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Inside Aztec
Inside
Aztec
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Building a fully decentralized, privacy-preserving network to unlock the next Renaissance.
Privacy has emerged as a major driver for the crypto industry in 2025. We’ve seen the explosion of Zcash, the Ethereum Foundation’s refocusing of PSE, and the launch of Aztec’s testnet with over 24,000 validators powering the network. Many apps have also emerged to bring private transactions to Ethereum and Solana in various ways, and exciting technologies like ZKPassport that privately bring identity on-chain using Noir have become some of the most talked about developments for ushering in the next big movements to the space.
Underpinning all of these developments is the emerging consensus that without privacy, blockchains will struggle to gain real-world adoption.
Without privacy, institutions can’t bring assets on-chain in a compliant way or conduct complex swaps and trades without revealing their strategies. Without privacy, DeFi remains dominated and controlled by advanced traders who can see all upcoming transactions and manipulate the market. Without privacy, regular people will not want to move their lives on-chain for the entire world to see every detail about their every move.
While there's been lots of talk about privacy, few can define it. In this piece we’ll outline the three pillars of privacy and gives you a framework for evaluating the privacy claims of any project.
True privacy rests on three essential pillars: transaction privacy, identity privacy, and computational privacy. It is only when we have all three pillars that we see the emergence of a private world computer.
Transaction privacy means that both inputs and outputs are not viewable by anyone other than the intended participants. Inputs include any asset, value, message, or function calldata that is being sent. Outputs include any state changes or transaction effects, or any transaction metadata caused by the transaction. Transaction privacy is often primarily achieved using a UTXO model (like Zcash or Aztec’s private state tree). If a project has only the option for this pillar, it can be said to be confidential, but not private.
Identity privacy means that the identities of those involved are not viewable by anyone other than the intended participants. This includes addresses or accounts and any information about the identity of the participants, such as tx.origin, msg.sender, or linking one’s private account to public accounts. Identity privacy can be achieved in several ways, including client-side proof generation that keeps all user info on the users’ devices. If a project has only the option for this pillar, it can be said to be anonymous, but not private.
Computation privacy means that any activity that happens is not viewable by anyone other than the intended participants. This includes the contract code itself, function execution, contract address, and full callstack privacy. Additionally, any metadata generated by the transaction is able to be appropriately obfuscated (such as transaction effects, events are appropriately padded, inclusion block number are in appropriate sets). Callstack privacy includes which contracts you call, what functions in those contracts you’ve called, what the results of those functions were, any subsequent functions that will be called after, and what the inputs to the function were. A project must have the option for this pillar to do anything privately other than basic transactions.
Bitcoin ushered in a new paradigm of digital money. As a permissionless, peer-to-peer currency and store of value, it changed the way value could be sent around the world and who could participate. Ethereum expanded this vision to bring us the world computer, a decentralized, general-purpose blockchain with programmable smart contracts.
Given the limitations of running a transparent blockchain that exposes all user activity, accounts, and assets, it was clear that adding the option to preserve privacy would unlock many benefits (and more closely resemble real cash). But this was a very challenging problem. Zcash was one of the first to extend Bitcoin’s functionality with optional privacy, unlocking a new privacy-preserving UTXO model for transacting privately. As we’ll see below, many of the current privacy-focused projects are working on similar kinds of private digital money for Ethereum or other chains.
Now, Aztec is bringing us the final missing piece: a private world computer.
A private world computer is fully decentralized, programmable, and permissionless like Ethereum and has optional privacy at every level. In other words, Aztec is extending all the functionality of Ethereum with optional transaction, identity, and computational privacy. This is the only approach that enables fully compliant, decentralized applications to be built that preserve user privacy, a new design space that we see as ushering in the next Renaissance for the space.
Private digital money emerges when you have the first two privacy pillars covered - transactions and identity - but you don’t have the third - computation. Almost all projects today that claim some level of privacy are working on private digital money. This includes everything from privacy pools on Ethereum and L2s to newly emerging payment L1s like Tempo and Arc that are developing various degrees of transaction privacy
When it comes to digital money, privacy exists on a spectrum. If your identity is hidden but your transactions are visible, that's what we call anonymous. If your transactions are hidden but your identity is known, that's confidential. And when both your identity and transactions are protected, that's true privacy. Projects are working on many different approaches to implement this, from PSE to Payy using Noir, the zkDSL built to make it intuitive to build zk applications using familiar Rust-like syntax.
Private digital money is designed to make payments private, but any interaction with more complex smart contracts than a straightforward payment transaction is fully exposed.
What if we also want to build decentralized private apps using smart contracts (usually multiple that talk to each other)? For this, you need all three privacy pillars: transaction, identity, and compute.
If you have these three pillars covered and you have decentralization, you have built a private world computer. Without decentralization, you are vulnerable to censorship, privileged backdoors and inevitable centralized control that can compromise privacy guarantees.
What exactly is a private world computer? A private world computer extends all the functionality of Ethereum with optional privacy at every level, so developers can easily control which aspects they want public or private and users can selectively disclose information. With Aztec, developers can build apps with optional transaction, identity, and compute privacy on a fully decentralized network. Below, we’ll break down the main components of a private world computer.
A private world computer is powered by private smart contracts. Private smart contracts have fully optional privacy and also enable seamless public and private function interaction.
Private smart contracts simply extend the functionality of regular smart contracts with added privacy.
As a developer, you can easily designate which functions you want to keep private and which you want to make public. For example, a voting app might allow users to privately cast votes and publicly display the result. Private smart contracts can also interact privately with other smart contracts, without needing to make it public which contracts have interacted.
Transaction: Aztec supports the optionality for fully private inputs, including messages, state, and function calldata. Private state is updated via a private UTXO state tree.
Identity: Using client-side proofs and function execution, Aztec can optionally keep all user info private, including tx.origin and msg.sender for transactions.
Computation: The contract code itself, function execution, and call stack can all be kept private. This includes which contracts you call, what functions in those contracts you’ve called, what the results of those functions were, and what the inputs to the function were.
A decentralized network must be made up of a permissionless network of operators who run the network and decide on upgrades. Aztec is run by a decentralized network of node operators who propose and attest to transactions. Rollup proofs on Aztec are also run by a decentralized prover network that can permissionlessly submit proofs and participate in block rewards. Finally, the Aztec network is governed by the sequencers, who propose, signal, vote, and execute network upgrades.
A private world computer enables the creation of DeFi applications where accounts, transactions, order books, and swaps remain private. Users can protect their trading strategies and positions from public view, preventing front-running and maintaining competitive advantages. Additionally, users can bridge privately into cross-chain DeFi applications, allowing them to participate in DeFi across multiple blockchains while keeping their identity private despite being on an existing transparent blockchain.
This technology makes it possible to bring institutional trading activity on-chain while maintaining the privacy that traditional finance requires. Institutions can privately trade with other institutions globally, without having to touch public markets, enjoying the benefits of blockchain technology such as fast settlement and reduced counterparty risk, without exposing their trading intentions or volumes to the broader market.
Organizations can bring client accounts and assets on-chain while maintaining full compliance. This infrastructure protects on-chain asset trading and settlement strategies, ensuring that sophisticated financial operations remain private. A private world computer also supports private stablecoin issuance and redemption, allowing financial institutions to manage digital currency operations without revealing sensitive business information.
Users have granular control over their privacy settings, allowing them to fine-tune privacy levels for their on-chain identity according to their specific needs. The system enables selective disclosure of on-chain activity, meaning users can choose to reveal certain transactions or holdings to regulators, auditors, or business partners while keeping other information private, meeting compliance requirements.
The shift from transparent blockchains to privacy-preserving infrastructure is the foundation for bringing the next billion users on-chain. Whether you're a developer building the future of private DeFi, an institution exploring compliant on-chain solutions, or simply someone who believes privacy is a fundamental right, now is the time to get involved.
Follow Aztec on X to stay updated on the latest developments in private smart contracts and decentralized privacy technology. Ready to contribute to the network? Run a node and help power the private world computer.
The next Renaissance is here, and it’s being powered by the private world computer.
Special thanks to Santiago Palladino, Phil Windle, Alex Gherghisan, and Mitch Tracy for technical updates and review.
On September 17th, 2025, a new network upgrade was deployed, making Aztec more secure and flexible for home stakers. This upgrade, shipped with all the features needed for a fully decentralized network launch, includes a completely redesigned slashing system that allows inactive or malicious operators to be removed, and does not penalize home stakers for short outages.
With over 23,000 operators running validators across 6 continents (in a variety of conditions), it is critical not to penalize nodes that temporarily drop due to internet connectivity issues. This is because users of the network are also found across the globe, some of whom might have older phones. A significant effort was put into shipping a low-memory proving mode that allows older mobile devices to send transactions and use privacy-preserving apps.
The network was successfully deployed, and all active validators on the old testnet were added to the queue of the new testnet. This manual migration was only necessary because major upgrades to the governance contracts had gone in since the last testnet was deployed. The new testnet started producing blocks after the queue started to be “flushed,” moving validators into the rollup. Because the network is fully decentralized, the initial flush could have been called by anyone. The network produced ~2k blocks before an invalid block made it to the chain and temporarily stalled block production. Block production is now restored and the network is healthy. This post explains what caused the issue and provides an update on the current status of the network.
Note: if you are a network operator, you must upgrade to version 2.0.3 and restart your node to participate in the latest testnet. If you want to run a node, it’s easy to get started.
This upgrade was a team-wide effort that optimized performance and implemented all the mechanisms needed to launch Aztec as a fully decentralized network from day 1.
With these updates in place, we’re ready to test a feature-complete network.
As mentioned above, block production started when someone called the flush function and a minimum number of operators from the queue were let into the validator set.
Shortly thereafter, while testing the network, a member of the Aztec Labs team spun up a “bad” sequencer that produced an invalid block proposal. Specifically, one of the state trees in the proposal was tampered with.
The expectation was that this would be detected immediately and the block rejected. Instead, a bug was discovered in the validator code where the invalid block proposal wasn't checked thoroughly enough. In effect, the proposal got enough attestations, so it was posted to the rollup. Due to extra checks in the nodes, when the nodes pulled the invalid block from Ethereum, they detected the tampered tree and refused to sync it. This is a good outcome as it prevented the attack. Additionally, prover nodes refused to prove the epoch containing the invalid block. This allowed the rollup to prune the entire bad epoch away. After the prune, the invalid state was reset to the last known good block.
The prune revealed another, smaller bug, where, after a failed block sync, a prune does not get processed correctly, requiring a node restart to clear up. This led to a 90-minute outage from the moment the block proposal was posted until the testnet recovered. The time was equally split between waiting for pruning to happen and for the nodes to restart in order to process the prune.
Validators were correctly re-executing all transactions in the block proposals and verifying that the world state root matched the one in the block proposal, but they failed to check that intermediate tree roots, which are included in the proposal and posted to the rollup contract on L1, were also correct. The attack tweaked one of these intermediate roots while proposing a correct world state root, so it went unnoticed by the attestors.
As mentioned above, even though the block made it through the initial attestation and was posted to L1, the invalid block was caught by the validators, and the entire epoch was never proven as provers refused to generate a proof for the inconsistent state.
A fix was pushed that resolved this issue and ensured that invalid block proposals would be caught and rejected. A second fix was pushed that ensures inconsistent state is removed from the uncommitted cache of the world state.
Block production is currently running smoothly, and the network health has been restored.
Operators who had previously upgraded to version 2.0.3 will need to restart their nodes. Any operator who has not upgraded to 2.0.3 should do so immediately.
Slashing has also been functioning as expected. Below you can see the slashing signals for each round. A single signal can contain votes for multiple validators, but a validator's attester needs to receive 65 votes to be slashed.
Join us this Thursday, September 25, 2025, at 4 PM CET on the Discord Town Hall to hear more about the 2.0.3 upgrade. To stay up to date with the latest updates for network operators, join the Aztec Discord and follow Aztec on X.
Payy, a privacy-focused payment network, just rewrote its entire ZK architecture from Halo2 to Noir while keeping its network live, funds safe, and users happy.
Code that took months to write now takes weeks (with MVPs built in as little as 30 minutes). Payy’s codebase shrank from thousands of lines to 250, and now their entire engineering team can actually work on its privacy infra.
This is the story of how they transformed their ZK ecosystem from one bottlenecked by a single developer to a system their entire team can modify and maintain.
Eighteen months ago, Payy faced a deceptively simple requirement: build a privacy-preserving payment network that actually works on phones. That requires client-side proving.
"Anyone who tells you they can give you privacy without the proof being on the phone is lying to you," Calum Moore - Payy's Technical Lead - states bluntly.
To make a private, mobile network work, they needed:
To start, the team evaluated available ZK stacks through their zkbench framework:
STARKs (e.g., RISC Zero): Memory requirements made them a non-starter on mobile. Large proof sizes are unsuitable for mobile data transmission.
Circom with Groth16: Required trusted setup ceremonies for each circuit update. It had “abstracted a bit too early” and, as a result, is not high-level enough to develop comfortably, but not low-level enough for controls and optimizations, said Calum.
Halo2: Selected based on existing production deployments (ZCash, Scroll), small proof sizes, and an existing Ethereum verifier. As Calum admitted with the wisdom of hindsight: “Back a year and a half ago, there weren’t any other real options.”
Halo2 delivered on its promises: Payy successfully launched its network. But cracks started showing almost immediately.
First, they had to write their own chips from scratch. Then came the real fun: if statements.
"With Halo2, I'm building a chip, I'm passing this chip in... It's basically a container chip, so you'd set the value to zero or one depending on which way you want it to go. And, you'd zero out the previous value if you didn't want it to make a difference to the calculation," Calum explained, “when I’m writing in Noir, I just write ‘if’. "
With Halo2, writing an if statement (programming 101) required building custom chip infra.
Binary decomposition, another fundamental operation for rollups, meant more custom chips. The Halo2 implementation quickly grew to thousands of lines of incomprehensible code.
And only Calum could touch any of it.
The Bottleneck
"It became this black box that no one could touch, no one could reason about, no one could verify," he recalls. "Obviously, we had it audited, and we were confident in that. But any changes could only be done by me, could only be verified by me or an auditor."
In engineering terms, this is called a bus factor of one: if Calum got hit by a bus (or took a vacation to Argentina), Payy's entire proving system would be frozen. "Those circuits are open source," Calum notes wryly, "but who's gonna be able to read the Halo2 circuits? Nobody."
During a launch event in Argentina, "I was like, oh, I'll check out Noir again. See how it's going," Calum remembers. He'd been tracking Noir's progress for months, occasionally testing it out, waiting for it to be reliable.
"I wrote basically our entire client-side proof in about half an hour in Noir. And it probably took me - I don't know, three weeks to write that proof originally in Halo2."
Calum recreated Payy's client-side proof in Noir in 30 minutes. And when he tested the proving speed, without any optimization, they were seeing 2x speed improvements.
"I kind of internally… didn't want to tell my cofounder Sid that I'd already made my decision to move to Noir," Calum admits. "I hadn't broken it to him yet because it's hard to justify rewriting your proof system when you have a deployed network with a bunch of money already on the network and a bunch of users."
Convincing a team to rewrite the core of a live financial network takes some evidence. The technical evaluation of Noir revealed improvements across every metric:
Proof Generation Time: Sub-0.5 second proof generation on iPhones. "We're obsessive about performance," Calum notes (they’re confident they can push it even further).
Code Complexity: Their entire ZK implementation compressed from thousands of lines of Halo2 to just 250 lines of Noir code. "With rollups, the logic isn't complex—it's more about the preciseness of the logic," Calum explains.
Composability: In Halo2, proof aggregation required hardwiring specific verifiers for each proof type. Noir offers a general-purpose verifier that accepts any proof of consistent size.
"We can have 100 different proving systems, which are hyper-efficient for the kind of application that we're doing," Calum explains. "Have them all aggregated by the same aggregation proof, and reason about whatever needs to be."
Initially, the goal was to "completely mirror our Halo2 proofs": no new features. This conservative approach meant they could verify correctness while maintaining a live network.
The migration preserved Payy's production architecture:
"If you have your proofs in Noir, any person who understands even a little bit about logic or computers can go in and say, 'okay, I can kinda see what's happening here'," Calum notes.
The audit process completely transformed. With Halo2: "The auditors that are available to audit Halo2 are few and far between."
With Noir: "You could have an auditor that had no Noir experience do at least a 95% job."
Why? Most audit issues are logic errors, not ZK-specific bugs. When auditors can read your code, they find real problems instead of getting lost in implementation details.
Halo2: Binary decomposition
Payy’s previous 383 line implementation of binary decomposition can be viewed here (pkg/zk-circuits/src/chips/binary_decomposition.rs).
Payy’s previous binary decomposition implementation
Meanwhile, binary decomposition is handled in Noir with the following single line.
pub fn to_le_bits<let N: u32>(self: Self) -> [u1; N]
(Source)
With Noir's composable proof system, Payy can now build specialized provers for different operations, each optimized for its specific task.
"If statements are horrendous in SNARKs because you pay the cost of the if statement regardless of its run," Calum explains. But with Noir's approach, "you can split your application logic into separate proofs, and run whichever proof is for the specific application you're looking for."
Instead of one monolithic proof trying to handle every case, you can have specialized proofs, each perfect for its purpose.
"I fell a little bit in love with Halo2," Calum admits, "maybe it's Stockholm syndrome where you're like, you know, it's a love-hate relationship, and it's really hard. But at the same time, when you get a breakthrough with it, you're like, yes, I feel really good because I'm basically writing assembly-level ZK proofs."
“But now? I just write ‘if’.”
Technical Note: While "migrating from Halo2 to Noir" is shorthand that works for this article, technically Halo2 is an integrated proving system where circuits must be written directly in Rust using its constraint APIs, while Noir is a high-level language that compiles to an intermediate representation and can use various proving backends. Payy specifically moved from writing circuits in Halo2's low-level constraint system to writing them in Noir's high-level language, with Barretenberg (UltraHonk) as their proving backend.
Both tools ultimately enable developers to write circuits and generate proofs, but Noir's modular architecture separates circuit logic from the proving system - which is what made Payy's circuits so much more accessible to their entire team, and now allows them to swap out their proving system with minimal effort as proving systems improve.
Payy's code is open source and available for developers looking to learn from their implementation.
After eight years of solving impossible problems, the next renaissance is here.
We’re at a major inflection point, with both our tech and our builder community going through growth spurts. The purpose of this rebrand is simple: to draw attention to our full-stack privacy-native network and to elevate the rich community of builders who are creating a thriving ecosystem around it.
For eight years, we’ve been obsessed with solving impossible challenges. We invented new cryptography (Plonk), created an intuitive programming language (Noir), and built the first decentralized network on Ethereum where privacy is native rather than an afterthought.
It wasn't easy. But now, we're finally bringing that powerful network to life. Testnet is live with thousands of active users and projects that were technically impossible before Aztec.
Our community evolution mirrors our technical progress. What started as an intentionally small, highly engaged group of cracked developers is now welcoming waves of developers eager to build applications that mainstream users actually want and need.
A brand is more than aesthetics—it's a mental model that makes Aztec's spirit tangible.
Renaissance means "rebirth"—and that's exactly what happens when developers gain access to privacy-first infrastructure. We're witnessing the emergence of entirely new application categories, business models, and user experiences.
The faces of this renaissance are the builders we serve: the entrepreneurs building privacy-preserving DeFi, the activists building identity systems that protect user privacy, the enterprise architects tokenizing real-world assets, and the game developers creating experiences with hidden information.
This next renaissance isn't just about technology—it's about the ethos behind the build. These aren't just our values. They're the shared DNA of every builder pushing the boundaries of what's possible on Aztec.
Agency: It’s what everyone deserves, and very few truly have: the ability to choose and take action for ourselves. On the Aztec Network, agency is native
Genius: That rare cocktail of existential thirst, extraordinary brilliance, and mind-bending creation. It’s fire that fuels our great leaps forward.
Integrity: It’s the respect and compassion we show each other. Our commitment to attacking the hardest problems first, and the excellence we demand of any solution.
Obsession: That highly concentrated insanity, extreme doggedness, and insatiable devotion that makes us tick. We believe in a different future—and we can make it happen, together.
Just as our technology bridges different eras of cryptographic innovation, our new visual identity draws from multiple periods of human creativity and technological advancement.
Our new wordmark embodies the diversity of our community and the permissionless nature of our network. Each letter was custom-drawn to reflect different pivotal moments in human communication and technological progress.
Together, these letters tell the story of human innovation: each era building on the last, each breakthrough enabling the next renaissance. And now, we're building the infrastructure for the one that's coming.
We evolved our original icon to reflect this new chapter while honoring our foundation. The layered diamond structure tells the story:
The architecture echoes a central plaza—the Roman forum, the Greek agora, the English commons, the American town square—places where people gather, exchange ideas, build relationships, and shape culture. It's a fitting symbol for the infrastructure enabling the next leap in human coordination and creativity.
From the Mughal and Edo periods to the Flemish and Italian Renaissance, our brand imagery draws from different cultures and eras of extraordinary human flourishing—periods when science, commerce, culture and technology converged to create unprecedented leaps forward. These visuals reflect both the universal nature of the Renaissance and the global reach of our network.
But we're not just celebrating the past —we're creating the future: the infrastructure for humanity's next great creative and technological awakening, powered by privacy-native blockchain technology.
Join us to ask questions, learn more and dive into the lore.
Join Our Discord Town Hall. September 4th at 8 AM PT, then every Thursday at 7 AM PT. Come hear directly from our team, ask questions, and connect with other builders who are shaping the future of privacy-first applications.
Take your stance on privacy. Visit the privacy glyph generator to create your custom profile pic and build this new world with us.
Stay Connected. Visit the new website and to stay up-to-date on all things Noir and Aztec, make sure you’re following along on X.
The next renaissance is what you build on Aztec—and we can't wait to see what you'll create.
Aztec’s Public Testnet launched in May 2025.
Since then, we’ve been obsessively working toward our ultimate goal: launching the first fully decentralized privacy-preserving layer-2 (L2) network on Ethereum. This effort has involved a team of over 70 people, including world-renowned cryptographers and builders, with extensive collaboration from the Aztec community.
To make something private is one thing, but to also make it decentralized is another. Privacy is only half of the story. Every component of the Aztec Network will be decentralized from day one because decentralization is the foundation that allows privacy to be enforced by code, not by trust. This includes sequencers, which order and validate transactions, provers, which create privacy-preserving cryptographic proofs, and settlement on Ethereum, which finalizes transactions on the secure Ethereum mainnet to ensure trust and immutability.
Strong progress is being made by the community toward full decentralization. The Aztec Network now includes nearly 1,000 sequencers in its validator set, with 15,000 nodes spread across more than 50 countries on six continents. With this globally distributed network in place, the Aztec Network is ready for users to stress test and challenge its resilience.
We're now entering a new phase: the Adversarial Testnet. This stage will test the resilience of the Aztec Testnet and its decentralization mechanisms.
The Adversarial Testnet introduces two key features: slashing, which penalizes validators for malicious or negligent behavior in Proof-of-Stake (PoS) networks, and a fully decentralized governance mechanism for protocol upgrades.
This phase will also simulate network attacks to test its ability to recover independently, ensuring it could continue to operate even if the core team and servers disappeared (see more on Vitalik’s “walkaway test” here). It also opens the validator set to more people using ZKPassport, a private identity verification app, to verify their identity online.
The Aztec Network testnet is decentralized, run by a permissionless network of sequencers.
The slashing upgrade tests one of the most fundamental mechanisms for removing inactive or malicious sequencers from the validator set, an essential step toward strengthening decentralization.
Similar to Ethereum, on the Aztec Network, any inactive or malicious sequencers will be slashed and removed from the validator set. Sequencers will be able to slash any validator that makes no attestations for an entire epoch or proposes an invalid block.
Three slashes will result in being removed from the validator set. Sequencers may rejoin the validator set at any time after getting slashed; they just need to rejoin the queue.
In addition to testing network resilience when validators go offline and evaluating the slashing mechanisms, the Adversarial Testnet will also assess the robustness of the network’s decentralized governance during protocol upgrades.
Adversarial Testnet introduces changes to Aztec Network’s governance system.
Sequencers now have an even more central role, as they are the sole actors permitted to deposit assets into the Governance contract.
After the upgrade is defined and the proposed contracts are deployed, sequencers will vote on and implement the upgrade independently, without any involvement from Aztec Labs and/or the Aztec Foundation.
Starting today, you can join the Adversarial Testnet to help battle-test Aztec’s decentralization and security. Anyone can compete in six categories for a chance to win exclusive Aztec swag, be featured on the Aztec X account, and earn a DappNode. The six challenge categories include:
Performance will be tracked using Dashtec, a community-built dashboard that pulls data from publicly available sources. Dashtec displays a weighted score of your validator performance, which may be used to evaluate challenges and award prizes.
The dashboard offers detailed insights into sequencer performance through a stunning UI, allowing users to see exactly who is in the current validator set and providing a block-by-block view of every action taken by sequencers.
To join the validator set and start tracking your performance, click here. Join us on Thursday, July 31, 2025, at 4 pm CET on Discord for a Town Hall to hear more about the challenges and prizes. Who knows, we might even drop some alpha.
To stay up-to-date on all things Noir and Aztec, make sure you’re following along on X.
Privacy has emerged as a major driver for the crypto industry in 2025. We’ve seen the explosion of Zcash, the Ethereum Foundation’s refocusing of PSE, and the launch of Aztec’s testnet with over 24,000 validators powering the network. Many apps have also emerged to bring private transactions to Ethereum and Solana in various ways, and exciting technologies like ZKPassport that privately bring identity on-chain using Noir have become some of the most talked about developments for ushering in the next big movements to the space.
Underpinning all of these developments is the emerging consensus that without privacy, blockchains will struggle to gain real-world adoption.
Without privacy, institutions can’t bring assets on-chain in a compliant way or conduct complex swaps and trades without revealing their strategies. Without privacy, DeFi remains dominated and controlled by advanced traders who can see all upcoming transactions and manipulate the market. Without privacy, regular people will not want to move their lives on-chain for the entire world to see every detail about their every move.
While there's been lots of talk about privacy, few can define it. In this piece we’ll outline the three pillars of privacy and gives you a framework for evaluating the privacy claims of any project.
True privacy rests on three essential pillars: transaction privacy, identity privacy, and computational privacy. It is only when we have all three pillars that we see the emergence of a private world computer.
Transaction privacy means that both inputs and outputs are not viewable by anyone other than the intended participants. Inputs include any asset, value, message, or function calldata that is being sent. Outputs include any state changes or transaction effects, or any transaction metadata caused by the transaction. Transaction privacy is often primarily achieved using a UTXO model (like Zcash or Aztec’s private state tree). If a project has only the option for this pillar, it can be said to be confidential, but not private.
Identity privacy means that the identities of those involved are not viewable by anyone other than the intended participants. This includes addresses or accounts and any information about the identity of the participants, such as tx.origin, msg.sender, or linking one’s private account to public accounts. Identity privacy can be achieved in several ways, including client-side proof generation that keeps all user info on the users’ devices. If a project has only the option for this pillar, it can be said to be anonymous, but not private.
Computation privacy means that any activity that happens is not viewable by anyone other than the intended participants. This includes the contract code itself, function execution, contract address, and full callstack privacy. Additionally, any metadata generated by the transaction is able to be appropriately obfuscated (such as transaction effects, events are appropriately padded, inclusion block number are in appropriate sets). Callstack privacy includes which contracts you call, what functions in those contracts you’ve called, what the results of those functions were, any subsequent functions that will be called after, and what the inputs to the function were. A project must have the option for this pillar to do anything privately other than basic transactions.
Bitcoin ushered in a new paradigm of digital money. As a permissionless, peer-to-peer currency and store of value, it changed the way value could be sent around the world and who could participate. Ethereum expanded this vision to bring us the world computer, a decentralized, general-purpose blockchain with programmable smart contracts.
Given the limitations of running a transparent blockchain that exposes all user activity, accounts, and assets, it was clear that adding the option to preserve privacy would unlock many benefits (and more closely resemble real cash). But this was a very challenging problem. Zcash was one of the first to extend Bitcoin’s functionality with optional privacy, unlocking a new privacy-preserving UTXO model for transacting privately. As we’ll see below, many of the current privacy-focused projects are working on similar kinds of private digital money for Ethereum or other chains.
Now, Aztec is bringing us the final missing piece: a private world computer.
A private world computer is fully decentralized, programmable, and permissionless like Ethereum and has optional privacy at every level. In other words, Aztec is extending all the functionality of Ethereum with optional transaction, identity, and computational privacy. This is the only approach that enables fully compliant, decentralized applications to be built that preserve user privacy, a new design space that we see as ushering in the next Renaissance for the space.
Private digital money emerges when you have the first two privacy pillars covered - transactions and identity - but you don’t have the third - computation. Almost all projects today that claim some level of privacy are working on private digital money. This includes everything from privacy pools on Ethereum and L2s to newly emerging payment L1s like Tempo and Arc that are developing various degrees of transaction privacy
When it comes to digital money, privacy exists on a spectrum. If your identity is hidden but your transactions are visible, that's what we call anonymous. If your transactions are hidden but your identity is known, that's confidential. And when both your identity and transactions are protected, that's true privacy. Projects are working on many different approaches to implement this, from PSE to Payy using Noir, the zkDSL built to make it intuitive to build zk applications using familiar Rust-like syntax.
Private digital money is designed to make payments private, but any interaction with more complex smart contracts than a straightforward payment transaction is fully exposed.
What if we also want to build decentralized private apps using smart contracts (usually multiple that talk to each other)? For this, you need all three privacy pillars: transaction, identity, and compute.
If you have these three pillars covered and you have decentralization, you have built a private world computer. Without decentralization, you are vulnerable to censorship, privileged backdoors and inevitable centralized control that can compromise privacy guarantees.
What exactly is a private world computer? A private world computer extends all the functionality of Ethereum with optional privacy at every level, so developers can easily control which aspects they want public or private and users can selectively disclose information. With Aztec, developers can build apps with optional transaction, identity, and compute privacy on a fully decentralized network. Below, we’ll break down the main components of a private world computer.
A private world computer is powered by private smart contracts. Private smart contracts have fully optional privacy and also enable seamless public and private function interaction.
Private smart contracts simply extend the functionality of regular smart contracts with added privacy.
As a developer, you can easily designate which functions you want to keep private and which you want to make public. For example, a voting app might allow users to privately cast votes and publicly display the result. Private smart contracts can also interact privately with other smart contracts, without needing to make it public which contracts have interacted.
Transaction: Aztec supports the optionality for fully private inputs, including messages, state, and function calldata. Private state is updated via a private UTXO state tree.
Identity: Using client-side proofs and function execution, Aztec can optionally keep all user info private, including tx.origin and msg.sender for transactions.
Computation: The contract code itself, function execution, and call stack can all be kept private. This includes which contracts you call, what functions in those contracts you’ve called, what the results of those functions were, and what the inputs to the function were.
A decentralized network must be made up of a permissionless network of operators who run the network and decide on upgrades. Aztec is run by a decentralized network of node operators who propose and attest to transactions. Rollup proofs on Aztec are also run by a decentralized prover network that can permissionlessly submit proofs and participate in block rewards. Finally, the Aztec network is governed by the sequencers, who propose, signal, vote, and execute network upgrades.
A private world computer enables the creation of DeFi applications where accounts, transactions, order books, and swaps remain private. Users can protect their trading strategies and positions from public view, preventing front-running and maintaining competitive advantages. Additionally, users can bridge privately into cross-chain DeFi applications, allowing them to participate in DeFi across multiple blockchains while keeping their identity private despite being on an existing transparent blockchain.
This technology makes it possible to bring institutional trading activity on-chain while maintaining the privacy that traditional finance requires. Institutions can privately trade with other institutions globally, without having to touch public markets, enjoying the benefits of blockchain technology such as fast settlement and reduced counterparty risk, without exposing their trading intentions or volumes to the broader market.
Organizations can bring client accounts and assets on-chain while maintaining full compliance. This infrastructure protects on-chain asset trading and settlement strategies, ensuring that sophisticated financial operations remain private. A private world computer also supports private stablecoin issuance and redemption, allowing financial institutions to manage digital currency operations without revealing sensitive business information.
Users have granular control over their privacy settings, allowing them to fine-tune privacy levels for their on-chain identity according to their specific needs. The system enables selective disclosure of on-chain activity, meaning users can choose to reveal certain transactions or holdings to regulators, auditors, or business partners while keeping other information private, meeting compliance requirements.
The shift from transparent blockchains to privacy-preserving infrastructure is the foundation for bringing the next billion users on-chain. Whether you're a developer building the future of private DeFi, an institution exploring compliant on-chain solutions, or simply someone who believes privacy is a fundamental right, now is the time to get involved.
Follow Aztec on X to stay updated on the latest developments in private smart contracts and decentralized privacy technology. Ready to contribute to the network? Run a node and help power the private world computer.
The next Renaissance is here, and it’s being powered by the private world computer.
After eight years of solving impossible problems, the next renaissance is here.
We’re at a major inflection point, with both our tech and our builder community going through growth spurts. The purpose of this rebrand is simple: to draw attention to our full-stack privacy-native network and to elevate the rich community of builders who are creating a thriving ecosystem around it.
For eight years, we’ve been obsessed with solving impossible challenges. We invented new cryptography (Plonk), created an intuitive programming language (Noir), and built the first decentralized network on Ethereum where privacy is native rather than an afterthought.
It wasn't easy. But now, we're finally bringing that powerful network to life. Testnet is live with thousands of active users and projects that were technically impossible before Aztec.
Our community evolution mirrors our technical progress. What started as an intentionally small, highly engaged group of cracked developers is now welcoming waves of developers eager to build applications that mainstream users actually want and need.
A brand is more than aesthetics—it's a mental model that makes Aztec's spirit tangible.
Renaissance means "rebirth"—and that's exactly what happens when developers gain access to privacy-first infrastructure. We're witnessing the emergence of entirely new application categories, business models, and user experiences.
The faces of this renaissance are the builders we serve: the entrepreneurs building privacy-preserving DeFi, the activists building identity systems that protect user privacy, the enterprise architects tokenizing real-world assets, and the game developers creating experiences with hidden information.
This next renaissance isn't just about technology—it's about the ethos behind the build. These aren't just our values. They're the shared DNA of every builder pushing the boundaries of what's possible on Aztec.
Agency: It’s what everyone deserves, and very few truly have: the ability to choose and take action for ourselves. On the Aztec Network, agency is native
Genius: That rare cocktail of existential thirst, extraordinary brilliance, and mind-bending creation. It’s fire that fuels our great leaps forward.
Integrity: It’s the respect and compassion we show each other. Our commitment to attacking the hardest problems first, and the excellence we demand of any solution.
Obsession: That highly concentrated insanity, extreme doggedness, and insatiable devotion that makes us tick. We believe in a different future—and we can make it happen, together.
Just as our technology bridges different eras of cryptographic innovation, our new visual identity draws from multiple periods of human creativity and technological advancement.
Our new wordmark embodies the diversity of our community and the permissionless nature of our network. Each letter was custom-drawn to reflect different pivotal moments in human communication and technological progress.
Together, these letters tell the story of human innovation: each era building on the last, each breakthrough enabling the next renaissance. And now, we're building the infrastructure for the one that's coming.
We evolved our original icon to reflect this new chapter while honoring our foundation. The layered diamond structure tells the story:
The architecture echoes a central plaza—the Roman forum, the Greek agora, the English commons, the American town square—places where people gather, exchange ideas, build relationships, and shape culture. It's a fitting symbol for the infrastructure enabling the next leap in human coordination and creativity.
From the Mughal and Edo periods to the Flemish and Italian Renaissance, our brand imagery draws from different cultures and eras of extraordinary human flourishing—periods when science, commerce, culture and technology converged to create unprecedented leaps forward. These visuals reflect both the universal nature of the Renaissance and the global reach of our network.
But we're not just celebrating the past —we're creating the future: the infrastructure for humanity's next great creative and technological awakening, powered by privacy-native blockchain technology.
Join us to ask questions, learn more and dive into the lore.
Join Our Discord Town Hall. September 4th at 8 AM PT, then every Thursday at 7 AM PT. Come hear directly from our team, ask questions, and connect with other builders who are shaping the future of privacy-first applications.
Take your stance on privacy. Visit the privacy glyph generator to create your custom profile pic and build this new world with us.
Stay Connected. Visit the new website and to stay up-to-date on all things Noir and Aztec, make sure you’re following along on X.
The next renaissance is what you build on Aztec—and we can't wait to see what you'll create.
Aztec’s Public Testnet launched in May 2025.
Since then, we’ve been obsessively working toward our ultimate goal: launching the first fully decentralized privacy-preserving layer-2 (L2) network on Ethereum. This effort has involved a team of over 70 people, including world-renowned cryptographers and builders, with extensive collaboration from the Aztec community.
To make something private is one thing, but to also make it decentralized is another. Privacy is only half of the story. Every component of the Aztec Network will be decentralized from day one because decentralization is the foundation that allows privacy to be enforced by code, not by trust. This includes sequencers, which order and validate transactions, provers, which create privacy-preserving cryptographic proofs, and settlement on Ethereum, which finalizes transactions on the secure Ethereum mainnet to ensure trust and immutability.
Strong progress is being made by the community toward full decentralization. The Aztec Network now includes nearly 1,000 sequencers in its validator set, with 15,000 nodes spread across more than 50 countries on six continents. With this globally distributed network in place, the Aztec Network is ready for users to stress test and challenge its resilience.
We're now entering a new phase: the Adversarial Testnet. This stage will test the resilience of the Aztec Testnet and its decentralization mechanisms.
The Adversarial Testnet introduces two key features: slashing, which penalizes validators for malicious or negligent behavior in Proof-of-Stake (PoS) networks, and a fully decentralized governance mechanism for protocol upgrades.
This phase will also simulate network attacks to test its ability to recover independently, ensuring it could continue to operate even if the core team and servers disappeared (see more on Vitalik’s “walkaway test” here). It also opens the validator set to more people using ZKPassport, a private identity verification app, to verify their identity online.
The Aztec Network testnet is decentralized, run by a permissionless network of sequencers.
The slashing upgrade tests one of the most fundamental mechanisms for removing inactive or malicious sequencers from the validator set, an essential step toward strengthening decentralization.
Similar to Ethereum, on the Aztec Network, any inactive or malicious sequencers will be slashed and removed from the validator set. Sequencers will be able to slash any validator that makes no attestations for an entire epoch or proposes an invalid block.
Three slashes will result in being removed from the validator set. Sequencers may rejoin the validator set at any time after getting slashed; they just need to rejoin the queue.
In addition to testing network resilience when validators go offline and evaluating the slashing mechanisms, the Adversarial Testnet will also assess the robustness of the network’s decentralized governance during protocol upgrades.
Adversarial Testnet introduces changes to Aztec Network’s governance system.
Sequencers now have an even more central role, as they are the sole actors permitted to deposit assets into the Governance contract.
After the upgrade is defined and the proposed contracts are deployed, sequencers will vote on and implement the upgrade independently, without any involvement from Aztec Labs and/or the Aztec Foundation.
Starting today, you can join the Adversarial Testnet to help battle-test Aztec’s decentralization and security. Anyone can compete in six categories for a chance to win exclusive Aztec swag, be featured on the Aztec X account, and earn a DappNode. The six challenge categories include:
Performance will be tracked using Dashtec, a community-built dashboard that pulls data from publicly available sources. Dashtec displays a weighted score of your validator performance, which may be used to evaluate challenges and award prizes.
The dashboard offers detailed insights into sequencer performance through a stunning UI, allowing users to see exactly who is in the current validator set and providing a block-by-block view of every action taken by sequencers.
To join the validator set and start tracking your performance, click here. Join us on Thursday, July 31, 2025, at 4 pm CET on Discord for a Town Hall to hear more about the challenges and prizes. Who knows, we might even drop some alpha.
To stay up-to-date on all things Noir and Aztec, make sure you’re following along on X.
On May 1st, 2025, Aztec Public Testnet went live.
Within the first 24 hours, over 20k users visited the Aztec Playground and started to send transactions on testnet. Additionally, 10 apps launched live on the testnet, including wallets, block explorers, and private DeFi and NFT marketplaces. Launching a decentralized testnet poses significant challenges, and we’re proud that the network has continued to run despite high levels of congestion that led to slow block production for a period of time.
Around 6 hours after announcing the network launch, more than 150 sequencers had joined the validator set to sequence transactions and propose blocks for the network. 500+ additional full nodes were spun up by node operators participating in our Discord community. These sequencers were flooded with over 5k transactions before block production slowed. Let’s dive into why block production slowed down.
On Aztec, an epoch is a group of 32 blocks that are rolled up for settlement on Ethereum. Leading up to the slowdown of block production, there were entire epochs with full blocks (8 transactions, or 0.2TPS) in every slot. The sequencers were building blocks and absorbing the demand for blockspace from users of the Aztec playground, and there was a build up of 100s of pending transactions in sequencer mempools.
Issues arose when these transactions started to exceed the mempool size, which was configured to hold only 100mb or about 700 transactions.
As many new validators were brought through the funnel and started to come online, the mempools of existing validators (already full at 700 transactions) and new ones (at 0 transactions) diverged significantly. When earlier validators proposed blocks, newer validators didn't have the transactions and could not attest to blocks because the request/response protocol wasn't aggressive enough. When newer validators made proposals, earlier validators didn't have transactions (their mempools were full), so they could not attest to blocks.
New validators then started to build up pending transactions. When validators with full mempools requested missing transactions from peers, they would evict existing transactions from their mempools (mempool is at max memory) based on priority fee. All transactions had default fee settings, so validators were randomly ejecting transactions and were not doing so in lockstep (different validators ejected different transactions). For a little over an hour, the mempools diverged significantly from each other, and block production slowed down to about 20% of the expected rate.
In order to stop the mempool from ejecting transactions, the p2p mempool size was increased. By increasing the mempool size, the likelihood of needing to evict transactions that might soon appear in proposals is reduced. This increases the chances that sequencers already have the necessary transactions locally when they receive a block proposal. As a result, more validators are able to attest to proposals, allowing blocks to be finalized more reliably. Once blocks are included on L1, their transactions are evicted from the mempool. So over time, as more blocks are finalized and transactions are mined, the mempool naturally shrinks and the network will recover on its own.
If you are interested in running a sequencer node visit the sequencer page. Stay up-to-date on Noir and Aztec by following Noir and Aztec on X.
Kev Wedderburn is the father, architect, and team lead of Noir, a universal zero knowledge circuit writing language funded by Aztec Labs.
We're excited to bring you this interview and profile of the man and mystery behind the DSL creating a step-function change in the accessibility of ZK programs.
Alyssa: Hey Kev! Thanks so much for your time, I’d love to give readers a snapshot of your journey into web3 and Aztec Labs, as well as your focus on the Noir team.
Kev: Sure! Let’s jump in.
Alyssa: Can you start by sharing your web2 background?
Kev: Yes. I started out as a front-end developer, then moved into app development.
I built a social media site for books. Then, a janky music-sharing app that would check your playlist, then check my playlist, then if our playlists overlapped enough, it would recommend each of us songs on each other's playlist (this was before Spotify became Spotify I think).
Alyssa: How’d app development lead you to going full-time web3?
Kev: While transitioning to crypto, I made a tax app that scanned your bitcoin QR code and told you how much tax you owed.
From there, I started doing tutorial videos focused on smart contracts. I wanted to do one for a particular blockchain, and it turned out that they didn’t have a well-functioning wallet. So that’s actually what led to my entry into the web3 space. I didn’t end up finishing that tutorial, I just went on to build the wallet myself.
Alyssa: And this work led to your first formal web3 role?
Kev: Eventually, yes. While I was working on an improved wallet, I noticed the node that the original wallet was interacting with wasn’t that great either. So once the new wallet was finished, I moved on to creating a node in Golang (the wallet was also originally built in Golang).
After I finished the node, I got recruited by a privacy-focused project. And they asked me to build a node for their privacy network.
Once I dug deeper, it turned out they didn’t have a proving system. So then I started learning cryptography to implement a type of ZK proof called bulletproofs — state of the art at the time.
Alyssa: And you’ve primarily worked on privacy within web3 ever since, is that right?
Kev: Yes, I worked for several other privacy blockchains prior to Aztec, such as Monero. At Monero, I pivoted from implementing Bulletproofs to Plonk for increased proving speed, but noticed it was very challenging to program on top of Plonk.
The Plonk constraint system and proving system both have nice properties, but the UX was really bad. So Kobi Gurkan from Geometry Research, and Barry Whitehat from the Ethereum Foundation asked if I wanted to make a compiler — I guess they saw that I was pretty active within Plonk and cryptography in general.
Alyssa: Had you built one before?
Kev: At the time, I didn’t know much about compilers at all, so it was exciting to figure out what the compiler I’d build would look like, what other compilers were doing, and how to make a compiler with the safety guarantees needed for zero knowledge proofs.
That was the beginning of what we now call Noir, and I’ve been at Aztec since.
Alyssa: Wow, okay, so you’ve been with the Noir project since the beginning of Noir’s existence?
Kev: Yeah, exactly.
Alyssa: Amazing, congrats on all the progress you and the team have made. And what about getting into web3 in the first place? Was it through engineering, or your own interest in cryptocurrency? How did that look?
Kev: I first looked at Bitcoin in university, but was deterred by the codebase being challenging to read. But I wanted to learn Bitcoin and teach people about it. Back then, everything was a bit scammy. I even created a Bitcoin book…
Alyssa: Going back to Noir, how do you feel about the experience of learning the language you helped build? Is it intuitive for developers?
Kev: I can tend to over-criticize the things I do. But Noir’s in a solid place. There’s not much to really compare it to….there are other zkDSLs, but they give different guarantees for the most part. For example, Noir provides devs with a high-level language that aims not to sacrifice performance and safety, while Circom gives devs very little safety but allows them to do anything. There are pros and cons to both of these approaches.
The more control you give to a developer, the more powerful things they can do, but they can also easily make mistakes because the compiler is no longer holding your hand or stopping you from doing something potentially dangerous.
But yes, Noir is in a good place for developers to use. There’s still a lot we want to put into the language to make it comparable to common programming languages in terms of UX. But we’re well on our way.
Alyssa: And what about just being on the Aztec Labs team in general, and maybe even the Noir team within Aztec Labs? What’s that like? What do you enjoy about it?
Kev: The Aztec team is cross-functional and fluid, meaning that even though you’re on the Noir team, or the tooling team, or the engineering team, you can touch other parts of the stack. So that’s great about being at Aztec.
The fun thing about the Noir team in particular is that there are so many challenges we have yet to solve. We’ve solved quite a lot of them, but there’s still a lot we’re excited to work on like continuing to improve the UX, as I mentioned.
Alyssa: Love that answer as I know there’s a job opening on the Noir team, so someone joining can have exposure beyond understanding their specific role.
Kev: In fact, we encourage that, if you’re on tooling and you want to create something and the compiler just doesn’t seem to be fit to do what you want, feel free to start some print or tasks to modify the compiler. We’re always open to new ideas.
Alyssa: Really cool, that’s great. And what about beyond web3, any general interests or hobbies?
Kev: Generally speaking, I really like maths. I also used to sing and play guitar for quite a while, and I exercise a lot these days.
Alyssa: Thanks again for the chat, great learning a bit more about your work, Kev!
Kev: Thank you!
We think Noir has the best syntax, most modularity, and best ecosystem of any ZK language. But don't take our word for it.
Get started with Noir at noir-lang.org.
Today Aztec Labs is proud to announce that Aztec’s core circuits have been rewritten in Noir.
Aztec’s core circuits were previously written in C++. The circuits spanning private execution, public execution, and proof recursion are now in Noir. We didn’t undertake this decision lightly, but we made the call based on a single fact:
It was always our goal to achieve Aztec-Noir alignment, unifying our cryptography stack and making our code safer, simpler, and easier to audit.
We’re there now, in the era of unabashed Noir maximalism.
💻 You can find the open Noir circuit repos here.
The Noir circuits are merged and passing Aztec’s stringent protocol test suite–huge achievement for Noir as a language.
Writing your code in a domain-specific language (DSL) does not make it safer than writing it in a library.This may not be apparent – a DSL is just a language made for a specific problem. One could create a DSL that makes writing circuits easier, but does not improve on performance. One could even create one that makes writing circuits harder, but it’s very performant. Noir makes writing circuits easier and safer than our cpp library with little sacrifice to performance.
As a startup you want to be able to write code fast, but also safely. If you take too long to ship, you may just die. If you write code that is unsafe or brittle, you may lose the trust of your target audience.
We could say that all developers need to do better. Skill issue. However, this approach doesn’t scale beyond. Developers love to write smart, elegant, clever code, i.e. code that’s subject to bugs. In Noir, you need to opt into writing unsafe code.
So what’s wrong with using Barretenberg as a C++ library?
Nothing.
In fact, a library inherits a lot of adoption from its host language; a Solidity library can be picked up quickly by Solidity developers, for example.
Aztec’s constraint system library is written in C++, and while this allows developers to do anything they want, it also allows developers to do anything they want.
Developers need to be aware of quirks with C++ whenever they use Barretenberg. This can lead to subtle bugs due to the inherent compounding of quirks specific to C++ and quirks specific to the library. In other words, more gotchas or footguns.
Library writers also need to be careful because in some places they are reasoning about constraints. In other places, they are reasoning about unconstrained code or non-constraint system code.
The overarching problem here is that in order to write safe circuits, you need to be able to write C++ code and also be a good circuit writer. These are two different skill sets that Noir reduces to one because Noir is specifically designed as a circuit writing language.
In March, a team of cryptography engineers developed Aztec’s core cryptography circuits under the guidance of Aztec Labs CEO Zac Williamson. Developing in C++ required significant onboarding and technical overhead, including:
In the meantime, the Noir team has built a comprehensive toolchain that makes ZK development significantly smoother:
In addition to developer tooling like performance profiling, syntax highlighting, and auto-formatting.
With Noir, we built the fast and safe DevEx we wanted for ourselves, resulting in a full rewrite of all Aztec core circuits from C++ to Noir in less than a month of three engineers’ time.
Here’s a side-by-side code snippet comparison of our private kernelbase rollup circuit in C++ and Noir, highlighting the legibility and simplicity of Noir.
C++:
Noir:
Finally, Aztec Labs gets to more fully participate in Noir’s vibrant ecosystem.
The community continues to develop new tooling that improves code analysis. Developers building in the Noir ecosystem and discovering bugs continuously battle-test the compiler. And Aztec is now fully aligned with the many developers building applications and protocols on Noir.
We too would like to share in the fruits of the Noir community.
Noir maximalism is open-source maximalism.
While Noir is still Beta software and isn’t fully production-ready until it is audited, the language is progressing towards an implementation freeze by the first half of 2024, and a completed audit by the back half of the year.
🏗️ Start building with Noir at noir-lang.org.
In addition to basic optimizations required for the kernel circuit to run on low-powered mobile devices, we intend on integrating Noir with the arsenal of novel cryptography in our development pipeline:
Building Aztec in Noir has been a long time coming.
As a result of adapting our core circuits to Noir, testing a wide array of features, and having Noir code pass extensive test suites, we have dramatically more confidence in its stability.
The collaborative approach between our internal Aztec and Noir teams demonstrates a commitment to advancing the capabilities of zero-knowledge proof technologies in an integrated fashion.
Improving Noir now improves Aztec.
The truth of the matter is: you cannot escape potentially dangerous code.
You can still write unsafe code in Noir.
You can only move the responsibility of writing dangerous code to folks who are least likely to make a mistake. And with Noir, you make it Aztec Labs engineers’ responsibility to write compiler code and optimizations. And with our stack, we make it the cryptographers’ responsibility to write absolutely unhinged cryptographic proving systems.
You are free to rebuild all of this yourself in C++. But Noir makes it so you don’t need to.
Where we cannot help you is unsafe business logic. If your application was meant to choose a random number between 1 and 10 and it instead chooses a random number between 0 and 1, then that’s on you.
But that’s as it should be! That’s the sort of code that you should be responsible for, and Noir aims to make it such that that’s the only thing you are responsible for.
If that sounds good to you, you might consider making the switch, as we have.
⭐ Get started with Noir today at noir-lang.org.
Today we’re releasing NoirJS– a Javascript package for Noir developers who want to build real applications that generate zero knowledge proofs in the browser.
Web development within the Noir ecosystem has historically been, uhm, complex. Practically, that meant Noir developers couldn’t really build applications that ran in the browser. And we want people to build applications with our software!
A browser is an application used to access the World Wide Web and interact with Internet applications. It turns out most people like using browsers.
Before today, Noir didn’t really let you build applications that could run in-browser. Instead, developers were forced to run applications locally in a CLI.
In simple terms, that meant Noir couldn’t actually support real applications.
But now Noir does support applications with NoirJS.
The goals of NoirJS are simple:
Noir is a zero knowledge circuit-writing language that works with multiple crypto proving back-ends. That means the front-end (the language) remains the same but Noir can be modularized to support the latest and greatest in zero knowledge proving research.
We do this through the ACIR (abstract circuit intermediate representation). Learn more about the ACIR here.
NoirJS lets developers build around the core concept of client-side compute: the ability to harness user hardware–phones, laptops, tablets–through the browser in order to compute proofs of execution.
And client-side compute in turn allows for fully private and trustless blockchain systems.
…sound familiar??
That’s the core philosophy of Aztec–giving developers the tools to develop programs with private data and compute while remaining fully trustless.
In English: do blockchain things without anyone knowing! Cool, right?
And for developers’ convenience, NoirJS is packaged with Barretenberg–the same Plonkish backend used by Aztec Labs in the Aztec rollup. No need to go shopping for a proving system unless you like, really want to.
NoirJS does a lot of other things, too! Developers were previously burdened by the need to manage multiple components like `bb.js`, `acvm`, `noirc_abi`, and future components like `noir_wasm`.
But managing component libraries and balancing version compatibility is not our idea of fun.
To install NoirJS you simply run `npm i @noir-lang/noir_js` in your Javascript directory
Install your proving backend of choice (ahem, probably Barretenberg), and you’re good to go.
NoirJS handles all Noir dependencies, exposing them through one clean interface, allowing you to focus on building rather than fiddling with packages.
Here are some other advantages:
Immediate Access: Browser-based applications don’t require additional software, making it easier for developers to reach a wider audience.
Improved User Experience: By enabling Noir functionality in the browser, users can interact with applications in real-time. That means fast apps.
Enhanced Security: Operating in the browser allows for client-side cryptography, offering an additional layer of security for applications that require cryptographic proofs.
Developer Flexibility: NoirJS enables developers to build rich, client-side applications with cryptographic functions, providing a broader toolkit for web development.
Community Building: Browser-based Noir enables rapid prototyping and sharing among the developer community. This is especially useful for teams who focus on in-browser applications and use-cases.
In-Browser Tooling: NoirJS fits seamlessly with in-browser IDEs like VSCode for web, allowing for a streamlined development process in which Noir programs can be compiled and proven directly in the browser.
So to summarize, by bringing Noir to the browser, we’re:
Siiick.
Less development pain means more time for building new applications. Here are some use-cases we’re excited to see:
NoirJS lets you build real Noir applications that run in the browser. It also makes your life easy breezy beautiful CoverGirl.
If you don’t know what Noir is, read this announcement, scan these docs, and watch this video.
If you do know what Noir is, install NoirJS right now. Right now. Right now.
And if you end up building something cool, come ask us for money.
When we compute a ZK circuit we are not just executing some code, but proving that we have executed the code correctly.
Take a program that computes x + y = z. It’s not enough for a ZK program to simply output z, the program also needs to prove that x + y was executed correctly to arrive at the value z.
Producing the proof requires establishing constraints.
In other words, circuits are comprised of constrained functions–meaning ZK programs that generate proofs based on a set of constraints.
So why then, would you need a function with no constraints–an unconstrained function? You might think unconstrained functions would be unsafe, given their name–like taking the guardrails off of a ZK circuit. And you’d be right!
Circuit code without constraints can be “proven” to create any outcome! Rather than creating a proof that deterministically proves the validity of a piece of code, unconstrained functions allow you to execute code that would otherwise be very expensive or difficult to compute inside the circuit.
But being able to execute logic outside of a circuit is critical for both circuit performance and constructing proofs on information that is external to a circuit.
Generally, we want to use unconstrained functions whenever there's something that's easy to verify but hard to compute within the circuit.
An unconstrained function simply executes code as you would expect in a normal programming execution environment.
In this post we want to make sure that developers who are tapping into the performance benefits of unconstrained functions aren’t incorrectly implementing unconstrained functions in a way that leads to worse security for their programs. Incorrect usage of unconstrained functions could lead to bugs, and zk development overall is a newer, scarier paradigm. We want to make it easy for developers to use Noir to write performant and secure ZK programs, and unconstrained functions can help them optimize their circuits when implemented correctly.
Assuming proving divisions in ZK is costly while proving multiplications is easy, and we want to prove the computation of 100 / 5.
Proving 100 / 5 = x directly in ZK would be inefficient:
Instead, we might use unconstrained functions to optimize our circuits. A more optimized approach would involve:
1. Computing 100 / 5 = x in an unconstrained manner
2. Proving x * 5 = 100 in ZK
Here’s a way to optimize the same division operation:
Cautious readers however might notice both the code excerpts above yield approximately the same number of constraints in Noir’s abstract circuit intermediate representation (ACIR) given the optimization is simple enough to implement in Noir’s compiler.
The key intuition here is that in a ZK execution environment, proving multiplications is cheaper than proving divisions.
Given all Noir programs compile to an intermediate representation called the Abstract Circuit Intermediate Representation (ACIR), we can judge circuit optimization on both ACIR opcodes and the ultimate number of backend circuit gates.
This simple division case has 2 ACIR opcodes and 7 final backend circuit gates. The unoptimized version where we check assert(x == 20) has 3 ACIR opcodes and 8 final backend circuit sizes. Our optimization reduced the final backend size by one gate. Given this is a super simple example, let’s dive into a more complex case where the optimizations are more meaningful.
Colin Nielsen, developer in the Noir community wrote the following code for converting unsigned integers (uints) to u8 arrays, without the use of unconstrained functions.
👀 See Colin's Twitter + Github
Here's the unoptimized code:
This code has 91 total ACIR opcodes and a circuit size of 3,619. A lot of the operations in this function are already optimized away by the compiler (e.g., all the bitshifts turn into divisions by constants).
However, we can save a bunch of gates by casting to u8 a bit earlier. This automatically truncates the bitshifted value to fit in a u8, which allows us to remove the XOR against 0xff.
This is what the slightly-optimized code looks like:
ACIR opcodes generated: 75
Backend circuit size: 3,143
Already, this saves us ~480 gates in total, but we can do better.
This code is all constrained, so we're proving every step of the calculation using num. But in fact, we don't actually care about how we make the calculation, just that the computation is correct.
This is where unconstrained functions come in.
It turns out that truncating a u72 into a u8 is hard to do inside of a SNARK. Each time we do this operation to truncate down into u8, we lay down 4 ACIR opcodes, which get converted into multiple gates.
It's actually much easier to calculate num from out, rather than the other way around. All we need to do is multiply each element of out by a constant and add them all together, both of which are relatively easy operations to do inside of a SNARK.
So, instead of truncating u72 into u8, we can run u72_to_u8 as unconstrained function code in order to calculate out. Then, we can use that result in our constrained function and assert that if we were to do the reverse calculation, we'd get back num.
An example of what this looks like is below:
Total ACIR opcodes generated: 78
Backend circuit size: 2,902
This usage of unconstrained functions ends up optimizing our circuit even further and taking off another ~250 gates from our circuit!
We've ended up with more ACIR opcodes than before, but these are easier for the backend to prove (resulting in fewer gates overall). This is the beauty of using unconstrained functions – optimizing code that’s easy to verify but hard to compute within the circuit.
Put differently, unconstrained functions allow you to reformulate certain pieces of code that are easier to check than to execute directly in a ZK circuit.
Resources
For more on unconstrained functions, see this post by Tom French in the official Noir docs: https://noir-lang.org/docs/noir/concepts/unconstrained
Are you a developer interested in getting started with Noir?
Jump into the noir-starter Github repo and when you’re ready apply for a Grant–we’re currently supporting Noir use-cases through the end of 2023.
