Aztec: The Private World Computer for Ethereum Privacy

Key Concepts

Aztec Network: A ZK rollup designed to bring programmable privacy to Ethereum.
ZK Rollup: A Layer 2 scaling solution that uses zero-knowledge proofs to bundle transactions off-chain and submit a single proof to the mainnet.
Programmable Privacy: The ability to build and execute complex smart contracts and DeFi applications with inherent privacy features.
Private World Computer: Aztec's vision for an Ethereum-like environment where all transactions and interactions can be private by default.
ZK Passport: A technology that uses zero-knowledge proofs to verify government-issued e-passports on-chain without revealing personal data.
Holistic Identity: A bottom-up, decentralized approach to identity on Aztec, where applications issue ZK-attested credentials, allowing for meta-credentials without centralized control.
Noir Programming Language: Aztec's developer-friendly language for writing zero-knowledge applications, directly compiling to ZK circuits.
Private Intents: A mechanism allowing users to route transactions through Aztec to interact privately with existing DeFi liquidity and smart contracts on Ethereum L1 and other L2s.
Decentralized Sequencing: A system where anyone can permissionlessly stake Aztec tokens to become a sequencer and validator, producing and validating blocks.
Decentralized Proving: A permissionless system where anyone can act as a prover for the network's ZK proofs.
Continuous Clearing Auction: A Uniswap-partnered token distribution model designed for fair access and price discovery for the Aztec token (AZTEC).
EIP-1559 Fee Model: A transaction fee mechanism similar to Ethereum's, where a base fee adjusts with network congestion and is burned.
AIC Stack (Application-Specific Rollup Stack): Aztec's future scaling solution for very high-throughput applications, allowing L3s to settle onto Aztec.
Preemptive Compliance: A system where transactions are only executed if all parties are proven to be compliant before the transaction occurs, using ZK proofs.
Undercollateralized Lending: Financial services that provide loans based on a user's verified identity and creditworthiness (e.g., income, outgoings) rather than over-collateralization.
Dark Pools / OTC Desks: Private decentralized exchange models that hide trade participants or total flow, enabled by Aztec's privacy.

Aztec's Core Mission: A Private Ethereum

The Aztec project, led by Zach and Joe, aims to bring programmable privacy to Ethereum, creating a "private Layer 2" that extends Ethereum's decentralization with private transactions for all of DeFi. After five years of development, the Aztec network is live, producing private, Ethereum-secured blocks, with an alpha mainnet launch anticipated in early 2024. This initiative is positioned as potentially the most "cipher punk" project since 2016, challenging the narrative that the world doesn't care about decentralization and privacy. The core belief is that while the world may not care about privacy, it needs it more than ever.

The Current State of Privacy on Ethereum

Zach highlights that despite increased awareness, the quality of privacy on Ethereum hasn't significantly changed in five years. Ethereum remains a completely transparent network, where all transactions reveal sender, recipient, smart contracts called, programs used, and amounts. This transparency severely restricts competitive and professional use cases, as demonstrated by attacks against portfolio hedging on platforms like Hyperliquid. While some privacy protocols like Railgun exist, and Tornado Cash is no longer sanctioned, the fundamental challenge has been adding programmability to privacy. True advanced privacy requires understanding "who somebody is" to distinguish between good and bad actors, a difficult problem in a permissionless, decentralized network without relying on centralized third parties.

ZK Passport: Revolutionizing Identity and Combating Deepfakes

Joe introduces ZK Passport as a significant breakthrough in identity, leveraging advancements in ZK technology. Unlike previous methods relying on third-party credentials, ZK Passport allows for on-chain verification of government-issued e-passports (e.g., UK, US) using zero-knowledge proofs. Users can selectively disclose information (e.g., age, non-sanctioned status) to a smart contract without revealing their full identity.

The technology utilizes the NFC chip embedded in modern e-passports, which contains data digitally signed by the issuing nation-state. This chip is counterfeit and tamper-resistant, relying on a "tree of trust" where a nation-state's private key signs each chip. ZK Passport reads this chip via an NFC scanner (e.g., a smartphone), decrypts the information, and creates a ZK proof of its validity. Ethereum effectively becomes an "e-gate" for transactions.

This approach directly addresses the emerging threat of AI deepfakes, which are poised to break traditional AML/KYC methods relying on ID pictures and liveness checks. ZK Passport not only verifies the NFC chip but also performs a liveness check using the phone's secure enclave, matching the user's live face to the passport photo. Crucially, this sensitive information never leaves the user's phone; only a digital signature confirming the check is broadcast.

ZK Passport is a project funded within Aztec's ecosystem, and its proofs can be verified off-chain, in Ethereum smart contracts, or natively within Aztec transactions. It has already been used in Aztec's ongoing token sale, where Swiss regulators accepted a ZK proof of non-sanctioned status as a valid compliance check, offering a privacy-preserving alternative to traditional KYC.

Holistic Identity and Programmable Privacy on Aztec

Zach explains that while ZK Passport is powerful, it won't be mandated for everyday Aztec interactions due to convenience. Instead, Aztec promotes a "holistic identity" model: a bottom-up, decentralized approach. Application developers can easily program specific identity checks into their applications using Noir, Aztec's programming language. These checks can be simple (e.g., "user has a Twitter account with >100 followers" via ZK email) and result in the issuance of on-chain credentials (NFTs or tokens). Over time, these individual credentials can be combined to create meta-credentials, providing more concrete information about an individual.

The key benefits are:

ZK-powered: All data remains on the user's device, with only encrypted proofs on-chain.
Decentralized: Identity is attested by hundreds of different on-chain sources and counterparties, not a single, controlling identity provider.

This approach addresses why similar identity solutions haven't taken off on Ethereum: earlier versions required intermediaries or struggled with Web2 cryptography in ZK. Aztec's design, where every transaction is a zero-knowledge proof, allows for seamless, succinct, and cheap verification of diverse data sources within a single transaction. Furthermore, Ethereum's lack of default privacy leads to an "explosion of complexity" for developers trying to build private, composable systems. Aztec's private-by-default blockchain and Noir language enable private smart contracts to call each other effortlessly, fostering a true network effect for composable private systems.

Aztec's Architecture: The Private World Computer and Private Intents

Aztec's mission remains to bring Ethereum's Turing-complete programmability, including all of DeFi, into a private context. This was the core challenge that took years to solve, specifically preserving composability between smart contracts.

The new Aztec chain builds upon the lessons from its predecessor, Aztec Connect. While Aztec Connect offered Zcash-style private transactions for ERC20s with L1 DeFi interaction, the new chain integrates this functionality into every smart contract. This means users can bridge funds from any Ethereum smart contract or L2 smart contract and interact with existing DeFi pools (e.g., on Base, Arbitrum, Optimism) without needing to rebuild protocols like Uniswap or Aave natively on Aztec.

This is achieved through "private intents." A user with private funds on Aztec can send an intent (e.g., "swap 10 ETH for USDC on Base") to the Aztec L2. A relayer picks up this intent, fills it on the destination chain, and returns the funds (either to Aztec, a new account abstraction account on Base, or even L1). The public only sees that "someone on Aztec wants to swap 10 ETH for USDC on Base," preserving the user's privacy.

While bridging still occurs, the goal is to streamline the user experience, potentially allowing L1 wallets to offer a seamless "make this transaction private" button. Aztec is envisioned as a "pass-through chain," where a percentage of L2 transactions route through it for privacy. This model is positive-sum, unlike many L2s that are parasitic to their L1s. Aztec gains fees from processing information (identity checks, private DeFi intents), while other L1s/L2s gain added value from connecting to a privacy layer.

Transaction fees on Aztec are expected to be nominal (2-5 cents) and fixed, following an EIP-1559-like model. There will be some latency (one block on Aztec, one on destination), but faster block times aim for a smooth user experience.

Decentralization Strategy and Launch Phases

Zach and Joe assert that Aztec "largely solves" privacy on Ethereum, but the challenge now lies in execution and adoption. They compare Aztec's current stage to "where Ethereum was in 2015, but for privacy."

The Aztec Ignition chain launched in a decentralized manner at Dev Connect, with the community running all nodes. It's currently in a "beacon chain type" phase, where users can stake Aztec tokens (200,000 AZTEC required) to become sequencers and validators. These roles are permissionless, and there are already ~600 validators on mainnet. The gas limit is currently set to zero, meaning transactions are not yet enabled. After audits are complete (early-to-mid February 2024), a governance vote by sequencers will enable transactions.

Aztec aims to be the first fully decentralized Layer 2, encompassing:

Decentralized Sequencing: Anyone can permissionlessly participate.
Decentralized Proving: Provers are also fully permissionless.
Decentralized Governance and Ownership: The ongoing token sale aims to distribute network control to the community.

This "one-shot" decentralization, leapfrogging other L2s' progressive decentralization, is possible due to aligned incentives: as a privacy network, Aztec must be neutral and permissionless. While acknowledging "fierce technical risks" (bugs), Aztec is implementing a phased rollout with "health warnings" for early users, a generous bug bounty, and clear security milestones (e.g., 3 months without critical bugs, 99% uptime) before being deemed "completely safe." Users engaging in private intents are only at risk during the brief "in-flight" period of asset movement, not by storing value on the early network. Furthermore, fully private smart contracts have a reduced attack surface as funds are hidden.

Technical Deep Dive: Throughput, VM, and Scaling

Aztec is a ZK rollup where every user transaction is a ZK proof. Smart contracts can have both private and public components, each with its own ZKVM, all aggregated into a single proof submitted to Ethereum. This allows Aztec to inherit Ethereum's economic and censorship resistance properties.

Current throughput is not yet in the hundreds of transactions per second (TPS), as the focus is on launch and security. However, engineering improvements alone are expected to scale to 100 TPS. Achieving thousands of TPS is challenging due to privacy overheads (encrypted data, ZK proofs, peer-to-peer coordination).

For very high-throughput applications, Aztec plans to develop the AIC stack (Application-Specific Rollup Stack) post-launch. This will allow developers to build L3s using Aztec's tooling, deploy them with potentially centralized sequencers (e.g., for micropayments), and then settle blocks onto Aztec. This leverages Aztec's private state model, which allows for massive parallelism in private transactions due to the absence of race conditions.

In a success scenario, if a large percentage of L2 users demand privacy, congestion could occur, leading to increased fees (similar to Ethereum's EIP-1559 model). This is seen as a "good problem to have," indicating high demand for privacy.

Aztec's VM is not EVM-compatible. Developers must rewrite applications in Noir, Aztec's custom programming language. For the private components of transactions, there isn't a traditional VM; instead, Noir programs are directly converted into zero-knowledge circuits to maximize speed and efficiency for local proof generation on user devices.

Native Private Applications and Expanding DeFi's Design Space

The addition of privacy significantly expands DeFi's design space, enabling applications that cannot exist on transparent chains. Joe highlights several exciting categories:

Trading: Dark pools and OTC desks are being built, offering decentralized exchanges that hide trade participants or total flow, a different model from public AMMs like Uniswap.
Undercollateralized Lending and Consumer Finance: This is a highly anticipated area. Unlike traditional DeFi requiring over-collateralization, Aztec can enable loans based on a user's identity and creditworthiness. Users can feed bank statements into ZK proofs to attest to income, outgoings, and credit scores, allowing for loans based on "who I am" rather than just collateral.
Games: Various privacy-centric games are also in development.

The ZK technology also allows for selective disclosure of information. For instance, a user could generate a ZK proof to disclose a specific trade amount and date to a regulator like the IRS, proving compliance without revealing their entire transaction history. While the tooling for this needs further development, the underlying capability exists. Zach emphasizes that this enables "preemptive compliance," where transactions are only executed if all parties are proven to be compliant beforehand, a significant improvement over the current post-transaction paperwork model.

Zach illustrates a "DBank" flow on Aztec: a user logs in with a private Google authorization (account abstraction), interacts with a dark pool contract, which then calls an identity contract (e.g., ZK Passport) to verify eligibility (e.g., US citizenship for a real-world asset token). The trade executes, and the observer on the blockchain sees "absolutely nothing" – no identity, no smart contracts, no modified data.

Regulatory Landscape and the Future of Privacy

Ryan raises concerns about regulatory scrutiny, citing cases like Tornado Cash and Bitcoin privacy developers. Joe draws a parallel to the "last privacy wars" around SSL and Netscape, where encryption on the internet was fought for and won. He argues that a "weak form" of privacy (just hiding balances) is dangerous, but a "higher degree of functionality" that ties identity to accounts (like ZK Passport) can be a "force for good." Aztec aims to be a neutral infrastructure layer, empowering application developers to build with the necessary compliance tools, shifting the nexus point of responsibility from the network to the application.

Zach expresses a deeper concern: not that regulators won't understand the technology, but that they will understand it and come after Aztec because it threatens incumbent financial elites. He points to historical examples like the Genius Act, where banks resisted stablecoins. Aztec, by lowering barriers to entry for financial services, enables decentralized systems that compete directly with centralized ones. Zach believes this is a "long grinding battle of attrition," but the "too much value on the table" will ultimately force jurisdictions to embrace this technology. He is confident that Aztec is "doing everything right" to withstand such challenges.

The Aztec Journey: Motivation and Community Involvement

Zach (ex-particle physicist) and Joe (ex-material scientist) have been working on Aztec for 7-8 years, driven by a profound belief in the project's necessity. Zach states, "What else is there?" viewing it as an "opportunity of a lifetime" to pull a better world into reality. Joe is motivated by the fear of a "dystopia" where an on-chain world without strong privacy leads to MEV bots and AI agents predicting every move, and user data is "hoovered up." He feels compelled to protect the basic privacy that Western societies currently enjoy, ensuring that onboarding the unbanked to crypto rails doesn't strip them of this fundamental right.

To get involved, individuals can participate in Aztec's token sale, conducted in partnership with Uniswap using a "continuous clearing auction" model. This model prioritizes fair access and price discovery, creating a Uniswap V4 pool on Ethereum mainnet. Participants can use ZK Passport or traditional KYC. The tokens (ERC-20 on Ethereum L1) can then be staked (200,000 AZTEC required) to become a sequencer/validator, even from home using a DAT node app. Governance participation is also available for smaller token holders. The community will vote on the Token Generation Event (TGE) date, with community-purchased tokens being 100% unlocked at that time. This distribution model emphasizes "skin in the game" for network participants.

The project is currently in an "Ignition mainnet" phase, which is like a beacon chain. The next step is "Alpha," followed by "Beta" after meeting security and uptime requirements.

Conclusion: Main Takeaways

Aztec represents a significant leap forward in bringing programmable privacy to Ethereum, aiming to create a "private world computer" where users can interact with DeFi and other applications with unprecedented confidentiality. Its innovative use of ZK proofs for identity (ZK Passport) offers a robust defense against emerging threats like AI deepfakes and enables a holistic, decentralized identity model. By leveraging private intents, Aztec can blanket the entire Ethereum ecosystem with privacy without requiring a complete rebuild of DeFi, offering a positive-sum relationship with other L1s and L2s. The project's commitment to full decentralization from day one (sequencing, proving, and governance) is a bold move, driven by the belief that privacy should be a neutral, public good, akin to internet encryption. While facing technical challenges and potential regulatory headwinds, Aztec's long-term vision is to expand DeFi's design space with native private applications like undercollateralized lending and dark pools, ultimately striving to prevent a dystopian future of pervasive on-chain surveillance.