engine: specify bit ordering for the 16-byte custody and cell bitarrays - #856
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edg-l wants to merge 1 commit into
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engine: specify bit ordering for the 16-byte custody and cell bitarrays#856edg-l wants to merge 1 commit into
edg-l wants to merge 1 commit into
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custodyColumns and indices_bitarray are both 16-byte bitarrays with no stated bit-to-byte mapping. Reference the SSZ BitVector serialization, which is what go-ethereum already implements.
edg-l
marked this pull request as ready for review
July 31, 2026 08:25
mkalinin
approved these changes
Aug 4, 2026
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engine_forkchoiceUpdatedV4'scustodyColumnsandengine_getBlobsV4'sindices_bitarrayare both 16-byte bitarrays with no stated bit-to-byte mapping. The failure is silent: a reversed order still decodes to a well-formed 128-bit set, so the EL adopts the wrong custody set, or returns cells the CL did not ask for, instead of returning an error.The ordering specified is the SSZ serialization of
BitVector[CELLS_PER_EXT_BLOB](consensus specs),array[i // 8] |= value[i] << (i % 8). The custody set is SSZ-native, so this introduces no new convention. It matches go-ethereum, wherecore/types/custody_bitmap.gosetsresult[i/8] |= 1 << (i % 8)and marshals the 16 bytes as plain hex. ethrex implements the same ordering.Documentation only: the fields stay
DATA, 16 bytes, nothing on the wire changes, and no OpenRPC change is needed since both are already typedbytes16. Confirmation from other client teams would be welcome, and if any client packs the bits the other way round that is worth surfacing before this merges.EIP-8070 carries the same definitions and has the same gap: ethereum/EIPs#12054, wording kept identical so the documents cannot drift.