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Smart Contracts Layer

Contract architecture overview​

The Privacy Pools protocol is built on three core contracts:

  1. Entrypoint
    • Central access point for deposits
    • Manages pool registry and ASP root updates
    • Handles fee collection and relay operations
    • Controls protocol-wide settings
  2. Privacy Pools
    • PrivacyPoolSimple: Handles native asset (ETH)
    • PrivacyPoolComplex: Handles ERC20 tokens
    • Both inherit from base PrivacyPool and State contracts
  3. Verifiers
    • CommitmentVerifier: Validates ragequit proofs
    • WithdrawalVerifier: Validates withdrawal proofs
    • Both implement Groth16 verification

Component interaction​

  • User operations flow through the Entrypoint:
    • Deposits route funds to appropriate pools
    • Withdrawals can be direct to the Pool or relayed through the Entrypoint
    • Fees are deducted and distributed
  • Privacy Pools handle:
    • Asset custody and proof verification
    • State tree updates
    • Nullifier tracking
    • Ragequit operations
  • The ASP layer interacts through:
    • Root updates via authorized postman
    • Label verification during withdrawals

State management basics​

Each Privacy Pools maintains:

  1. Tree State
    • Lean Incremental Merkle Tree (LeanIMT) for commitments
    • Dynamic depth that grows with insertions
    • Cached roots for historical validation
  2. Nullifier Registry
    • Tracks spent nullifiers to prevent double-spending
  3. Deposit Records
    • Maps labels to original depositor addresses
    • Tracks deposit amounts
    • Enables direct recovery through ragequit