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Inside Aztec

Inside
Aztec

purple_2
Aztec Network
31 Mar
xx min read

Announcing the Alpha Network

The First Feature Complete Privacy Stack is Here

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.

Most Recent
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
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
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.

Aztec Network
4 Mar
xx min read

Aztec Network: Roadmap Update

The Ignition Chain launched late last year, as the first fully decentralized L2 on Ethereum– a huge milestone for decentralized networks. The team has reinvented what true programmable privacy means, building the execution model from the ground up— combining the programmability of Ethereum with the privacy of Zcash in a single execution environment.

Since then, the network has been running with zero downtime with 3,500+ sequencers and 50+ provers across five continents. With the infrastructure now in place, the network is fully in the hands of the community, and the culmination of the past 8 years of work is now converging. 

Major upgrades have landed across four tracks: the execution layer, the proving system, the programming language, Noir, and the decentralization stack. Together, these milestones deliver on Aztec’s original promise, a system where developers can write fully programmable smart contracts with customizable privacy.

The infrastructure is in place. The code is ready. And we’re ready to ship. 

What’s New on the Roadmap?

The Execution Layer

The execution layer delivers on Aztec's core promise: fully programmable, privacy-preserving smart contracts on Ethereum. 

A complete dual state model is now in place–with both private and public state. Private functions execute client-side in the Private Execution Environment (PXE), running directly in the user's browser and generating zero-knowledge proofs locally, so that private data never leaves the original device. Public functions execute on the Aztec Virtual Machine (AVM) on the network side. 

Aztec.js is now live, giving developers a full SDK for managing accounts and interacting with contracts. Native account abstraction has been implemented, meaning every account is a smart contract with customizable authentication rules. Note discovery has been solved through a tagging mechanism, allowing recipients to efficiently query for relevant notes without downloading and decrypting everything on the network.

Contract standards are underway, with the Wonderland team delivering AIP-20 for tokens and AIP-721 for NFTs, along with escrow contracts and logic libraries, providing the production-ready building blocks for the Alpha Network. 

The Proving System

The proving system is what makes Aztec's privacy guarantees real, and it has deep roots.

In 2019, Aztec's cofounder Zac Williamson and Chief Scientist Ariel Gabizon introduced PLONK, which became one of the most widely used proving systems in zero-knowledge cryptography. Since then, Aztec's cryptographic backend, Barretenberg, has evolved through multiple generations, each facilitating faster, lighter, and more efficient proving than the last. The latest innovation, CHONK (Client-side Highly Optimized ploNK), is purpose-built for proving on phones and browsers and is what powers proof generation for the Alpha Network.

CHONK is a major leap forward for the user experience, dramatically reducing the memory and time required to generate proofs on consumer devices. It leverages best-in-class circuit primitives, a HyperNova-style folding scheme for efficiently processing chains of private function calls, and Goblin, a hyper-efficient purpose-built recursion acceleration scheme. The result is that private transactions can be proven on the devices people actually use, not just powerful servers.

This matters because privacy on Aztec means proofs are generated on the user's own device, keeping private data private. If proving is too slow or too resource-intensive, privacy becomes impractical. CHONK makes it practical.

Decentralization

Decentralization is what makes Aztec's privacy guarantees credible. Without it, a central operator could censor transactions, introduce backdoors, or compromise user privacy at will. 

Aztec addressed this by hardcoding decentralized sequencing, proving, and governance directly into the base protocol. The Ignition Chain has proven the stability of this consensus layer, maintaining zero downtime with over 3,500 sequencers and 50+ provers running across five continents. Aztec Labs and the Aztec Foundation run no sequencers and do not participate in governance.

Noir

Noir 1.0 is nearing completion, bringing a stable, production-grade language within reach. Aztec's own protocol circuits have been entirely rewritten in Noir, meaning the language is already battle-tested at the deepest layer of the stack. 

Internal and external audits of the compiler and toolchain are progressing in parallel, and security tooling including fuzzers and bytecode parsers is nearly finished. A stable, audited language means application teams can build on Alpha with confidence that the foundation beneath them won't shift.

What Comes Next

The code for Alpha Network, a functionally complete and raw version of the network, is ready.

The Alpha Network brings fully programmable, privacy-preserving smart contracts to Ethereum for the first time. It's the culmination of years of parallel work across the four tracks in the Aztec Roadmap. Together, they enable efficient client-side proofs that power customizable smart contracts, letting users choose exactly what stays private and what goes public. 

No other project in the space is close to shipping this. 

The code is written. The network is running. All the pieces are in place. The governance proposal is now live on the forum and open for discussion. Read through it, ask questions, poke holes, and help shape the path forward. 

Once the community is aligned, the proposal moves to a vote. This is how a decentralized network upgrades. Not by a team pushing a button, but by the people running it.

Programmable privacy will unlock a renaissance in onchain adoption. Real-world applications are coming and institutions are paying attention. Alpha represents the culmination of eight years of intense work to deliver privacy on Ethereum. 

Now it needs to be battle-tested in the wild. 

View the updated product roadmap here and join us on Thursday, March 5th, at 3 pm UTC on X to hear more about the most recent updates to our product roadmap.

Explore by Topic
Vision
Vision
20 Aug
xx min read

Renowned Cryptographer and Coauthor of PLONK, Ariel Gabizon Rejoins Aztec Labs as Chief Scientist

Ariel Gabizon, a distinguished cryptographer, coauthor of PLONK, and pioneer of zero-knowledge (ZK) technology, has rejoined Aztec Labs as its Chief Scientist.

Ariel brings over 14 years of experience in mathematics and has played a key role in major advancements in ZK technology. He began with a PhD in Theoretical Computer Science from the Weizmann Institute. During his postdoctoral tenure, a serendipitous encounter with the Bitcoin whitepaper ignited his passion for applied cryptography.

This led him to join Eli Ben-Sasson's lab, where he made significant contributions to the early development of STARKs when they were known as probabilistically checkable proofs (PCPs). He was involved in the first deployment of ZK technology at Zcash and coauthored two pivotal papers that made SNARK setups practical and viable.

In addition to his groundbreaking work on the PLONK paper, co-authored with Zachary Williamson, Ariel also helped discover a crucial counterfeiting vulnerability stemming from the underlying zk-SNARK originally used by Zcash. Since then, he has been advancing the state of the art in polynomial commitment schemes (SHPLONK, FFLONK), lookup protocols (Plookup,cq) and folding schemes (ProtoGalaxy).

With Devnet now live and private, client-side smart contract execution with public verifiability possible, Ariel is rejoining us at a pivotal moment for Aztec, our upcoming privacy-first L2 on Ethereum. His expertise and vision will be vital in continuing to drive our efforts to build a more private, secure, and efficient blockchain ecosystem. As Chief Scientist, Ariel will spearhead our research and development efforts, focusing on enhancing the privacy and scalability of Aztec. Ariel’s expertise will not only bolster our existing work but pave the way for innovative advancements in ZK technology. You can read more about the work Ariel is doing at Aztec via his recently published paper, Private Proofs of Stack and Contract Execution Using Protogalaxy.

Ariel is speaking at the Verifiable Summit during Warsaw Blockchain Week on September 4th, 2024. This event will provide a platform for Ariel to discuss recent progress on Fast Fourier Transforms from the Galois FFT and circle STARK papers. Get your discounted ticket using FRENSOFAZTEC.

We are confident that Ariel’s experience and expertise in mathematics, cryptography and ZK technology will propel us to new heights. We invite our community to follow us on X for regular updates.

Aztec Network
Aztec Network
13 Aug
xx min read

Devnet Goes Live: Introducing Alpha Build with $100K in Prizes

Devnet is now live! This milestone enables private, client-side smart contract execution with robust public verifiability, a massive milestone for Aztec and the Ethereum community.

To celebrate this milestone, we’re launching Alpha Build, a series of three developer sprints with a USD $100,000 prize pool and the opportunity to deploy on the Aztec Network for the first time.

The first Alpha Build will kick off Monday, August 19th with two additional Alpha Builds happening by mid-November. Alpha Build participants will receive expert mentorship, gain direct access to the team, and connect with a growing community of over 300 developers from around the globe. In addition to cash prizes, top builders will be invited to deploy their applications on the Devnet.

Complete the Alpha Build Application to gain access to the Discord server, and download the Aztec Sandbox to get started.

How Did We Get Here?

Devnet is a culmination of all the hard work and iteration over the past 7 years. 

In March 2023, we made a bold commitment to focus on bringing the Aztec Network to life and delivering true programmable privacy. Over the past year and a half, our team has worked tirelessly to bring this vision to life, and their efforts have paid off. 

Today, we’re proud to deliver on that commitment and unveil a live Devnet, realizing the integration of all essential components of the tech stack, including Honk, cutting-edge cryptography, Noir for smart contract development, a private execution environment (PXE) for client-side proof generation, and a sequencer for transaction processing and public execution. 

Together, they enable private, client-side smart contract execution with robust public verifiability, marking a significant leap forward for the Aztec Network.

More on Alpha Build   

Over the next few months, we’ll run three themed Alpha Builds with challenges across the most important use cases in crypto, including payments, gaming, and identity. Privacy expands the design space so you can explore solutions for conditional payments, on and off-chain access control using NFTs stored privately on Aztec, or card games with a shared hidden public state.

The three challenges for Alpha Build One (ab1) will focus on payment use cases with an emphasis on building a UI, Account Abstraction and Fee Abstraction features. If you’re new to Aztec or have been with us from the beginning, ab1 is your chance to dive deep into underexplored problems and designs while contributing to the growing ecosystem. 

Complete the Alpha Build Application to gain access to the Discord server, and download the Aztec Sandbox to get started.

ab1 Challenge Overview

The Alpha Build payment challenges are designed to build upon each other, increasing in complexity as the weeks progress. Here’s what you can expect:

  1. Challenge #1: Wallet
    • Develop an interface similar to Daimo/Payy that uses secp256r1 signature verification, similar to FaceID or TouchID.
    • Build a web interface to facilitate smooth user interaction with Aztec.
  2. Challenge #2: Programmable Accounts
    • Create custom account contracts with alternative authorization methods than simple digital signatures.
    • Integrate transaction authorization through zkemail.
    • Implement features for spending limits or a multisig account contract.
  3. Challenge #3: Programmable Fee
    • Design a system to sponsor transaction fees on behalf of users.
    • Develop a Paymaster capable of handling payments in multiple tokens.

Throughout the challenges, the DevRel Team will provide Discord support and host weekly office hours from 10 a.m. - 11 a.m. ET every Wednesday and Thursday. 

Submission Criteria

All submissions for ab1 are due by Sunday, September 15th, 2024, and must include the following: 

  • A link to the GitHub repo of your project 
  • A README file that describes how to run and use the applications and or contracts 
  • X handle
  • Telegram
  • Discord username

Let’s Create the Future of Payments, Together  

Don’t miss this opportunity to deploy on the Aztec Network for the first time. 

To get started, fill out the Alpha Build Application. We will review applications and, if selected, invite you to join a private Discord channel for our Alpha Build. 

The Devnet Live Celebration will be on Friday, August 16th, 2024, at 11:30 a.m. ET on X. Join Cat, our Developer Relations Engineer, and President and Co-Founder, Joe Andrews as they dive deep into Alpha Build season, exploring challenges, themes, and innovative ideas. 

Research
Research
8 Aug
xx min read

Does zero-knowledge provide privacy?

Intro

In blockchain narrative, the term “zero knowledge” entered our vocabulary when rollups first emerged. In particular, we’ve heard it a lot in the context of zero knowledge rollups (ZK-rollups). But, zero knowledge technology has existed for years before. The first article on zero knowledge was published back in 1989.

In this blog, we’ll break it down to clarify what zero knowledge (ZK) is and what it ISN’T (the latter might actually be more interesting than the former). We’ll investigate if ZK-rollups have any ZK for real, and if not, why they get to use the term at all, and dive into the difference between ZK as a technology and ZK as a marketing term.

For those who need answers right away:

  • ZK-rollup provides a succinct verification mechanism
  • But ZK-rollup does NOT provide privacy

*by privacy we mean (i) user privacy (transaction sender and recipient), (ii) data privacy (payload of the transaction, e.g., the asset or value being transacted), and (iii) code privacy (the program logic).

Now let’s dive a bit deeper.

Zero Knowledge Property Outside of Rollups

If we want to discuss ZK in a rollup context, we first need to understand zero knowledge property on its own. As we mentioned above, the concept of ZK was introduced in 1989 (years before the first blockchain was baked) in a paper titled, “The knowledge complexity of interactive proof systems.” It wasn’t until around 2018 that the Ethereum community figured out ZK might be a good fit for a rollup universe.

We usually consider zero knowledge as a property of a proving system. In blockchain, we often say ZKP, meaning zero knowledge proof. But “proof” might mean proof of statement or proof of knowledge. So, in the next section of this article, we will differentiate between the two types of proofs.

Proof of Statement

Proof of statement proves that a statement is true without revealing anything about the statement itself.

Examples of statements:

  • z is a square modular n: z = x^2 mod n
  • The graphs G and H are non-isomorphic
  • The number 638634389........3427 has 3 prime factors

Proof of Knowledge

Proof of knowledge proves that the person making an assertion has some knowledge about the statement.

So, if we look at the examples from the previous paragraph side-by-side:

Proof of StatementProof of Knowledgez is a square modular n: z = x^2 mod n.I know a value x such that z = x^2 (mod n).The graphs G and H are non-isomorphic.I know the isomorphism between two graphs, G and H.The number 638634389........3427 has 3 prime factors.I know the factors of the number 638634389........3427.

One should note that every proof of knowledge is a proof of statement (but not the opposite). For instance, if one proves that they know a value x such that z = x^2 (mod n), this will be proof of knowledge, but it also automatically proves that z is a square modulo n (proof of statement).

Let’s explore one of these examples to see how proof of statement and proof of knowledge can be constructed!

Exploring Examples: the Graph-Isomorphism Problem

Let’s use the graph-isomorphism problem. To do this, we’ll say proof of graph non-isomorphism will be proof of statement, while a proof of graph isomorphism will be proof of knowledge.

What Is the Graph-Isomorphism Problem?

Basically graph isomorphism (denoted by ≅) is the following: two graphs with labeled nodes are isomorphic if they are "the same" up to a permutation of the labels. That is to say, there exists a permutation of the labels of one graph that results in the other graph.

More formally, we say that two graphs G and H are isomorphic if there is a bijective function f between the vertices’ labels of G and H such that there is an edge between the vertices u and v in G if and only if there is an edge between the vertices f(u) and f(v) in H.

An example of two isomorphic graphs:

Source

If there exists no such permutation, we say that the two graphs are non-isomorphic. Now, assume we want to prove that two graphs are non-isomorphic. We only want to prove this single fact; nothing about the graphs themselves, no other knowledge except for the statement that they are non-isomorphic.

Example of A Proof of statement: the Graph-Non-Isomorphism Problem

Proof intuition:

  • If there are two non-isomorphic graphs G and H, one randomly chooses a permutation π (re-orders elements in a deterministic way) as well as randomly chooses one of two graphs, and calculates K = π{G or H} that is K is a permutation of either G or H.
  • If G and H were isomorphic, anyone else should NOT be able to tell from which of the two graphs K was computed, and could only guess.
  • The probability of guessing would be ½. Repeating the protocol enough times makes the probability of guessing negligible.

One round of protocol:

Example of A Proof of Knowledge: Graph Isomorphism

Now, let’s think… What if we want to prove two graphs are isomorphic? In other words, the Prover wants to prove that they know the isomorphism σ such that H = σ(G).

Proof intuition:

  • If σ is an isomorphism between two graphs, it means that H = σ(G) and G = σ^{-1}(H) where σ^{-1} is the reverse isomorphism.
  • Let π be a permutation randomly chosen by the Prover. Using ρ = πσ^{-c} (where the Verifier randomly assigns 0 or 1 to c), they get either  ρ = π or ρ = πσ^{-1}.
  • By applying ρ = π to a graph, one will get its permutation. By applying  ρ = πσ^{-1} to a graph, one will get its permuted reverse isomorphism:

One round of protocol:

Back to Zero Knowledge!

Now that we’ve explored examples of proof of statement and proof of knowledge, let’s discuss whether or not they have zero knowledge property.

Informally, zero knowledge means that a Verifier can’t retrieve any additional information from a Prover (except for the information clear from the proof itself).

In the example of graph isomorphism, proof of knowledge is zero knowledge (with honest Verifier). According to the protocol, the Prover doesn’t reveal any information on the isomorphism or permutation to the Verifier. Instead, they send the Verifier commitments and that’s it.

However, in the example of the proof of graph non-isomorphism, it’s not zero knowledge. Because, instead of setting K = π(G) or K = π(H), a malicious Verifier (i.e. a Verifier which deviates from the protocol) can set K = π{RANDOM GRAPH} and as a result of the protocol execution by the Prover, the Verifier will know if RANDOM_GRAPH is isomorphic to either G or H. So the Verifier is definitely able to retrieve additional information.

Can we convert our proof of graph non-isomorphism into zero knowledge? Yes, we can. The Verifier should also provide proof that (i) the graph it sends is isomorphic either to G or to H (meaning the graph they’re sending is not arbitrary), and (ii) they know the isomorphism.

One should note that most protocols in the space are only honest-verifier ZK (i.e. ZK property doesn’t hold with malicious verifier). However, this isn’t an issue because the protocols are made non-interactive with the Fiat-Shamir heuristic. Hence – there is no distinction for non-interactive protocols as the verifier cannot "misbehave.”

Now, when we differentiated between proof of statement and proof of knowledge and saw that both of them can have zero knowledge property or not have it, let’s take a look at ZK-rollup and figure out (i) does it use proof of statement or proof of knowledge, (ii) does it have zero knowledge property?

Finally, Back to ZK-Rollups!

In a ZK-rollups, the logic is pretty similar to the graph-non-isomorphism problem (where we prove the statement that two graphs are non-isomorphic). In ZK-rollup, we prove the statement that the state transition was done correctly.

A Glimpse into How ZK-Rollups Work

In this section, we’ll briefly cover how ZK-rollups work and how they utilize proofs. By “ZK-rollups,'' we mean regular (i.e. NON-privacy-preserving) ZK-rollups such as Scroll, Starknet, zksync, Taiko, and many more.

The main use of “vanilla” ZK-rollups is to enable scalability by posting a single proof of the validity of transactions.

ZK-rollups execute transactions off-chain and post proof on L1 (Ethereum) that whatever they did off-chain was done correctly. Their purpose is to prove that the new chain state is correct.

To generate a proof of correct state transition, one needs to prove that all transactions were executed correctly on given inputs.

For the sake of this, the Prover needs to know previous state and input values.

However, for the Verifier to verify the proof, they need to have the proof as well as to know new state, previous state, and input values:

Inputs

There are two types of inputs, public and private. In ZK-rollups, “private input” does NOT mean “secret” even though they are called “private.” Instead, it means that private inputs are consumed by Prover only while public inputs are consumed both by Prover and Verifier (sometimes private inputs are also called “witness” as a reference to the NP complexity class). Public inputs are expensive as they need to be submitted to L1 hence we want it to be as small (“succinct”) as possible. In terms of what these inputs consist of in the context of the proof:

Public inputs (consumed by Prover AND Verifier) – all data that needs to be submitted to L1 so that everyone can update their records of the current state. This will include new state root as well as might include signatures, sender, receiver, functions, contract addresses, function arguments, newly-deployed contract data, storage slots which have changed and their new values, events that were emitted. One should note that this reveals A LOT of information to a public observer. The specific list of public inputs will depend on the specific ZK-rollup design.

Private inputs (consumed by Prover ONLY) – all information that was needed by rollup circuits to prove correctness of the state transition. This will include Merkle membership proofs (hash paths) as well as the execution trace (might include transaction inputs such as newly-deployed contract data, storage slots which have changed and their new values, and events that were emitted).

As you can see from the logic above, private inputs have nothing to do with privacy. So if a ZK-rollup is generating a proof that Alice sent Bob 1ETH, both the Prover and the Verifier will be aware of this information (i.e. no privacy at all!).

To sum it up, in the case of a ZK-rollup, we want to prove the validity of transactions, it is a proof of statement and it does NOT have zero-knowledge property because all the information (i.e. state, functions, inputs) is public and everything that is not provided explicitly can be derived by a Verifier.

That is to say, there is no ZK in a vanilla ZK-rollup. Why is it called ZK-rollup then?

Maybe… For the sake of marketing =)

And Still, Can ZK Provide Privacy?

Short answer: yes, it can. While the main use of “vanilla” ZK-rollups is to enable scalability, the main use of Aztec is to enable scalability AND allow privacy. And, it utilizes ZK exactly for the privacy purpose.

Aztec provides privacy by means of client-side proof generation, i.e. whatever should be processed privately is processed on the user’s device and then a proof of its correct execution is supplied to the mempool.

Processed privately means that

  • Transactions are processed privately (on user’s device)
  • Their outputs shroud side effects (such as note hashes and nullifiers)
  • And those get added to the global state without revealing any information to anyone except for (i) the client who executed transactions and emitted side effects, and (ii) the receiver of side effects (for example, in case of a transfer from Alice to Bob, Alice executes transactions client-side and emits side effects and Bob receives side effects).

Client-side proofs are then verified by the sequencer (who manages the mempool).

In this case, client-side proof is a zero knowledge proof of statement: the sequencer verifies the proof validity without any information about what was executed on the client-side, and is unable to retrieve any information about it.

After client-side proofs have been verified by the sequencer, everything is similar to a vanilla ZK-rollup mechanism as described in the previous section. That is to say, Aztec ZK-rollup first generates a number of client-side proofs (which are zero knowledge proofs) and then a block proof (which is not zero knowledge).

One Can’t Just Add ZK to Get Privacy

It’s not possible to add privacy ad-hoc to an already existing ZK-rollup. It should be designed to be private from the very beginning.

One first needs to give a precise definition of “privacy” as the statements proved, depending on the rollup design, may reveal unnecessary information and harm user privacy.

If builders want their dApps to interact with the external world; meaning that dApps aren’t monolithically private but instead allow some functions and variables to be private while some functions and variables stay public (e.g. necessary for AMMs, lending protocols, etc.), rollup state management becomes very non-trivial. Now it has to process public and private state updates separately. However, it’s exactly the latter approach that unlocks dozens of use cases we’ve been dreaming about for years! (Think programmable on-chain identity management and DeFi alternatives to conservative financial institutions).

As of today, Aztec is one of very few privacy-preserving L2s on Ethereum where privacy is provided by processing private information on the client-side. Check out this article to dive into client-side proof generation and this article to learn more about Aztec smart contracts anatomy allowing for hybrid private and public state management.

Ready to join Aztec’s building pioneers? Let us know by filling out this form.

Many thanks to Palla, Patrick, and Brecht for review.

Noir
Noir
8 Aug
xx min read

Unlocking the Future of Privacy: Join the Noir Research Campaign for Provable Emails

In the ever-evolving landscape of digital privacy, the power of Zero-Knowledge Proofs (ZKPs) is revolutionizing how we protect and prove information. Noir, a leading language for privacy-first programmable privacy, is at the forefront of this innovation and is calling on you to help us enhance provable emails using Noir. This research campaign (NCR#1), running from August 8th - 25th, 2024 presents a unique opportunity to push the boundaries of privacy while creating novel solutions for secure email verification.

Why Privacy-First, Provable Emails?

The rise of Programmable Cryptography and Zero-Knowledge Proofs offers unprecedented potential for trustless and private verification of information, cryptographically bridging data across silos. Imagine a world where you can prove ownership of an email address or an email received without revealing its content or personal details. This capability is not just a theoretical possibility, but a practical reality waiting to be unlocked through advanced research and development.

What We’re Looking For

Aztec Labs has been a strong supporter of this vision, particularly with the ZK Email team's pioneering work. As a part of these continued efforts, we invite researchers, developers, tech enthusiasts, and anyone with creative ideas to propose a two-month research plan that explores ways to leverage Noir (and Aztec) to augment this work and its broader vision.

We’re looking for proposals focused on building end-user-oriented projects, including MVPs. Proposals focused on building developer tooling and technical/cryptography research are also welcome as long as their relevance to zkEmail is clear.

Multiple submissions are welcomed, however, to be considered, your proposal must meet the following criteria:

  • Implementation in Noir: Your final implementation should include components written in Noir, if not fully in Noir.
  • Testing and Documentation: Ensure thorough testing and comprehensive documentation of your implementation.
  • Open Source: The final implementation must be open-sourced under a permissive license (e.g., MIT).

How to Submit Your Proposal

To participate, please head to our GitHub and submit your proposal using the following format:

  • Title
  • Summary
  • Methodology
  • Timeline and Deliverables
  • Team
  • Start Date
  • Questions

Proposal submissions are open now and will close on August 25th, 2024. Our selection committee will pick two proposals that will receive up to US$40,000 in grants. Winners will be announced before September 5th, 2024, via GitHub Discussions and X.

Click here to get started on your proposal today.

Audit Partners

We believe in the value of the real-world impact of top-tier research.

To ensure the security and quality of applying research outcomes, we’re onboarding audit partners to sponsor and provide auditing for the final implementations of selected proposals. Potential audit partners will be evaluated up to August 20th, 2024, and announced on GitHub by August 31st, 2024.

To learn more about how to get involved, please contact Savio or Lisa.

Start Tinkering

Join us in pioneering the future of privacy-first communication. Submit your proposal and be part of this transformative journey with Noir!