Aztec Network
20 Sep
## min read

Explaining the “Network” in Aztec Network

An in-depth look at the intricate network structure within the Aztec ecosystem, detailing its components and functionalities.

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Written by
Jon Wu
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A look into the pieces that comprise a private zkRollup

Aztec Network is a privacy-first zkRollup on Ethereum. Most people who are fans of Aztec understand the public nature of Ethereum and how Aztec serves to solve Ethereum’s drawbacks: privacy and scalability.

In this piece we want to underscore the elements of Aztec’s network architecture and offer a sense for how the different pieces work together to enable a privacy layer for Ethereum DeFi, DAOs, and NFTs.

It complements our more basic piece about how Aztec’s UTXO-based privacy architecture works, which can be found here.

As a guide to the anatomy of a transaction traversing Aztec’s network, we’ve supplied a handy dandy diagram:

User Transactions

It all starts with the most important element in the whole flow — a user making a private transaction.Typically the user interacts with a front-end (either the first-party maintained zk.money or an Ethereum app which has integrated the Aztec Connect SDK).User accounts are accessed and managed by the Aztec Connect SDK, and like Ethereum are comprised of public and private keys. Unlike Ethereum, however, Aztec accounts have a single public key but two types of private key: viewing keys and a spending keys.

The viewing key allows the holder to view a user’s owned encrypted notes think of this like a pair of decoder glasses that allows the holder to see a user’s note balances, but no one else’s:

The spending key on the other hand is like a key that allows the holder to unlock individual encrypted notes and spend them — either in a send, withdraw, or DeFi transaction.

You can register different spending keys to different devices, preventing the need to paste sensitive information across devices.

The Aztec SDK

The Aztec SDK manages all this through an easy-to-use API that allows developers to integrate account registration, recovery, and asset transfer functionality in a few lines.

The SDK retrieves encrypted state and presents it to the developer in a way that’s easy to serve to users, all while managing private information such that applications never have access.

When users grant applications access to their account, the SDK helps users spend funds, computing state updates with a proof of correctness. It manage state (what users own) and facilitates user transactions (updating state by constructing proofs).

In comparison, an Ethereum transaction is a request for a state update along with authorization from a private key (a signature). In Aztec, the SDK is itself computing the state update, and then sending the proof of correctness to an Aztec sequencer.

The sequencer is therefore not doing any real computation or state update but just offering a compression service — aggregating user proofs (“inner proofs”) into a larger single outer proof.

It’s worth noting also that the sequencer cannot reasonably discriminate between transactions, since all it receives is an encrypted proof of correctness for an underlying transaction, which is generated client-side in the user’s browser. This makes targeted censorship of specific transactions essentially impossible.

➡️ Learn more about building with Aztec with our SDK documentation

Falafel: the Aztec Client

Once the transaction is created, it’s sent to Falafel. Falafel is a Typescript implementation of Aztec’s client — think of it like Go Ethereum (geth) or any other Ethereum client that forms an interface between the user and the actual blockchain.

Falafel is offchain software that accepts user proofs (encrypted transactions), aggregates them, creates a rollup proof, and then sends rollup proofs to the rollup contract for validation. This large proof comprised of many user transactions is what we call an “outer proof” (the inner proofs being the proofs containing each individual user transaction).

Falafel is just a batching mechanism that creates a big mega proof that adds all the inner proofs together proving that all the underlying state updates are valid.

Some note on privacy and censorship resistance in the network’s end state: the only reasonable censorship a sequencer can undertake is refusal to process blocks and attempting to interrupt network liveness.

If we analogize sequencers who run Falafel as mailmen, the only thing they can do is quit delivering the mail, but they can’t open specific letters and envelopes, nor can they reject letters in a targeted way because there is no revealing information.

Anyone can run the Falafel client and become a sequencer. The Aztec sequencer proposes blocks — sets of encrypted transactions.

Our goal is to have a network of sequencers run Falafel, processing and batching transactions for publication. Currently, though, Aztec serves as the sole network sequencer.

➡️️ Explore the Falafel repo here

Rollup Contract

Once the outer proof is constructed, it’s sent to the on-chain rollup contract, a smart contract published on Ethereum (you can find it at this address).

The outer proof sent to the rollup contract can contain a variety of encrypted user actions: withdrawals, deposits, new account registrations, or Aztec Connect bridge transactions.

The outer proof is sent to the rollup contract for validation and state updates. The rollup contract then runs through each user transaction and executes the necessary logic on Ethereum Layer 1.

Deposit: Users move funds to the Aztec rollup contract, which locks funds and then credits the user with an L2 representation of those funds once the rollup is published to Ethereum.

Withdrawal: Users indicate they want to send funds out of Aztec, the rollup contract confirms the value of the singular note the user is spending, nullifies internal Aztec funds, and sends its L1 funds to the specified withdrawal address.

DeFi interaction: the rollup contract calls out to an Aztec Connect Bridge Contract, which serves as an interface to Layer 1 smart contracts.Bridge contracts are all fundamentally structured as two-input, two-output swaps: the rollup contract sends 1–2 assets into an L1 protocol, and atomically receives 1–2 assets back (a synchronous bridge like a swap) or returns token assets back at a later date (an asynchronous bridge like a timed vault). In the next block, it subsequently generates a claim note for the user to claim the returned asset at a later date.

You can think of this structure like inputting A + B and getting C + D back, either now or later:

Virtual assets are an Aztec-specific representation of token positions that can’t immediately be returned to the rollup — think vault positions, fixed term positions, or anything else that is escrowed for redemption at a later date.

In all cases, smart contract logic stays on Layer 1. Users are interacting with Layer 1 liquidity and smart contracts — with no liquidity fragmentation or logic execution “on Aztec” whatsoever!Aztec Connect serves as a privacy-and-batching layer for the battle-tested contracts and liquidity on Ethereum.

Subsidy Contract

We recently made an upgrade to Aztec that allows any party to fund subsidies for bridge transactions. Subsidies are an important part of bootstrapping bridges on Aztec while user volume gets to critical mass.Take for an example a bridge that supports 50-unit transaction batches. Think of this like a bus with 50 seats, which only departs for its destination once the bus is full.On any given day, three things could happen:

  1. All 50 “seats” get filled — yay!
  2. Not all 50 seats get filled, and people wait for a whiiiile before the rest of the seats get filled
  3. Someone at some point gets sick of waiting and pays for the whole batch to go down to Ethereum and execute

The “someone” in scenario 3 could be an individual electing to pay for the number of seats remaining, OR it could be the bus service itself. Protocols who want the bridge to be performant even before bus seats are selling out can subsidize regular departures, ensuring timely performance.Previously, Aztec offered these subsidies to our partners by managing a subsidy balance within Falafel, Aztec Network’s client. We would use the multisig to manually top up Falafel’s subsidy balance on a bridge-contract to bridge-contract basis.Now, a contract has been deployed that allows any EOA or contract account to subsidize bridge contracts under a certain set of parameters:

  1. Bridge ID
  2. Subsidy amount committed
  3. Bridge contract backstop (how often to subsidize running of the bridge, e.g. “6 hour backstop” means if the bridge reaches 6 hours without inclusion in a block, it automatically calls the subsidy contract for funds and inclusion in the next block)

When the subsidy amount runs out based on the given parameters, the subsidy contract simply stops returning a subsidy.

Previously, subsidy funding happened completely offchain (partner sends funds to our multisig, we then send it from the multisig to Falafel). Partners would have to trust us to use the funds wisely, do the appropriate accounting within Falafel, and hold the funds. It also required interaction with the Aztec Core Team.

Now, the subsidy contract allows anyone to permissionlessly fund bridge contracts, regardless of author or origin. The network owns the subsidy, and any sequencer running Falafel can claim it. It’s a step toward Aztec Network’s decentralization plan, making each part of the network stand on its own from the Aztec Core Team.

➡️  Explore the subsidy contract here

Conclusion

With Aztec, privacy is a feature you can now add to any Ethereum contract — and now you know exactly how it works!We’re excited to see developers and users explore the full potential of Aztec’s privacy architecture.If you’re a developer, check out the following resources:

And jump into our Discord for questions on how Aztec works!

Explaining the “Network” in Aztec Network was originally published in Aztec on Medium, where people are continuing the conversation by highlighting and responding to this story.

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Aztec Network
Aztec Network
31 Mar
xx min read

Announcing the Alpha Network

Alpha is live: a fully feature-complete, privacy-first network. The infrastructure is in place, privacy is native to the protocol, and developers can now build truly private applications. 

Nine years ago, we set out to redesign blockchain for privacy. The goal: create a system institutions can adopt while giving users true control of their digital lives. Privacy band-aids are coming to Ethereum (someday), but it’s clear we need privacy now, and there’s an arms race underway to build it. Privacy is complex, it’s not a feature you can bolt-on as an afterthought. It demands a ground-up approach, deep tech stack integration, and complete decentralization.

In November 2025, the Aztec Ignition Chain went live as the first decentralized L2 on Ethereum, it’s the coordination layer that the execution layer sits on top of. The network is not operated by the Aztec Labs or the Aztec Foundation, it’s run by the community, making it the true backbone of Aztec. 

With the infrastructure in place and a unanimous community vote, the network enters Alpha. 

What is the Alpha Network?

Alpha is the first Layer 2 with a full execution environment for private smart contracts. All accounts, transactions, and the execution itself can be completely private. Developers can now choose what they want public and what they want to keep private while building with the three privacy pillars we have in place across data, identity, and compute.

These privacy pillars, which can be used individually or combined, break down into three core layers: 

  1. Data: The data you hold or send remains private, enabling use cases such as private transactions, RWAs, payments and stablecoins.
  2. Identity: Your identity remains private, enabling accounts that privately connect real world identities onchain, institutional compliance, or financial reporting where users selectively disclose information.
  3. Compute: The actions you take remain private, enabling applications in private finance, gaming, and beyond.

The Key Components  

Alpha is feature complete–meaning this is the only full-stack solution for adding privacy to your business or application. You build, and Aztec handles the cryptography under the hood. 

It’s Composable. Private-preserving contracts are not isolated; they can talk to each other and seamlessly blend both private and public state across contracts. Privacy can be preserved across contract calls for full callstack privacy. 

No backdoor access. Aztec is the only decentralized L2, and is launching as a fully decentralized rollup with a Layer 1 escape hatch.

It’s Compliant. Companies are missing out on the benefits of blockchains because transparent chains expose user data, while private networks protect it, but still offer fully customizable controls. Now they can build compliant apps that move value around the world instantly.

How Apps Work on Alpha 

  1. Write in Noir, a proprietary rust-like programming language for writing smart contracts. Build contracts with Aztec.nr and mark functions private or public.
  1. Prove on a device. Users execute private logic locally and a ZK proof is generated.
  1. Submit to Aztec. The proof goes to sequencers who validate without seeing the data. Any public aspects are then executed.
  1. Settle on Ethereum. Checkpoints batch proofs to L1 every ~12s. Ethereum verifies everything. 

Developers can explore our privacy primitives across data, identity, and compute and start building with them using the documentation here. Note that this is an early version of the network with known vulnerabilities, see this post for details. While this is the first iteration of the network, there will be several upgrades that secure and harden the network on our path to Beta. If you’d like to learn more about how you can integrate privacy into your project, reach out here

To hear directly from our Cofounders, join our live from Cannes Q&A on Tuesday, March 31st at 9:30 am ET. Follow us on X to get the latest updates from the Aztec Network.

Aztec Network
Aztec Network
27 Mar
xx min read

Critical Vulnerability in Alpha v4

On Wednesday 17 March 2026 our team discovered a new vulnerability in the Aztec Network. Following the analysis, the vulnerability has been confirmed as a critical vulnerability in accordance with our vulnerability matrix.

The vulnerability affects the proving system as a whole, and is not mitigated via public re-execution by the committee of validators. Exploitation can lead to severe disruption of the protocol and theft of user funds.

In accordance with our policy, fixes for the network will be packaged and distributed with the “v5” release of the network, currently planned for July 2026.

The actual bug and corresponding patch will not be publicly disclosed until “v5.”

Aztec applications and portals bridging assets from Layer 1s should warn users about the security guarantees of Alpha, in particular, reminding users not to put in funds they are not willing to lose. Portals or applications may add additional security measures or training wheels specific to their application or use case.

State of Alpha security

We will shortly establish a bug tracker to show the number and severity of bugs known to us in v4. The tracker will be updated as audits and security researchers discover issues. Each new alpha release will get its own tracker. This will allow developers and users to judge for themselves how they are willing to use the network, and we will use the tracker as a primary determinant for whether the network is ready for a "Beta" label.

Additional bug disclosure

We have identified a vulnerability in barretenberg allowing inclusion of incorrect proofs in the Aztec Network mempool, and ask all nodes to upgrade to versions v.4.1.2 or later.

We’d like to thank Consensys Diligence & TU Vienna for a recent discovery of a separate vulnerability in barretenberg categorized as medium for the network and critical for Noir:

We have published a fixed version of barretenberg.

We’d also like to thank Plainshift AI for discovery, reproduction, and reporting of one more vulnerability in the Aztec Network and their ongoing work to help secure the network.

Aztec Network
Aztec Network
18 Mar
xx min read

How Aztec Governance Works

Decentralization is not just a technical property of the Aztec Network, it is the governing principle. 

No single team, company, or individual controls how the network evolves. Upgrades are proposed in public, debated in the open, and approved by the people running the network. Decentralized sequencing, proving, and governance are hard-coded into the base protocol so that no central actor can unilaterally change the rules, censor transactions, or appropriate user value.

The governance framework that makes this possible has three moving parts: Aztec Improvement Proposal (AZIP), Aztec Upgrade Proposal (AZUP), and the onchain vote. Together, they form a pipeline that takes an idea to a live protocol change, with multiple independent checkpoints along the way.

The Virtual Town Square

Every upgrade starts with an AZIP. AZIPs are version-controlled design documents, publicly maintained on GitHub, modeled on the same EIP process that has governed Ethereum since its earliest days. Anyone is encouraged to suggest improvements to the Aztec Network protocol spec.

Before a formal proposal is opened, ideas live in GitHub Discussions, an open forum where the community can weigh in, challenge assumptions, and shape the direction of a proposal before it hardens into a spec. This is the virtual town square: the place where the network's future gets debated in public, not decided behind closed doors.

The AZIP framework is what decentralization looks like in practice. Multiple ideas can surface simultaneously, get stress-tested by the community, and the strongest ones naturally rise. Good arguments win, not titles or seniority. The process selects for quality discussion precisely because anyone can participate and everything is visible.

Once an AZIP is formalized as a pull request, it enters a structured lifecycle: Draft, Ready for Discussion, then Accepted or Rejected. Rejected AZIPs are not deleted — they remain permanently in the repository as a record of what was tried and why it was rejected. Nothing gets quietly buried.

Security Considerations are mandatory for all Core, Standard, and Economics AZIPs. Proposals without them cannot pass the Draft stage. Security is structural, not an afterthought.

From Proposal to Upgrade

Once Core Contributors, a merit-based and informal group of active protocol contributors, have reviewed an AZIP and approved it for inclusion, it gets bundled into an AZUP.

An AZUP takes everything an AZIP described and deploys it — a real smart contract, real onchain actions. Each AZUP includes a payload that encodes the exact onchain changes that will occur if the upgrade is approved. Anyone can inspect the payload on a block explorer and see precisely what will change before voting begins.

The payload then goes to sequencers for signaling. Sequencers are the backbone of the network. They propose blocks, attest to state, and serve as the first governance gate for any upgrade. A payload must accumulate enough signals from sequencers within a fixed round to advance. The people actually running the network have to express coordinated support before any change reaches a broader vote.

Once sequencers signal quorum, the proposal moves to tokenholders. Sequencers' staked voting power defaults to "yea" on proposals that came through the signaling path, meaning opposition must be active, not passive. Any sequencer or tokenholder who wants to vote against a proposal must explicitly re-delegate their stake before the voting snapshot is taken. The system rewards genuine engagement from all sides.

For a proposal to pass, it must meet quorum, a supermajority margin, and a minimum participation threshold, all three. If any condition is unmet, the proposal fails.

Built-In Delays, Built-In Safety

Even after a proposal passes, it does not execute immediately. A mandatory delay gives node operators time to deploy updated software, allows the community to perform final checks, and reduces the risk of sudden uncoordinated changes hitting the network. If the proposal is not executed within its grace period, it expires.

Failed AZUPs cannot be resubmitted. A new proposal must be created that directly addresses the feedback received. There is no way to simply retry and hope for a different result.

No Single Point of Control

The teams building the network have no special governance power. Sequencers, tokenholders, and Core Contributors are the governing actors, each playing a distinct and non-redundant role.

No single party can force or block an upgrade. Sequencers can withhold signals. Tokenholders can vote nay. Proposals not executed within the grace period expire on their own.

This is decentralization working as intended. The network upgrades not because a team decides it should, but because the people running it agree that it should.

If you want to help shape what Aztec becomes, the forum is open. The proposals are public. The town square is yours. 

Follow Aztec on X to stay up to date on the latest developments.

Aztec Network
Aztec Network
10 Mar
xx min read

Alpha Network Security: What to Expect

Aztec’s Approach to Security

Aztec is novel code — the bleeding edge of cryptography and blockchain technology. As the first decentralized L2 on Ethereum, Aztec is powered by a global network of sequencers and provers. Decentralization introduces some novel challenges in how security is addressed; there is no centralized sequencer to pause or a centralized entity who has power over the network. The rollout of the network reflects this, with distinct goals at each phase.

Ignition

Validate governance and decentralized block building work as intended on Ethereum Mainnet. 

Alpha

Enable transactions at 1TPS, ~6s block times and improve the security of the network via continual ongoing audits and bug bounty. New releases of the alpha network are expected regularly to address any security vulnerabilities. Please note, every alpha deployment is distinct and state is not migrated between Alpha releases. 

Beta

We will transition to Beta once the network scales to >10 TPS, with reduced block times while ensuring 99.9% uptime. Additionally, the transition requires no critical bugs disclosed via bug bounty in 3 months. State migrations across network releases can be considered.

TL;DR: The roadmap from Ignition to Alpha to Beta is designed to reflect the core team's growing confidence in the network's security.

This phased approach lets us balance ecosystem growth while building security confidence and steadily expanding the community of researchers and tools working to validate the network’s security, soundness and correctness.

Ultimately, time in production without an exploit is the most reliable indicator of how secure a codebase is.

At the start of Alpha, that confidence is still developing. The core team believes the network is secure enough to support early ecosystem use cases and handle small amounts of value. However this is experimental alpha software and users should not deposit more value than they are willing to lose. Apps may choose to limit deposit amounts to mitigate risk for users.

Audits are ongoing throughout Alpha, with the goal to achieve dual external audits across the entire codebase.

The table below shows current security and audit coverage at the time of writing.

The main bug bounty for the network is not yet live, other than for the non-cryptographic L1 smart contracts as audits are ongoing. We encourage security researchers to responsibly disclose findings in line with our security policy .

As the audits are still ongoing, we expect to discover vulnerabilities in various components. The fixes will be packaged and distributed with the “v5” release.

If we discover a Critical vulnerability in “v4” in accordance with the following severity matrix, which would require the change of verification keys to fix, we will first alert the portal operators to pause deposits and then post a message on the forum, stating that the rollup has a vulnerability.

Security of the Aztec Virtual Machine (AVM)

Aztec uses a hybrid execution model, handling private and public execution separately — and the security considerations differ between them.

As per the audit table above, it is clear that the Aztec Virtual Machine (AVM) has not yet completed its internal and external audits. This is intentional as all AVM execution is public, which allows it to benefit from a “Training Wheel” — the validator re-execution committee.

Every 72 seconds, a collection of newly proposed Aztec blocks are bundled into a "checkpoint" and submitted to L1. With each proposed checkpoint, a committee of 48 staking validators randomly selected from the entire set of validators (presently 3,959) re-execute all txs of all blocks in the checkpoint, and attest to the resulting state roots. 33 out of 48 attestations are required for the checkpoint proposal to be considered valid. The committee and the eventual zk proof must agree on the resultant state root for a checkpoint to be added to the proven chain. As a result, an attacker must control 33/48 of any given committee to exploit any bug in the AVM.

The only time the re-execution committee is not active is during the escape hatch, where the cost to propose a block is set at a level which attempts to quantify the security of the execution training wheel. For this version of the alpha network, this is set a 332M AZTEC, a figure intended to approximate the economic protection the committee normally provides, equivalent to roughly 19% of the un-staked circulating supply at the time of writing. Since the Aztec Foundation holds a significant portion of that supply, the effective threshold is considerably higher in practice.

Quantifying the cost of committee takeover attacks

A key design assumption is that just-in-time bribery of the sequencer committee is impractical and the only ****realistic attack vector is stake acquisition, not bribery.

Assuming a sequencer set size of 4,000 and a committee that rotates each epoch (~38.4mins) from the full sequencer set using a Fisher-Yates shuffle seeded by L1 RANDAO we can see the probability and amount of stake required in the table below.

To achieve a 99% probability of controlling at least one supermajority within 3 days, an attacker would need to control approximately 55.4% of the validator set - roughly 2,215 sequencers representing 443M AZTEC in stake. Assuming an exploit is successful their stake would likely de-value by 70-80%, resulting in an expected economic loss of approximately 332M AZTEC.

To achieve only a 0.5% probability of controlling at least one supermajority within 6 months, an attacker would need to control approximately 33.88% of the validator set.

What does this means for builders?

The practical effect of this training wheel is that the network can exist while there are known security issues with the AVM, as long as the value an attacker would gain from any potential exploit is less than the cost of acquiring 332M AZTEC.

The training wheel allows security researchers to spend more time on the private execution paths that don’t benefit from the training wheel and for the network to be deployed in an alpha version where security researchers can attempt to find additional AVM exploits.

In concrete terms, the training wheel means the Alpha network can reasonably secure value up to around 332M AZTEC (~$6.5M at the time of writing).

Ecosystem builders should keep the above limits in mind, particularly when designing portal contracts that bridge funds into the network.

Portals are the main way value will be bridged into the alpha network, and as a result are also the main target for any exploits. The design of portals can allow the network to secure far higher value. If a portal secures > 332M AZTEC and allows all of its funds to be taken in one withdrawal without any rate limits, delays or pause functionality then it is a target for an AVM exploit attack.

If a portal implements a maximum withdrawal per user, pause functionality or delays for larger withdrawals it becomes harder for an attacker to steal a large quantum of funds in one go.

Conclusion

The Aztec Alpha code is ready to go. The next step is for someone in the community to submit a governance proposal and for the network to vote on enabling transactions. This is decentralization working as intended.

Once live, Alpha will run at 1 TPS with roughly 6 second block times. Audits are still ongoing across several components, so keep deposits small and only put in what you're comfortable losing.

On the security side, a 48-validator re-execution committee provides the main protection during Alpha, requiring 33/48 consensus on every 72-second checkpoint. Successfully attacking the AVM would require controlling roughly 55% of the validator set at a cost of around 332M AZTEC, putting the practical security ceiling at approximately $6.5M.

Alpha is about growing the ecosystem, expanding the security of the network, and accumulating the one thing no audit can shortcut: time in production. This is the network maturing in exactly the way it was designed to as it progresses toward Beta.