Skip to main content

Core Concepts

Zero-knowledge proofs in Privacy Pools​

Privacy Pools uses zero-knowledge proofs to demonstrate valid statements about private information without revealing that information. The protocol employs three proof types:

  • Commitment Proofs: Verify the ownership of a commitment
  • Withdrawal Proofs: Verify ownership and inclusion in state of a commitment
  • Merkle Proofs: Demonstrate membership in a tree without revealing position

Commitments and nullifiers​

A PrivacyPool commitment is a note for some value deposited in a Pool composed of:

  • value: The amount being committed
  • label: A unique identifier derived from scope and nonce
  • nullifier: A secret that prevents double-spending
  • secret: A value that helps hide the nullifier

The protocol uses:

  • Commitment Hash: PoseidonHash(value, label, precommitmentHash)
  • Precommitment Hash: PoseidonHash(nullifier, secret)
  • Nullifier Hash: PoseidonHash(nullifier)

These values enable secure state transitions while maintaining privacy.

Basic operations​

  • Deposit
    • User generates commitment components
    • Deposits funds and submits commitment to pool
    • Commitment is added to the state tree
  • Withdrawal
    • User proves ownership of an existing commitment
    • Creates new commitment for remaining funds
    • Marks previous commitment as spent
    • Receives withdrawn assets
  • Ragequit
    • Original depositor proves ownership of a commitment
    • Recovers full remaining deposit value
    • Marks commitment as spent