A Brief History of Aztec: The Pioneering Journey of Web3 Privacy Technology

Author: Bruce Source: X, @Bruce1_1

Without privacy, there is no freedom; without shadows, there is no light. Defending privacy is not about making a fuss, not about hosting a banquet, nor about painting or embroidering. From Article 12 of the Universal Declaration of Human Rights to the code poetry of zero-knowledge proofs, true freedom begins with the steadfast adherence to the "invisible" rights.

The privacy track lies across an invisible abyss from the mainstream values of society: the mainstream society advocates transparency and regulation, viewing them as the cornerstone of order; while privacy technology acts as a secret guardian, dedicated to protecting personal assets and data from prying eyes. Aztec, a name that draws from the mystery and power of the ancient Aztec civilization, serves not only as a moniker for a project but also as a glimpse into the future of user privacy protection. It seeks to build a bridge between the public transparency of blockchain and the individual’s need for privacy, creating a secret sanctuary for user assets and data in the gap.

Aztec's Verdant Years (2017)

Once the Aztec mainnet was launched, it became the first fully private and decentralized Layer 2 solution on Ethereum. But eight years ago, at the beginning of their entrepreneurial journey, the vision of the four founders Zac Williamson, Joe Andrews, Tom Pocock, and Arnaud Schenk was wonderfully simple - they just wanted to create a blockchain-based corporate bond issuance platform called CreditMint (which is simply not comparable to today's cool privacy protocols). At that time, zero-knowledge proofs were still lying in cryptographic papers, there was no PLONK proof system, no Noir programming language, and no one believed that on-chain privacy could become viable. But fate is so wonderful: at some corner of the coding world, this awkward "corporate bond on-chain" experiment gave birth to today's giants in the privacy track.

Although issuing bonds on-chain for medium-sized enterprises sounds like a laborious task for financial workers (compared to today's Aztec, it's like primitive farming), this unsexy project unexpectedly went viral. The team suddenly realized: without privacy protection, legitimate institutions simply dare not touch a blockchain as transparent as a glass jar! Traditional finance, though burdened by the pedantry of old-school bankers, at least can close the door and count money earnestly – thus, the seed of Aztec was sown.

This realization opened up even bigger ideas for the team: not only large institutions but also ordinary people are blocked from the blockchain by the scarcity buff of privacy technology. Thus, Aztec emerged, with a simple yet super cool concept: allowing everyone to engage in privacy transactions within a no-threshold blockchain system. This is not a joke; it could unexpectedly become the default option for online payments in the future. Just like CEO Zac Williamson's cool declaration:

“If you had programmable digital money that had privacy guarantees around it, you could use that to create extremely fast permissionless payment channels for payments on the internet.”

"If there were a programmable digital currency with built-in privacy protection, we could establish an authorization-free payment network on the internet that is lightning fast."

With the key points outlined, Zac and Joe, this golden duo, immediately divided their tasks and got to work. Zac, a former particle physics whiz, has made a glamorous transition to a cryptocurrency enthusiast, diving deep into researching the secrets of on-chain privacy; Joe, on the other hand, is spreading the word and igniting everyone's enthusiasm for this technology; while Arnaud is busy building and perfecting the CreditMint platform, also putting together the early team. In 2018, Aztec launched a "proof of concept" transaction, successfully showcasing the creation and transfer of private assets on Ethereum – using a more retro cryptographic approach rather than modern proof schemes like PLONK. Although this was just a small trial with DAI (asset privacy had been achieved, but identity privacy still needed some work), it was enough to excite the Ethereum community.

Product Demand Grows into Proof Solutions - The Birth of PLONK (2018-2020)

The 2018 version of the Aztec protocol resembles a low-level patchwork in the cryptography world: it is not smart (not programmable), not comprehensive (only supports asset privacy), and prohibitively expensive (both computational costs and gas fees are extremely high). Founder Zac humorously refers to it as a "Frankenstein pieced together with grandparent-level zk-SNARKs technology." In 2019, they created PLONK—a proof system based on SNARK that not only drastically reduces computational costs but also requires only one universal trusted setup (equivalent to providing all cryptographic circuits with a master key) to operate.

The universal trusted setup can be described as a stroke of genius; developers only need to get it right once, and all circuit programs can tap into the same set of reference strings' "WiFi". In short, PLONK has provided a permanent green light for "privacy programming" in future versions of Aztec.

The founding team, who originally intended to make PLONK an internal milestone for Aztec, found that it quickly became popular beyond expectations. Nowadays, zkSync, Polygon, and Mina are all building on its foundation, experimenting with various innovations, and even deriving a proof system called PLONKish. For Aztec itself, PLONK is zk.money

The birth of Aztec Connect paved the way - these two projects were launched in 2021 and 2022 respectively, the former being a privacy payment network and the latter a privacy DeFi Rollup. Co-founder Joe proudly announced: "PLONK was born to eliminate intermediaries!"

Ideal Shines into Reality (2021-2023)

**"Privacy Double Shot": **zk.money and Aztec Connect make a stunning debut

From 2021 to 2023, the Aztec team threw out a "privacy double cannon" - zk.money and Aztec Connect, which confirmed the market's demand for on-chain privacy as soon as the product came out, and at the same time, the team also sacrificed PLONK, an "artifact", to show the industry the feasibility of using PLONK to build a high-performance privacy network. Joe let out a bold statement: "Old and young masters, let's try to see if we can build a payment network, the user experience is as smooth as public transactions, and privacy runs quietly in the background."

These two early products directly ignited the privacy payment and DeFi markets, and the concerns about privacy regulations were instantly drowned out by the shouts of "delicious". The team knew what the market wanted, but they didn't know the market wanted it this much. At the peak, the TVL of the two Rollups surged to 20 million dollars, perfectly aligning with Zac's ultimate dream - "to make blockchain real". The team was clear in their minds: to make blockchain popular everywhere, real-world assets must be moved on-chain, and privacy protection is that sufficient and necessary condition.

Despite the market's preference and user buy-in, the team quickly realized that these two products could not achieve complete decentralization through minor adjustments. Zac and Joe are not believers in "incremental decentralization"; what they want is to be "unstoppable from the start"—a privacy network must shed the centralized "constraints" from day one. However, the sequencer of the early product still bore a centralized label, and other developers struggled to navigate Aztec's "modular programming" because all programs were crammed into a shared state.

In 2023, zk.money and Aztec Connect officially bid farewell (my burning Gas has thus generated power for love, and I pay tribute to all users who interacted with zk.money at that time; your actions can be considered as contributing the purest power for the development of privacy networks. Of course, in our own terms, this is called anti-farming.).

Noir Emerges: The "Universal Language" of Privacy

At this moment, the team started tinkering with a new toy - Noir (thanks to the original idea from Kevaundray Wedderbaum). This language, which resembles Rust, is tailored for zero-knowledge circuits, allowing ordinary developers to easily engage with privacy technology.

The original intention of tinkering with Noir was to allow everyone to write privacy programs without having to know a lot about cryptography, but the team soon got the idea: why should privacy be limited to the Aztec ecosystem? You can take Noir and make it a "universal tool – Universal Language (DSL)". Just as putting important assets on the chain makes the blockchain "real", applying zero-knowledge technology to any privacy scenario on and off the chain can also make privacy "real". Today, Noir has become an independent product stack, and the future is promising!

Today's Aztec

From 2017 to 2024, Aztec has been working to build a fully private, programmable, and decentralized blockchain network. The initial Aztec introduced asset-level privacy, but user-level privacy and programming capabilities were still far down the road. Later, PLONK emerged, like an "acceleration engine" for Aztec, directly giving rise to zk.money and Aztec Connect. Then, Noir added a new buff, making it easy for developers to build zero-knowledge applications as if they were playing with LEGO.

It is a pity that zk.money and Aztec Connect could not achieve perfection on the path to decentralization. The team learned from experience, upgraded PLONK, and with the large "developer fan base" surrounding Noir, these finally laid a solid foundation for the birth of the Aztec mainnet.

However, creating a fully privacy-guaranteed and decentralized network is no easy task. To protect privacy, all data needs to be placed in a SNARK proof system at a low cost. To truly "make blockchain real," external identity verification (such as Apple ID) must also be included in the SNARK proof. The number of statements to be expressed as provable circuits is vast, and all these functions need to operate within a decentralized network. The various challenges in mathematics, technology, and networking make this goal as challenging as interstellar travel.

The technical architecture of Aztec reflects the learning accumulation of the Aztec team. Zac describes the mainnet as a "Russian doll" - with layers nested within each other, forming a super cool privacy-focused decentralized network. The key components of Aztec now are as follows:

• Decentralized Prover and Sequencer Network: Eliminating centralized control points in one go;
• Privacy Execution Environment (PXE): Easily grasp client proofs;
• Major upgrade to the proof system: Faster, more memory-efficient, even browsers can run it smoothly!

On the network level, Aztec's decentralized landscape can be described as a shining array of stars: Prover, Sequencer, and node operators are all in action. Joe stands with one hand on his waist and the other pointing towards the mountains and rivers, speaking with a strong Hunan accent: "Decentralization of infrastructure is the first hurdle after the mainnet launch, we must ensure we do it steadily!"

With the launch of Aztec, its elegant and intelligent ambitions are no longer satisfied with the "privacy trading" track; they are targeting more dazzling application scenarios: using privacy credit scoring for consumer loans, developing information asymmetry games, and embedding privacy-protecting social applications. In the next phase, they will focus their main efforts on building a strong developer ecosystem, using Noir as the "universal key to privacy" to develop the next generation of "masterpieces" on Ethereum.

Afterword

Looking back on the history of Aztec, we will find that this is not only a protracted technological evolution, but also a profound exploration of the future of privacy, decentralization and blockchain. From the initial cry of CreditMint to the momentum of the Aztec mainnet today, the team has always sought a balance between privacy and practicality, trying to break down the barriers between traditional society and the blockchain world. The advent of PLONK and Noir not only paved the way for Aztec, but also deeply affected the privacy ecology of the entire blockchain.

True innovation often arises from a keen insight into real needs and relentless pursuit. In the game of privacy and transparency, Aztec may be opening a new chapter—ushering in an era where blockchain truly becomes "real."

When the threat of fascism intensified during World War II, then U.S. President Franklin D. Roosevelt proposed four major freedoms for human beings: Freedom of Speech, Freedom of Worship, Freedom from Want, and Freedom from Fear. Although the original purpose of the Four Freedoms was to shape a common moral vision and ideal goals for the Allies in World War II, and to call for the mobilization of the United States to the war, the Four Freedoms also provided theoretical support for the postwar human rights movement and international law, which had a far-reaching impact. And as the digital flood crosses the banks of civilization and the trajectory of carbon-based life begins to be fully built on silicon-based facilities, we urgently need to write the fifth chapter of Roosevelt's four freedoms - Freedom from Surveillance. Just as freedom of expression needs to break free from the physical shackles, freedom of privacy aims to break the invisible cage of data; Just as freedom from want calls for economic justice, freedom from prying eyes demands the distribution of dignity in the information age. When cameras become clairvoyant eyes and algorithms become mind-reading, this freedom, which may have to be defended by code, becomes a digital fortress that maintains the integrity of modern man. From the Universal Declaration of Human Rights to the European Union's General Data Protection Regulation, from end-to-end encryption to zero-knowledge proofs, humanity is using a new cryptographic shield to defend digital frontiers that Roosevelt did not foresee. History always moves forward in cycles: if the Four Freedoms were the torch of the 20th century against violent totalitarianism, the freedom of privacy is the spear of light against the digital Leviathan in the 21st century – the two complement each other, illuminating the same path to freedom.

Glossary of Terms

• Layer 2 (L2): An expansion solution built on top of the main chain (such as Ethereum), which enhances transaction speed and reduces costs, while relying on the security of the main chain.
• Zero-Knowledge Proof: A cryptographic method that allows the prover to convince the verifier of a fact without revealing any additional information.
• PLONK: An efficient zk-SNARK proof system that requires only one universal trusted setup and supports the development of various privacy programs.
• Noir: A programming language specifically designed for writing zero-knowledge circuit designs, making it easier for developers to create privacy applications.
• zk-SNARK: A zero-knowledge proof protocol used to verify the correctness of transactions or computations while protecting privacy.
• Rollup: A Layer 2 technology that bundles multiple transactions and verifies them on the main chain to improve efficiency.
• DeFi (Decentralized Finance): Financial services based on blockchain, running through smart contracts without the need for traditional intermediaries.
• TVL (Total Value Locked): The total value of assets locked in DeFi projects, reflecting their scale and user participation.
• Sequencer: The component responsible for collecting, ordering, and submitting transactions in a Rollup network.
• Prover: The party that generates the proof in a zero-knowledge proof system.
• PXE (Privacy Execution Environment): A client environment used in Aztec for privacy computing, supporting local proof generation.
• DSL (Domain-Specific Language): A programming language designed for a specific domain, such as Noir for zero-knowledge applications.
• Kevaundray Wedderburn: Born in January 1996 in London, UK, he is a software developer focused on blockchain privacy technologies. He is known for creating the Noir language and has contributed significant code to the Aztec project and the Ethereum community, promoting the adoption of zero-knowledge proof technologies.