An efficient and light client friendly replacement for bloom filters. This EIP proposes a new data structure that adds a moderate amount of consensus data that is optional to store long term, has limited processing and memory requirements and allows searching for log events with 2-3 orders of magnitude less bandwidth than what bloom filters allowed back when they were not rendered useless by over-utilization. It also inherently adapts to changing block utilization and maintains a constantly low average false positive ratio.
Because log_filter_tree uses SSZ merkleization which uses SHA2. I’m not sure whether and when the existing EL structures will be converted to SSZ but for this purpose a binary tree is absolutely the logical choice, Merkle multiproofs are nice and easy with SSZ hash trees, so I think that sticking with the old hexary MPT format would be really impractical. And if we use an existing format with existing tooling then I don’t see a reason to complicate that by not using the hash function it was specified with.