EIP7549 compute_on_chain_aggregate

[eserilev]

Issue Addressed

#5605

Proposed Changes

Electra Attestations that share equal AttestationData will now be aggregated before being submitted on chain. See spec for implementation details

Additional Info

Running through several test cases, I found situations where we had duplicate attestations being included in a beacon block. Aggregating duplicate attestations will cause InvalidSignature errors, so I added an additional check to skip duplicate attestations during the aggregation process.

[michaelsproul]

I think this needs to consider the committee_bits:

lighthouse/consensus/types/src/attestation.rs

Lines 225 to 230 in 3a41e13

	/// Are the aggregation bitfields of these attestations disjoint?
	pub fn signers_disjoint_from(&self, other: &Self) -> bool {
	self.aggregation_bits
	.intersection(&other.aggregation_bits)
	.is_zero()
	}

I think the logic for disjointness should be:

• committee_bits are disjoint (fast check), OR
• committee_bits overlap, but at all overlapping committees, the aggregation_bits for those committees are disjoint

Similarly this aggregate function should build the new list of committee bits and append all of the aggregation_bits in order:

lighthouse/consensus/types/src/attestation.rs

Lines 247 to 252 in cd0f08b

	pub fn aggregate(&mut self, other: &Self) {
	debug_assert_eq!(self.data, other.data);
	debug_assert!(self.signers_disjoint_from(other));
	self.aggregation_bits = self.aggregation_bits.union(&other.aggregation_bits);
	self.signature.add_assign_aggregate(&other.signature);
	}