migration
The validator-focused proposal represents one part of a wider transition toward quantum-resistant cryptography. Another component is already being considered through EIP-8141, known as the Frame Transactions proposal, which is being evaluated for the Hegotá upgrade expected later this year.
That proposal would allow regular Ethereum accounts to change the cryptographic method used to authorize transactions without requiring users to move their assets to a different address.
Concerns about quantum security intensified after Google Quantum AI research published in March identified five potential attack routes against Ethereum. The research suggested that more than $100 billion in assets could eventually be exposed across wallets, staking systems, smart contracts and layer-2 networks.
The Ethereum Foundation, which supports development of the blockchain, has been working toward roughly 2029 as a target for implementing the core protocol changes needed to address the quantum-computing threat.
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