feat: native light client state verification #630
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| genesis_root, | ||
| forks, | ||
| execution_state_proof, | ||
| } = serde_cbor::from_slice(&inputs).unwrap(); |
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It would be nice to handle this unwrap() into a new Error value.
| ) | ||
| .is_ok(); | ||
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| apply_update(&mut store, update); |
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That will apply the update even if it was invalid.
Do we want this behavior? Should not we raise up an error in that case (short-circuit)?
| &forks, | ||
| ) | ||
| .is_ok(); | ||
| apply_finality_update(&mut store, &finality_update); |
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Same questions here about applying invalid update.
| let execution_state_branch_nodes: Vec<Node> = execution_state_proof | ||
| .execution_state_branch | ||
| .iter() | ||
| .map(|b| Node::try_from(b.as_ref()).unwrap()) |
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ditto about unwrap to Error
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| is_valid = is_valid | ||
| && is_valid_merkle_branch( | ||
| &Node::try_from(execution_state_proof.execution_state_root.as_ref()).unwrap(), |
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ditto about unwrap to Error.
| let finalized_header_root: [u8; 32] = store | ||
| .finalized_header | ||
| .hash_tree_root() | ||
| .unwrap().as_ref().try_into().unwrap(); |
| finalized_header_root: H256::from(finalized_header_root), | ||
| execution_state_root: H256::from(execution_state_root), | ||
| finalized_slot: store.finalized_header.slot.as_u64(), | ||
| participation: store.current_max_active_participants.try_into().unwrap(), |
| let current_sync_committee_hash: U256 = store | ||
| .current_sync_committee | ||
| .hash_tree_root() | ||
| .unwrap() |
| if let Some(mut next_sync_committee) = store.next_sync_committee { | ||
| let next_period = period + 1; | ||
| let stored_next_sync_committee_hash = SyncCommitteeHashes::<T>::get(next_period); | ||
| let next_sync_committee_hash: [u8; 32] = next_sync_committee |
| @@ -368,7 +383,7 @@ pub mod pallet { | |||
| .expect("Rotate verification key should be valid at genesis."); | |||
| RotateVerificationKey::<T>::set(Some(rotate_verification_key)); | |||
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| SyncCommitteePoseidons::<T>::insert(self.period, self.sync_committee_poseidon); | |||
| SyncCommitteeHashes::<T>::insert(self.period, self.sync_committee_hash); | |||
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The mainnet genesis will be different using this new binary even if we use the same chain spec.
I am not sure about side-effect of that.
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Inside the Vector pallet, instead of verifying a proof of light client logic, we natively implement the logic at a node level. This mirrors SP1 Telepathy's approach. The Rust-based logic built on top of Helios allows for seamless integration with Avail's pallet.
Additionally, this approach dramatically simplifies the operator. Instead of fetching specialized inputs and generating proofs, we simply retrieve inputs for Helios and relay that to the chain.
Modifications
We've optimized storage by directly using the canonical Ethereum consensus state's sync committee hash, eliminating the need for Poseidon hashes.
The updated verification logic is inside the
fulfill_callfunction ofpallets/vector/src/lib.rs.Operator
The new operator is based on SP1 Telepathy's operator. The logic remains the same, with placeholders for reading and writing to Avail using
avail-subxtinstead of a smart contract on Ethereum.For reference, I've created a fork of the SP1 Telepathy operator with added comments highlighting the lines that need to be changed: https://github.com/xavierdmello/avail-telepathy-operator
Testing
We've adapted a few tests into
tests_new.rs, which replaces the currenttests.rs. You can try the new ones by runningcargo test test_fulfillinside of./pallets/vector/. We generated test inputs using SP1 Telepathy (instructions here), which outputs bytes that should be placed inside./pallets/vector/examples