A new draft proposal could give Ethereum validators a path to adopt quantum-resistant keys while eventually phasing out the cryptographic format currently used across the network.
A group of Ethereum researchers is proposing changes to the deposit contract that allows users to become validators, aiming to prepare the blockchain for potential attacks enabled by future quantum computers.
The proposal targets Ethereum’s deposit contract, the gateway through which users lock ETH to become validators. These network participants verify transactions and help maintain consensus. Under the proposed changes, the contract would gain an option to eventually stop accepting the signature format used today.
Ethereum’s BLS Keys Pose a Quantum Risk
Ethereum’s current deposit system creates a major hurdle for adopting new cryptography because it hard-codes the size of BLS key pairs. Even if developers selected a quantum-resistant signature scheme, the network could not support it through the existing deposit contract without modifying the system first.
About 42.4 million ETH is currently staked on Ethereum, worth approximately $104 billion at current prices. Those assets are protected by validator keys based on the BLS format that the proposal would ultimately seek to replace.
The proposal remains an early-stage draft and has not yet received a final EIP number. It is currently listed under a placeholder identifier, while a repository maintainer has suggested EIP-8394 as a possible designation.
The plan would also retire the original deposit-processing mechanism introduced when Ethereum staking launched in 2022. Deposits would instead be handled through the newer system already used for withdrawals and validator updates.
Proposed Multi-Key System Explained
Ethereum validators currently use BLS signatures to participate in network consensus. BLS technology allows large numbers of signatures to be aggregated into a single signature, reducing the cost and complexity of securing Ethereum’s consensus layer.
The underlying cryptography relies on elliptic-curve mathematics, which could potentially be broken by a sufficiently capable quantum computer using Shor’s algorithm. An attacker who successfully exploited the weakness could potentially forge validator signatures.
The existing deposit contract accepts only BLS keys because their dimensions are fixed in the code. The proposed redesign would support different key sizes, with every deposit carrying a tag identifying its cryptographic scheme. Existing BLS deposits would use tag zero, while additional tags could later be assigned to quantum-resistant alternatives.
Under the proposed rollout, BLS deposits could continue initially while alternative signature systems are added. Ethereum developers could later activate a mechanism that permanently blocks new BLS deposits. Validators already using BLS keys would continue operating, but newly joining validators would have to use another supported cryptographic scheme.
A separate protocol upgrade would then be required to teach Ethereum’s validator system how to verify signatures generated by the new cryptographic methods.
Ethereum Builds a Broader Quantum-Resistance Plan
The proposed validator changes are part of a larger effort to prepare Ethereum for quantum computing. Another piece of the transition is EIP-8141, or the Frame Transactions proposal, which is being considered for the Hegotá upgrade expected later this year.
EIP-8141 would allow ordinary Ethereum accounts to switch the cryptographic technology used to authorize transactions without requiring users to transfer their assets to new addresses.
The push has gained urgency following Google Quantum AI research published in March that outlined five possible quantum attack paths targeting Ethereum. The research estimated that more than $100 billion in assets could face potential exposure across wallets, staking, smart contracts and layer-2 networks.
The Ethereum Foundation is now targeting approximately 2029 for implementing the core protocol changes needed to make the network resistant to quantum-based attacks.
