feat(validator): refuse to sign a slot a key already signed - #1204
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feat(validator): refuse to sign a slot a key already signed#1204adust09 wants to merge 1 commit into
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The signature scheme is a stateful one-time signature indexed by slot, and `sign` states that a key must never sign two different messages for the same slot without enforcing it. The only thing upholding that was `_attested_slots`, an in-memory set pruned after four slots, with no per-slot guard at all on the proposal path. A crash-restart inside a slot, a backward clock step, or a restore from backup therefore re-ran the duty against a possibly different head and signed a second message under the same one-time key, which opens two positions in the same hash chains and lets a third signature be forged. Record the highest slot each validator key has signed and check it at the signing boundary. The record lives in the node database, so it survives a restart; without a database it stays process-local and `run` warns that the protection is not durable. Attestation and proposal keys are tracked separately, so signing both in one slot stays legal. The claim commits before the signature so an interruption in between forfeits the duty, not the key. `_attested_slots` stays as the duty loop's dedup optimization; the new record is the safety guarantee. Signing records are never pruned: dropping a row re-opens the key it protects. Closes leanEthereum#1203
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Closes #1203.
sign()requires that a key never sign two different messages for one slot, but only an in-memory set upheld it — and the proposal path had no per-slot guard at all. A crash-restart, a backward clock step, or a restore re-ran the duty against a possibly different head and signed twice under the same one-time key.Records the highest slot each key has signed and refuses
slot <= last_signed_slotat the signing boundary.signing_recordstable keyed by(validator_index, key_role), never pruned.run()warns._attested_slotsstays as the duty loop's dedup.Concurrent nodes sharing a key keep separate records, so exclusive key-store access remains an operational requirement.
17 new tests, including a restart scenario: sign slot 1, reopen the database, replacement service refused. 2961 passed, coverage 91.79%.