[Interop] Lock Commitment

[Therecanbeonlyone1969]

We need to finalize a decision on Lock Commitment for the BPI State Object the Interop Worksteps are working on:

Suggestion:

Use Sparse Merkle Tree (SMT) since this allows proof-of-non-membership of the hash of the BPI State Object.

That then needs a separate Smart Contract to

• store the Merkle Proof & verify it
• verification function that proof is correct (proof has to be verified onchain only once, and then we just need a mapping that says that the proof for this commitment was verified
• Store function only for owning BPI
• Verification function open to public

[Therecanbeonlyone1969]

Interop WG Meeting 7/21 agrees to use SMTs for lock commitments. @Therecanbeonlyone1969 to write the contract and PR it.