SCALE: Smart Contract Access Logic for EVM

PROBLEMS

What Problems Are We Solving?

• Compliance is done via UI only. Smart contracts are still ungated.
• Data on-chain is expensive and is slow to publish.

Why Do These Problems Exist?

• Changing data (e.g. growing sanction list), but the blockchain is immutable
• Requires massive data on-chain (e.g. 10,000+ sanction addresses)

SOLUTIONS

Background / Context

• Molecule Protocol: Smart Contract ACL (Access Control List) Middleware
• Use case: Compliance! ETH Global 2020 (KYC), ETH Global 2022 (AML)

What Are The Solutions?

• MP is future-proof: delegated ACL allows add or remove logic anytime
• Publish once, use by all smart contracts, no (huge) duplicate on-chain data

What’s Implemented for the Hackathon?

• Mass data publishing on-chain
• Allow list implementation for subscription payments

(1) MASS DATA PUBLISHING: Layer 1 vs. Layer 2 benchmark

• Ethereum max batch size: 25. 10,000 sanction list => 400 tranctions $$$$$
• Layer 2: size > 500. Deployed on Scroll, Base (Optimism), Polygon, Filecoin

See the screencap for the benchmark of different layer 2 blockchains.

We deployed the sanction lists on different layer 2s--Scroll, Base (OP Stack), Polygon, and Filecoin EVM--and tested each chain's maximum batch transaction size.

(2) SUBSCRIPTION PAYMENT

To take advantage of the lower gas fees on layer 2s, we implemented a modified version of EIP-5643 (Subscription NFTs).

• To allow subscribers to see their subscription, we decide to mint a standard ERC721 to subscriber wallets

• To avoid confusion, each user can only own 1 token, and the tokenID will be irrelevant

• Expiry needs to be tracked

• Sanctioned wallet addresses are not allowed. Gated by using Molecule AML with US and EU sanction lists checked

• The subscription contract is implemented as a Molecule smart contract so it can be composable with other controllers