Aztec Rollup

Aztec is a privacy focused rollup (or zk-zk-rollup) on Ethereum that enables private transactions and programmable privacy. It is a fully programmable network where applications can access both private and public state.

Aztec - Privacy ZK Rollup

Fits with patterns

Not a substitute for

  • Fully private EVM
  • High througput but public rollups

Architecture

  • Hybrid State Model
    • Private state (UTXO-based) is managed by the wallet on the user's device.
    • Public state (Account-based) is managed by the AVM (Aztec Virtual Machine) on nodes.
  • Smart contracts are written in Noir using the Aztec.nr framework.
  • Proof system: Honk (UltraHonk) and UltraPlonk. Honk allows for fast recursion and removes the need for a trusted setup.
  • DA model: Rollup posts data to Ethereum L1 using EIP-4844 Blobs.
  • Settlement: Decentralized sequencers; L2 validity proofs are verified on Ethereum L1.

Privacy domains

  • Private transfers: Optional shielding of token amounts, counterparties from the public chain.
  • Selective disclosure: Users can export viewing keys for auditors/regulators.
  • Programmable privacy: Circuits allow private execution of DeFi-like logic (DEX, lending) within Aztec.

Enterprise demand and use cases

  • Financial institutions: private stablecoin transfers and settlement.
  • Asset managers: confidential DeFi strategies and portfolio movements.
  • Corporate treasuries: cross-border payments with regulatory audit but hidden competitive data.

Technical details

  • zkSNARKs: Plonkish proving system with efficient verifier contracts.
  • UTXO note commitments with nullifiers to prevent double spends.
  • Wallets discover notes via a note tagging mechanism to avoid having to trial-decrypt all note history.
  • L1/L2 communication relies on "Portals". These are pairs of contracts (one on Ethereum L1, one on Aztec L2) that pass messages asynchronously via the rollup contract, enabling token bridges and cross-chain governance without trusted 3rd parties.
  • Native account abstraction at the protocol level; all accounts are smart contracts.
  • Decentralized block building. Validators stake AZTEC tokens to participate in block production. A proposer is chosen per L2 slot at random through RANDAO, and a committee must attest to the validity of the blocks it produces.
  • An escape hatch mechanism allows users to exit the chain even if the validator set censors them.

Strengths

  • Strong privacy guarantees for: any private data, private function execution, private smart contract code, privacy over who executed the functions.
  • Programmable privacy smart contract execution extend beyond simple shielded transfers.
  • Mature research team with open-source infrastructure and audits.

Risks and open questions

  • State Storage, user wallets must store their entire private state to be able to access it, rather than just querying a node.
  • Client-Side Proving, private execution requires local execution and proof generation (via PXE), demanding compute resources for end users (eg an AMM swap takes 8s to prove in an Android device).
  • Compliance vs. Permissionlessness, While "Selective Disclosure" exists, it is unclear if regulators will accept retroactive auditing over proactive censorship (e.g., OFAC lists at the sequencer level).
  • Performances, this system requires a lot of engineering at the cost of a lower throughput, raising the question of use cases that it could tackle.

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