Ethereum developers opened a pull request on Aug. 24 proposing a redesign of the staking deposit contract that would support quantum-resistant validator keys while preserving the option for a future network upgrade to permanently disable BLS deposits.
The draft, submitted as pull request #12235, introduces variable-length fields for public key and credential metadata into the deposit contract, replacing the current fixed BLS12-381 format. The proposal defines a maximum cap of 8,192 bytes for these fields and includes a scheme identifier to tag different key formats.
Three Contract Modes
The design establishes three operational states for the deposit contract: disabled, BLS enabled, and BLS retired. Transitions between modes move forward only and cannot be reversed. Once a BLS retired mode activates, the contract rejects all new BLS deposits permanently. Deposits already submitted before retirement remain eligible for normal processing under current consensus rules.
This one-way switch gives future upgrades a mechanism to sunset the current cryptographic standard without disrupting existing validator stakes.
Post-Quantum Signature Scaling
Ethereum’s post-quantum roadmap pairs a leanXMSS hash-based validator signature scheme with leanVM for efficient aggregation of larger signatures. Post-quantum signatures are approximately 40x larger than current BLS signatures, making the variable-length field design necessary to accommodate future key formats without re-architecting the entire deposit system.
The Ethereum Foundation has targeted 2029 as an approximate planning horizon for quantum threat mitigation, though the organization states no quantum computer threatens its cryptography today.
Draft Status
As of Aug. 26, pull request #12235 remained unmerged and in draft status. The proposal represents an early-stage governance discussion and does not yet reflect consensus among Ethereum developers or a timeline for implementation.
CryptoSlate reported on the proposal’s technical structure and quantum-readiness objectives.
