fix: drop amnesia attacks in consumer misbehaviour handling #1388
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| // we can't identify the byzantine validators. | ||
| // | ||
| // Note that we cannot differentiate which of the headers is trusted or malicious, | ||
| if !headersStateTransitionsAreConflicting(*lightBlock1.Header, *lightBlock2.Header) && lightBlock1.Commit.Round != lightBlock2.Commit.Round { |
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It's not clear to me why those header fields (i.e., ValidatorsHash, NextValidatorsHash etc.) must be the same?
I'm not sure what I'm missing but my understanding is that for this to be misbehaviour the blockIDs have to be different (e.g., see here) and blockID is a hash that incorporates among others the above fields (?)
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These fields must be the same because, in all amnesia scenarios, it's assumed that correct validators validate both headers.
The BlockID hash contains other fields that are only related to the current block e.g. the time or the proposer.
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Deleted my previous comment. After the offline discussion we had yesterday this makes sense and the above code checks what CometBFT already checks in GetByzantineValidators.
Thanks @sainoe !
Just for posterity: If we have 2 headers at the same height H with h1.AppHash != h2.AppHash then this is a lunatic attack because AppHash is computed as the "state after txs from the previous block" H - 1. Only a "lunatic" validator would have 2 different views of the AppHash when applying the transactions of a previous block. The same is the case for all the fields that are based on the previous block which are the ones checked against in headersStateTransitionsAreConflicting. In case of a lunatic attack we can still slash.
Description
Closes: #1387
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