New EIP! EIP-8450: Post-Quantum Validator Key Registry (leanXMSS + VRF root) 🔗 github.com/ethereum/EIPs/pul… Highlights: - Each validator registers two post-quantum commitments in beacon state: a leanXMSS public key for future signing and a 32-byte VRF-tree root to commit to non-grindable random outputs. - Registration is a new consensus-layer operation (no execution-layer request path): it includes a proof-of-possession signed with leanXMSS at leaf index 0 and is authorized by a BLS signature from the validator’s current pubkey. - To prevent replay and throttle changes, each validator has a stored last-change epoch; the registration includes the previous_change_epoch and key changes are rate-limited by MIN_PQ_KEY_CHANGE_DELAY (default 256 epochs; smaller in minimal preset). - Uniqueness is enforced for the leanXMSS key across validators (so validators can’t share/copy signing keys), but VRF roots are allowed to collide (two validators may commit to identical VRF trees). - The registry is ‘dormant’ in this fork (duties still use BLS); its purpose is readiness measurement and early verification/testing of post-quantum primitives defined externally in EIP-CRYPTO. ELI5: Ethereum validators currently use BLS signatures, which quantum computers could break. This EIP adds a new “phonebook” in the beacon chain state where each validator can pre-register post-quantum cryptographic material ahead of a later upgrade. Each validator stores (1) a hash-based leanXMSS public key for future signatures, and (2) a Merkle-root commitment to a huge VRF tree that pre-fixes one random-looking output per index so validators can’t ‘game’ randomness-based selections later. Validators prove they really control the leanXMSS key (proof of possession) and authorize updates with their existing BLS key; the new keys are recorded now but not used for duties until a future fork.