fix(dkg): verify deal signature before marking a dealer dealt#856
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markDealersDealt recorded DealtDealers for a dealer based only on a bounds check of deal.Index. Deals come from vote extensions and are unauthenticated, so a Byzantine validator could broadcast a forged deal carrying any dealer's index and shield a genuinely-missing dealer from invalidateMissingDealers. Verify each deal's Schnorr signature against the dealer's registered dkgPubKey before recording it. The signed message matches kyber dkg.Deal.MarshalBinary (little-endian uint32 Index followed by the EncryptedDeal cipher); invalid signatures are skipped. Verification is deterministic, so all nodes agree in the FinalizeBlock path.
0xHansLee
requested review from
jdubpark,
lucas2brh and
stevemilk
as code owners
July 21, 2026 05:19
stevemilk
approved these changes
Jul 21, 2026
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Problem
markDealersDealtrecorded a dealer as having dealt based only on a bounds check ofdeal.Index. A forged deal carrying another dealer's index would mark that dealer dealt, shielding a genuinely-missing dealer frominvalidateMissingDealers.Fix
Verify each deal's Schnorr signature against the dealer's registered
DkgPubKeybefore recording it. The signed message matches kyberDeal.MarshalBinary(little-endianuint32index followed by the cipher). Verification is deterministic pure compute over consensus-shared state (block deals + on-chain pubkeys), runs on all nodes under the existingisV190Roundgate, and adds no new KV reads — soGasUsedand the resultingDealtDealersset stay identical across nodes.Tests
TestMarkDealersDealt_VerifiesSignature(valid / forged-key / unsigned)issue: none