Aztec Network
26 Apr
## min read

Layer Cake: A guide to Layer 2s

Navigate the complexities of layer 2 solutions with Aztec's comprehensive guide, demystifying blockchain technology layers.

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Written by
Zac Williamson
Edited by

Hello!

I’m Zac, the CEO of Aztec. We’re the inventors of the Plonk universal ZK-SNARK and zk.money, the world’s first private rollup and one of the new layer 2 protocols that have recently been deployed to Ethereum.

The layer 2 landscape is becoming a truly fascinating place to explore as multiple teams have been converting vision into reality and deploying their tech to the Ethereum mainnet.

It’s also a bit of a minefield to navigate if you’re not plugged into the ecosystem and can work your way through the jargon.

Unfortunately, most people in a position to explain layer 2s have skin in the game and have some biases towards certain technologies (i.e. the ones their protocol uses!).

So what makes me different? Absolutely nothing! But at least I’ll tell you that upfront instead of pretending to be impartial, eh?

Still, I’ll do my best to give you a balanced overview. The world of blockchain-based cryptography/scaling is a small one and the teams that are pushing the boundaries all deserve respect for what they do. So I guess we should get into it!

What is a layer 2 and why are they important?

The transaction throughput of Eth 1.0 is limited which has led to extremely high transaction costs.The main cost of Eth transactions come from:

  • Cost of storage changes
  • Cost of transaction data
  • Cost of computation

Layer 2s delegate one or more of the above to a secondary network running on top of Ethereum.There are traditionally two categories of layer 2’s each with its own security requirements and trade-offs: optimistic rollups and zk rollups. Aztec is defining the third category, private rollups.

Optimistic Rollups

An optimistic rollup acts much like a miniature version of the Ethereum blockchain. It acts as its own network that hosts smart contracts and transactions.

Periodically, the optimistic rollup will broadcast transaction blocks to a layer 1 smart contract. The ‘blocks’ contains the complete transaction data of every transaction in the block, but nothing else. The layer 1 smart contract does not perform any computation or make any storage updates. This massively reduces the cost of publishing a block.

These rollups are ‘optimistic’ because they assume that every transaction is correct by default — they are not checked directly by a layer 1 smart contract.

Instead, if a user thinks a transaction is incorrect (e.g. double-spending), they can post a “fraud-proof”. The layer 1 smart contract can use the rollup’s published block data to validate the correctness of the alleged fraudulent transaction.

This is very expensive but only has to be done when bad behavior is suspected.

If bad behavior is discovered, the entity that published the optimistic rollup block (typically called a validator) loses some cryptocurrency they have staked.

Optimistic rollups rely on this economic consensus to ensure transactions are correct.

Withdrawal times from optimistic rollups are typically long (e.g. 1 week). This is because once a transaction has been published, one must wait to see if anybody alleges bad behavior and posts one of these fraud proofs (this is a bit like the awkward silence part in a wedding when the priest says “if anybody objects…”)

Waiting for fraud proofs drastically slows withdrawal times

The main cost of transactions on an optimistic rollup comes from the cost of publishing transaction data on-chain. This data availability problem is shared by all rollups, optimistic or otherwise. In order to prevent funds from being frozen, users need access to all of the rollup’s transaction data. Either it gets published onto layer 1, or extra trust assumptions are required (e.g. trust that some sidechain will make this data available).

At the time of writing, if the rollup does not publish its transaction data on-chain this implies that you are relying on a centralized service to not freeze your funds.

Pros:

  • Feature-rich. Can copy Eth 1.0 architecture and support smart contract
  • Easier to build and deploy vs zk-rollups

Cons:

  • Slow exit times. Need to wait ~1 week between tx execution and tx considered ‘safe’ due to the lack of a fraud-proof
  • Slow exit times can be mitigated with underwriters (entities that allow instant withdrawals by taking a small fee in lieu of risk…)

ZK Rollups

Computation and storage handled by a secondary network.

L2 broadcasts transaction data to mainnet along with a proof of correctness. A mathematical proof that the transactions are correct. i.e. the L2 transactions are rolled up into a single mega-transaction that is broadcast to a L1 smart contract.

The ‘zk’ in zk rollups stands for ‘zero knowledge’. However, zk rollups are not private — all transactions are public by default like optimistic rollups. The ‘zk’ comes from the fact that the proof of correctness is typically produced by a zero-knowledge proving system (e.g. a ZK-SNARK or a ZK-STARK).

The upside to this is that the cost of storage updates and computation is removed from Ethereum. There is no need to optimistically assume the transactions are correct, if the proof is valid you can know that the transactions are correct.

This means that withdrawal times are much faster vs optimistic rollups and fewer trust assumptions are required.

The white elephant in the room is that zero-knowledge proofs add a massive computational overhead to a transaction.

Creating a zero-knowledge proof of a computation is approximately 1,000,000 times slower than running the computation directly! This is a rough estimation that will vary depending on the computation in question, but is accurate for the types of computations found in Solidity smart contracts.

ZK rollups handle this by delegating proof construction to third parties with a lot of computing resources, “rollup providers”. Users will be dependent on these third-party services to create transactions for them. Rollup providers can censor or front-run transactions, much like Ethereum miners. The more computing power required, the fewer rollup providers are likely to be available, so the censorship problem must be adequately handled by the protocol architecture.

This computation overhead presents problems when it comes to porting smart contracts to the L2. Full EVM compatibility is the goal, but this 1,000,000 factor slowdown must be handled. The EVM is extremely SNARK-unfriendly because of its 256-bit word size and native support for SHA3 and other SNARK-unfriendly hashing algorithms. Even delegating proof computation to a third party with significant computation resources is likely insufficient. One possible solution is etching zkSNARK prover algorithms directly into silicon via FPGAs or ASICs. Rollup providers will require this hardware to construct proofs.

ZK proof construction is much slower than running a normal program. Our Plonk and Plookup research has sped up SNARKs by over an order of magnitude, but ZK-rollups still have performance problems compared to optimistic rollups.

Typically, SNARK and STARK programming languages have to accommodate the inefficiencies of the underlying proving system. Typically these languages have difficulties implementing variable-length loops and dynamic memory access (think dynamic arrays and vectors). Our latest Plookup research mitigates some of these problems, but not all of them.

This means that the zk rollup may require developers to port their contracts into a custom language (e.g. Starkware’s Cairo).

For zk rollups that do not aim for full EVM compatibility, one upside is cheaper transactions. Without needing to conform to EVM semantics, it is possible to reduce the amount of data broadcast per basic transaction. The Hermes network is an example of such a rollup.

Pros:

  • Possibly cheaper transactions than optimistic rollups
  • No need for fraud proofs, very fast withdrawal times

Cons:

  • Slower feature velocity than optimistic rollups
  • Dependent on third-party proof constructors with custom hardware
  • May require custom programming languages with limited features

Private Rollups

Aztec launched its private rollup on mainnet in March 2021. You can wrap your Eth in a privacy shield and make private transactions using our online privacy wallet zk.money.

Private rollups use similar tech to zk rollups but are a very different beast. The private rollup is architected to provide strong privacy guarantees to every user of the L2. Users hold their funds anonymously. When performing transactions, the sender and recipient are anonymous and the value being transferred is encrypted.

We use a state-of-the-art zero-knowledge proving system, Plonk, to do this. We invented Plonk in 2019 and it is rapidly becoming an industry-standard amongst teams using zero-knowledge proofs and building on blockchains.

Enabling privacy by design requires a radically different rollup architecture to a zk-rollup. We went with a privacy-first approach because we know that it is very difficult to retrofit programmable privacy onto a public L2 without damaging the user experience or requiring a drastic protocol re-architecture.

Current Ethereum-based privacy solutions are mixers. They can be used to anonymize a user’s holdings but little else. Our full vision for a private layer 2 encompasses much more:

  • Fully programmable private smart contracts. Private currencies can have advanced transaction logic
  • Private ownership of NFTs
  • NFTs with properties that are hidden to all but the owner
  • Anti-money-laundering and know-your-client checks can be programmed directly into private tokens/dApps (e.g. KYC tokens — you can trade with trusted counterparties without knowing their identity)
  • Private DeFi! This is a huge topic that deserves its own article (coming soon…)

This is only possible by architecting the protocol to put privacy first. The transaction and state models for the protocol must be designed to be compatible with privacy.

Pros

  • Transactions are private. User’s financial activity cannot be analyzed by third parties
  • Rollup providers cannot censor or front-run individual transactions. For the rollup provider, every tx looks like a list of random numbers
  • No need for fraud proofs, very fast withdrawal times
  • Users can unilaterally withdraw without assistance from a third party to perform computation

Cons

  • More expensive than public L2s (but cheaper than main-net), until data availability solutions/Eth 2.0 come online
  • Users must construct private transaction zk proofs locally. No delegating to a 3rd party. The zk-proving system must be lightning fast to achieve this
  • Slower feature velocity than a zk rollup or optimistic rollup due to client-side proof construction. Programmability can be achieved, but full EVM compatibility is a while off
  • The state model is different. The value must be represented in bitcoin-style UTXO ‘notes’ and not via Ethereum’s account model. This can be abstracted away at the application layer.

Sorting the signal from the noise

The L2 landscape is competitive and there is an enormous pressure to launch and gain users before one's competitors.

This can lead to corners being cut and additional trust assumptions being added, that are obscured from users.The biggest issue right now is that of data availability.

If the L2 does not publish its transaction data on-chain, the L2 controllers can freeze user’s funds.

Every team working on L2s is striving to push the boundaries of what is possible with today’s technology. While admirable, this makes it easy to hide protocol flaws in technical jargon.

If you’re thinking about using a layer 2, they should be able to adequately address the following questions:

  • How is the L2 approaching data availability? If their tx cost is <20x of a regular Eth transfer they might not be broadcasting everything on-chain
  • Can a user unilaterally withdraw from the L2 using only the information published on Ethereum?
  • Is there a public technical description of the protocol that third parties can validate?

In addition, for zk rollups and private rollups one should ask the following:

  • Is the on-chain data provably correct? Is all of it being fed into the rollup circuit as public inputs?
  • Is the L2 dependent on centralized compute clusters to create rollups? If so, what is their plan to prevent censorship and front-running? When fully decentralized, how many rollup providers will there likely be?
  • Are the proof construction algorithms publicly viewable and auditable?

The shape of what’s to come

The next 12 months are going to be a profoundly exciting time in the Layer 2 space. The myriad of protocols hitting mainnet is the culmination of years of deep R&D and engineering work from across the industry.

For Aztec’s private rollup, our focus is on pulling programmable private smart contracts into the world. Our flagship Plonk programming language, Noir, is designed to compile high-level programs into heavily optimized ZKSNARK circuits, ones that are fast enough for proof construction to happen in the browser. This tech will be the keystone to our Aztec 3.0 rollup architecture, which will support user-defined circuits created with Noir.

By combining programmable privacy with scaling, we’re adding the last missing link required for truly mainstream adoption of web3 technology. At last, web3 will be able to compete on a level playing field against traditional web2 tech, with strong privacy guarantees as standard. We want to foster a rich ecosystem of private cryptocurrencies and NFTs that interact in a privacy-preserving manner both with DeFi protocols and more traditional financial services.

We’ve demonstrated with zk.money that this is not some wild future tech. We’ve already developed the key technologies required to build this ambitious project, now we’re going to knuckle down and execute on our vision.

Read more
Aztec Network
Aztec Network
24 Sep
xx min read

Testnet Retro - 2.0.3 Network Upgrade

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.

What’s included in the upgrade? 

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. 

Feature highlights include: 

  • Improved node stability: The Aztec node software is now far more stable. Users will see far fewer crashes and increased performance in terms of attestations and blocks produced. This translates into a far better experience using testnet, as transactions get included much faster.
  • Boneh–Lynn–Shacham (BLS) keys: When a validator registers on the rollup, they also provide keys that allow BLS signature aggregation. This unlocks future optimizations where signatures can be combined via p2p communication, then verified on Ethereum, while proving that the signatures come from block proposers.
  • Low-memory proving mode: The client-side proving requirements have dropped dramatically from 3.7GB to 1.3GB through a new low-memory proving mode, enabling older mobile devices to send Aztec transactions and use apps like zkPassport. 
  • AVM performance: The Aztec Virtual Machine (AVM) performance has seen major improvements with constraint coverage jumping from 0% to approximately 90-95%, providing far more secure AVM proving and more realistic proving performance numbers from provers. 
  • Flexible key management: The system now supports flexible key management through keystores, multi-EOA support, and remote signers, eliminating the need to pass private keys through environment variables and representing a significant step toward institutional readiness. 
  • Redesigned slashing: Slashing has been redesigned to provide much better consensus guarantees. Further, the new configuration allows nodes not to penalize home stakers for short outages, such as 20-minute interruptions. 
  • Slashing Vetoer: The Slasher contract now has an explicit vetoer: an address that can prevent slashing. At Mainnet, the initial vetoer will be operated by an independent group of security researchers who will also provide security assessments on upgrades. This acts as a failsafe in the event that nodes are erroneously trying to slash other nodes due to a bug.

With these updates in place, we’re ready to test a feature-complete network. 

What happened after deployment? 

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. 

Initial block production 

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.

Block production stalled

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.

The Fix

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 restored

What’s Next

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. 

Attestation and Block Production rate on the new rollup

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.

Votes on slashing signals

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.

Noir
Noir
18 Sep
xx min read

Just write “if”: Why Payy left Halo2 for Noir

The TL;DR:

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.

Starting with Halo2

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:

  • Mobile proof generation with sub-second performance
  • Minimal proof sizes for transmission over weak mobile signals
  • Low memory footprint for on-device proving
  • Ethereum verifier for on-chain settlement

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.”

Bus factor = 1 😳

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."

Evaluating Noir: One day, in Argentina…

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."

Rebuilding (Ship of Theseus-ing) Payy

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."

Migration Time

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:

  • Rust core (According to Calum, "Writing a financial application in JavaScript is borderline irresponsible")
  • Three-proof system: client-side proof plus two aggregators  
  • Sparse Merkle tree with Poseidon hashing for state management

When things are transparent, they’re secure

"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.

Code Comparison

Halo2: Binary decomposition

  • Write a custom chip for binary decomposition
  • Implement constraint system manually
  • Handle grid placement and cell references
  • Manage witness generation separately
  • Debug at the circuit level when something goes wrong

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)

What's Next

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.

The Bottom Line

"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.

Aztec Network
Aztec Network
4 Sep
xx min read

A New Brand for a New Era of Aztec

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.

Behind the Brand: A New Mental Model

A brand is more than aesthetics—it's a mental model that makes Aztec's spirit tangible. 

Our Mission: Start a Renaissance

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.

Values Driving the Network

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. 

Visualizing the Next Renaissance

Just as our technology bridges different eras of cryptographic innovation, our new visual identity draws from multiple periods of human creativity and technological advancement. 

The Wordmark: Permissionless Party 

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.

  • The A channels the bold architecture of Renaissance calligraphy—when new printing technologies democratized knowledge. 
  • The Z strides confidently into the digital age with clean, screen-optimized serifs. 
  • The T reaches back to antiquity, imagined as carved stone that bridges ancient and modern. 
  • The E embraces the dot-matrix aesthetic of early computing—when machines first began talking to each other. 
  • And the C fuses Renaissance geometric principles with contemporary precision.

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.

The Icon: Layers of the Next Renaissance

We evolved our original icon to reflect this new chapter while honoring our foundation. The layered diamond structure tells the story:

  • Innermost layer: Sensitive data at the core
  • Black privacy layer: The network's native protection
  • Open third layer: Our permissionless builder community
  • Outermost layer: Mainstream adoption and real-world transformation

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.

Imagery: Global Genius 

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.

You’re Invited 

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.

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Aztec Network
Aztec Network
22 Jul
xx min read

Introducing the Adversarial Testnet

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.

Introducing the Adversarial Testnet

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.  

Slashing on the Aztec Network

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.

Decentralized Governance

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.

Start Your Plan of Attack  

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:

  • Homestaker Sentinel: Earn 1 Aztec Dappnode by maximizing attestation and proposal success rates and volumes, and actively participating in governance.
  • The Slash Priest: Awarded to the participant who most effectively detects and penalizes misbehaving validators or nodes, helping to maintain network security by identifying and “slashing” bad actors.
  • High Attester: Recognizes the participant with the highest accuracy and volume of valid attestations, ensuring reliable and secure consensus during the adversarial testnet.
  • Proposer Commander: Awarded to the participant who consistently creates the most successful and timely proposals, driving efficient consensus.
  • Meme Lord: Celebrates the creator of the most creative and viral meme that captures the spirit of the adversarial testnet.
  • Content Chronicler: Honors the participant who produces the most engaging and insightful content documenting the adversarial testnet experience.

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.