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Add HistoricalSummariesBlockProof for headers from Capella onwards #291

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kdeme
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@kdeme kdeme commented Apr 19, 2024

PR on top of #287

In draft as this would require a stable Portal beacon network deployed to have access to the historical_summaries.

@@ -179,8 +181,21 @@ HistoricalRootsBlockProof = Container[
slot: Slot
]

BlockHeaderProof = Union[None, AccumulatorProof, HistoricalRootsBlockProof]
# BeaconState historical_summaries proof (for Capella onwards)
HistoricalSummariesProof = Vector[Bytes32, 13] # Proof that BeaconBlockHeader root is part of HistoricalSummaries
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There is possible collusion with the proof for the HistoricalSummaries beacon content type in the beacon network here.

In Trin, I'm using HistoricalSummariesStateProof for the proof of the beacon content.

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Yes I know, I mentioned that name clash here: #287 (comment)

I might reverse the naming because of that.

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I've altered the naming which should avoid the name clash and hopefully also be more clear.

BlockHeaderProof = Union[None, HistoricalHashesAccumulatorProof, HistoricalRootsBlockProof]
# Proof that BeaconBlock root is part of HistoricalRoots and thus canonical
# For Capella and onwards
HistoricalSummariesProof = Vector[Bytes32, 13]
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What would you think about renaming this to something like HistoricalSummariesRootsProof or something similar so it's just 100% clear what it is? In parallel, I wonder if we could rename this beacon chain object to HistoricalSummariesWithStateProof to be 100% clear this is the proof that the summaries are rooted in the current beacon state.

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In Trin we use HistoricalSummariesBlockProof and HistoricalSummariesStateProof. Happy to switch to whatever we decide.

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I think the HistoricalSummariesBlockProof is the container below that holds both the BeaconBlockProof (i.e. the proof that an EL blockhash is part of a beacon block and then what is currently called thethe HistoricalSummariesProof which anchors the Beacon Block root in the HistoricalSummaries. As such, was thinking maybe we can call this second one "HistoricalSummariesRootProof" to reflect that we're anchoring the beacon block root in the particular block_summary_root for the period in which it falls.

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I've altered the naming which should avoid the name clash and hopefully also be more clear.


# Proof for EL BlockHeader for Capella and onwards
HistoricalSummariesBlockProof = Container[
beaconBlockProof: BeaconBlockProof,
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As mentioned on Discord, this type isn't valid for post Capella Beacon Blocks since the proof length is now 12 elements long. I'm assuming we should add a new postCapellaBeaconBlockProof type that's a vector of 12 elements

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Another (preferred) idea is to change the type of BeaconBlockProof to a List[Bytes32, 12]

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I've made the change to List. I'm thinking however about also changing it to 1 same type for also the version that use historical_roots.

history/history-network.md Outdated Show resolved Hide resolved
@kdeme kdeme force-pushed the historical-roots-block-proofs branch from d4d2cd9 to da43ef0 Compare September 17, 2024 11:02
@kdeme kdeme force-pushed the historical-summaries-block-proofs branch from c73d137 to 79fa69d Compare September 18, 2024 09:05
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I would like to make it more clear the Portal Beacon Network isn't required and is one of many options to avoid additional confusion with EL teams for example.

It is easier to prevent confusion then to resolve it later on sorta like preventative care

This chain of two proofs allows for verifying that an EL `BlockHeader` is part of the canonical chain. The only requirement is having access to the beacon chain `historical_summaries`.
The `historical_summaries` is a [`BeaconState` field](https://github.com/ethereum/consensus-specs/blob/dev/specs/capella/beacon-chain.md#beaconstate) that was introduced since the Capella fork. It gets updated every period (8192 slots). The `BlockProofHistoricalSummaries` MUST be used to verify blocks from the Capella fork onwards.

The Portal beacon network [provides access](./beacon-chain/beacon-network.md#historicalsummaries) to an up to date `historical_summaries` object.
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This can lead to confusion that the Portal Beacon Network is the only option to get these.

I think we should either

  • not mention the Portal Beacon Network
  • or mention multiple sources implementations could get this data, for example an EL client wouldn't run the Portal Beacon Network as it already has access to this data from their CL client.

The reason I mention this as it is a question I had to answer multiple times to EL layer teams and is consistently a cause of confusion

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Perhaps I can alter it to:

"The historical_summaries can be taken from the CL BeaconState (Link to beacon API endpoint) or the Portal beacon network also provides access to an up to date historical_summaries object."

And hopefully in a secondary PR I can add a specific API endpoint for it :)

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This sounds like a good solution to me because then it is clear you aren't forced to use Portal beacon but it is 1 of 2 options, which should prevent confusion

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adjusted in ec0200c

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kdeme commented Oct 21, 2024

Again, I'd be fine with moving forward and merging this (after reviews), but with the same remark as here: #287 (comment)

And it also should be clear that we cannot really do the full validation yet for these type of headers as long as we do not have access to historical_summaries.

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:shipit: looks good

@KolbyML KolbyML merged commit f5aed01 into historical-roots-block-proofs Oct 25, 2024
3 checks passed
KolbyML pushed a commit that referenced this pull request Oct 25, 2024
)

* Add HistoricalSummariesBlockProof for headers from Capella onwards

* Add more explanation + charts

* Adjust options for getting historical_summaries based on feedback
KolbyML pushed a commit that referenced this pull request Oct 25, 2024
)

* Add HistoricalSummariesBlockProof for headers from Capella onwards

* Add more explanation + charts

* Adjust options for getting historical_summaries based on feedback
@KolbyML KolbyML deleted the historical-summaries-block-proofs branch October 25, 2024 18:56
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5 participants