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zeekayandHanzo Dev af808b25ad validator: node-bound proof of possession, one key per node
The forged certificate that reached crates.io was killed at verification, but a
red review showed the hole had only moved to registration: a key was admitted on
key_validate alone, which proves a point is on the curve and nothing about who
holds its secret, and duplicate keys were merged into one validator carrying many
node ids — so a floor written to require many distinct signers was cleared by one
holder registering one key under several ids.

This is the Go oracle for the standard ruled in luxfi/conformance: it defines the
bytes Rust and C++ reproduce.

validator/pop is the primitive. A registrant signs its own identity followed by
its own key — node(20, ids.NodeID) ‖ pubkey(48, compressed G1), 68 bytes, no
separator — under the proof-of-possession domain BLS_POP_..._POP_, distinct from
the vote's ..._NUL_ so a vote is never a proof and a proof never a vote. The node
is bound because the pubkey-only IETF proof travels with the key: bound to
nothing, it re-registers under any identity. 20 bytes because a Lux validator's
identity IS its NodeID; the 32-byte consensus Id names blocks, not nodes, and has
no canonical inverse, so widening would invent a second name for one node.

validator/registration is the admission rule, written once: encoding, then
possession, then uniqueness, then weight — a pairing on non-points is undefined,
and weight counted before uniqueness is weight counted twice. A set is admitted
whole or refused whole, because a set that silently drops a signer no longer
describes its own weight. FlattenValidatorSet's merge of duplicate keys is retired
here: it was the only thing that made many-nodes-one-key representable, and after
the uniqueness rule that state does not exist to normalize. Order and
PublicKeyBytes still match the upstream flatten exactly, so a proven set and a
flattened-distinct set are the same set.

engine/chain keys the cert store on the DECISION — the signed canonical identity
— not the transport envelope id, which no signature covers: two envelopes of one
decision were two store entries for one finality fact, and a verified cert could
be filed under a block it never attested. Keyed by decision, a cert is found by
anything that finalized that decision, and Put is idempotent per decision.

The pubkey-only P-chain proof (luxfi/node AddValidatorTx) is NOT touched here:
moving it node-bound is a network upgrade, every validator re-proves, and it is
activation-gated as the deliberate last step. Anywhere a validator set that
shares a key across node ids is admitted today, this now refuses it — that is the
intended behaviour, and the coordination point with the P-chain step.

Co-authored-by: Hanzo Dev <[email protected]>
2026-09-01 08:10:24 -07:00
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