Aztec Network
May 19th, 2019
## min read

Creating, Settling & Streaming Confidential Assets

This is the fourth part, we dive into the creation and management of confidential assets, a breakthrough in private transactions.

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Written by
Joe Andrews
Edited by

This article is in English, you can read a Mandarin(中文) translation here.

This series is split into 4 parts:

  • Part 1 — An introduction to AZTEC
  • Part 2 — Deploying AZTEC on Ganache
  • Part 3 — Constructing Proofs, Signing Flows and Key Management
  • Part 4 — Creating, Settling, & Streaming Confidential Assets

The demo dApp implements a confidential loan on Ethereum. The loan provides for the following functionality :

  1. A borrower can create a loan request with a confidential loan notional.
  2. A lender can request access to see the value of the loan notional.
  3. A lender can settle a loan request by transferring the notional to the borrower, the transfer notional should be confidential. The blockchain should verify that the notional amount and the settlement amount are equal.
  4. The borrower should be able to pay interest into an account that the lender can withdraw from. Any payments to the interest account should be confidential.
  5. The lender should be able to withdraw interest from the interest account as it accrues up to the last block time. The blockchain should verify the amount of interest the lender is withdrawing is correct, and the withdraw amount and the balance of the account should remain confidential.
  6. The lender should be able to mark a loan as defaulting if the interest account does not contain sufficient interest. The blockchain should validate that this is the case whilst keeping the total interest payed, the account balance and the loan’s notional confidential.
  7. The borrower should be able to repay the loan and any outstanding accrued interest at maturity. Both the interest and the notional repayment should remain confidential.

To build the above functionality, the dApp will combine two confidential assets, and the following proofs: Mint Proof, Join Split Proof, Bilateral Swap Proof, Dividend Proof, Private Range Proof.

Creating the Loan ZkAsset

As the loan is intended to be a fully private asset without a public equivalent, it will inherit from the reference EIP1724ZkAssetMintable.sol contract. In this case, the constructor is overridden with to create a fully private asset.

pragma solidity >= 0.5.0 <0.7.0;import "@aztec/protocol/contracts/ERC1724/ZkAssetMintable.sol";import "@aztec/protocol/contracts/libs/NoteUtils.sol";import "@aztec/protocol/contracts/interfaces/IZkAsset.sol";contract Loan is ZkAssetMintable {  using NoteUtils for bytes;constructor(    address _aceAddress,   ) public ZkAssetMintable(_aceAddress, address(0), 1, true, false)          {  } }

All AZTEC toolkits perform logical checks on note values. To perform a logical check, a note must first be created. In order for the loan’s notional to be confidential, it must be represented as a note in the loan’s note registry. As the initial supply of any note registry is zero, in a private asset the Mint Proof must be used to adjust the total supply and create new notes.

Step 1: Constructing the Mint Proof

Firstly, construct a proof using aztec.js.

const {   proofData,} = aztec.proof.mint.encodeMintTransaction({        newTotalMinted: newTotalNote,        oldTotalMinted: oldTotalNote,        adjustedNotes: [loanNotionalNote],        senderAddress: loanDappContract.address,});

Step 2

This proof can now be used to Mint the new notes inside the loan’s note registry. Only the owner of the note registry is permitted to call the confidentialMintmethod. In this case, a smart contract called the constructor of the loan ZkAsset. That contract is the owner of the ZkAsset note registry. This permits it to validate a supplied proof and process the resultant transfer instructions inside ACE.

Loan(loanId).confidentialMint(MINT_PROOF, bytes(_proofData));

The Settlement ZkAsset

The primary functions of the loan (primary settlement, interest payments and repayment) require value transfer. As this value transfer is required to be confidential, the settlement asset also needs to be a ZkAsset that implements EIP1724. The ZkAsset represents the currency the loan counter-parties will use to transact and is redeemable for a public ERC20 token e.g (DAI, CUSD).

Creating the settlement asset requires initialising the ZkAsset constructor with different parameters to the Loan ZkAsset. This tells ACE that this asset is linked to a public ERC20 token and the supply is not adjustable.

pragma solidity >= 0.5.0 <0.7.0;import "@aztec/protocol/contracts/ERC1724/ZkAsset.sol";contract ZKERC20 is ZkAsset {constructor(    address _aceAddress,    address _erc20Address   ) public ZkAsset(_aceAddress, address(_erc20Address), 1, false, true) {  }}

Creating an AZTEC note in the note registry of the Settlement ZkAsset requires a transfer of sufficient ERC20 tokens into ACE equal to the notes value multiplied by a scaling factor. These tokens are owned by ACE in return for creating the desired note.

It is worth noting that creating notes of a ZkAsset with a linked public token has limited confidentiality. An observer of the blockchain can deduce the notes created in any given transaction, sum to the amount of ERC20 consumed. As such it is recommended to create multiple notes in one transaction, in order to help obfuscate the value of individual notes.

If full confidentiality is required for the settlement asset, a private ZkAsset with no public equivalent should be used. Here, AZTEC notes are issued on receipt of funds via bank transfer. The notes are still 1–1 backed with fiat, similar to a stable coin, but the note creation transaction preserves confidentiality as no public ERC20 tokens are consumed. Carbon Money are working on an implementation of this.

This demo assumes a fully private asset is not required and consuming ERC20 tokens is an acceptable solution.

Step 1:

The ACE contract is approved to spend ERC20 tokens on behalf of the token owner.

await settlementToken.approve(aceContract.address, value);

Step 2: Creating the proof

const {      proofData,      expectedOutput} = aztec.proof.joinSplit.encodeJoinSplitTransaction({    inputNotes: [],    outputNotes: [Note1, Note2], // note values sum to kPublic    senderAddress: account.address,    inputNoteOwners: [],    publicOwner: account.address,    kPublic: -value,     validatorAddress: joinSplitContract.address, });

A particular variant of the Join Split proof is required when interacting with public value. The proof has no inputNotes, the input is a public value of ERC20 represented by kPublic. This value is negative as it represents value being converted into an AZTEC note form, (if value was redeemed from note form, the value would be positive). The Join Split proof is validation that the sum of the output notes is equal to the value of kPublic.

The proof construction also requires the Ethereum addresses of the publicOwner (the owner of the tokens spent in this transaction) and the senderAddress (the account that will send this transaction to the ACE for validation), to be set.

Step 3: Approving ACE to spend Tokens

Any proof that results in the transfer of public value has to be first approved by the owner of the public tokens for it to be valid. This allows ACE to transfer the value of the tokens consumed in the proof and acts as an additional security measure when dealing with ERC20s.

await ACE.publicApprove(zkAsset.address, hashProof, kPublic, {      from: accounts[0],});

Step 4: Relaying the transaction

When relaying proofs to ACE, the sender address specified in the proof must match the msg.sender of the account that calls ACE.validateProof().This prevents malicious actors snooping on the transaction pool from front running the execution of this proof.

(bytes memory _proofOutputs) = ACE.validateProof(JOIN_SPLIT_PROOF, address(this), _proofData);

Step 5: Processing Transfer Instructions

Successful proof validation will return an array of proof outputs. These proof outputs contain the state update instructions that allow a dApp to update a note registry.

_loanVariables.settlementToken.confidentialTransferFrom(JOIN_SPLIT_PROOF, _proof2Outputs.get(0));

Settling the loan

Once the loan ZkAsset and the settlement ZkAsset have been created, and each note registry populated with the initial notes, the loan is prepared for settlement. The diagram below shows the state of our dApp at this point and the swap that is required for settlement

The left hand side represents the loan ownership register (currently owned by the borrower) and the right hand side represent all of the notes that make up the lenders balance of the settlement asset.

To settle the loan the Bilateral Swap Proof is required. The borrower wishes to receive a note of the settlement ZkAsset equal to the loans notional multiplied by the loan price. The lender wishes to receive a note that represents 100% of the loan’s ownership register, in this case the notional note. Later on, this note will be used to claim interest and repayment at maturity. The ownership note can also be split and transferred should the lender wish to trade the loan.

Step 1 : Approving the settlement contract to spend notes

As the settlement transaction needs to be atomic, the transaction will be orchestrated by a smart contract. After a proof has been validated, ACE will only process the state updates (create or destroy notes) if the notes destroyed in a transaction have first been approved for spending by the note owner. The validation and processing of the Bilateral Swap proof must occur in an atomic transaction, otherwise, if one side of a transaction fails to approve the notes for spending, there is a chance one party will not receive their required ask in the swap. It is up to the dApp developer to ensure the correct permission logic is in place when calling functions within the AZTEC system. ACE will only validate the mathematical logic of a transaction, but does not know if a transaction should take place. In the case of loan settlement, the dApp should validate that the input notes have been approved by both the buyer and the seller and they are agree to the transfer.

In order for the transaction to process correctly, both the borrower and the lender need to approve the settlement contract to spend their respective notes.

const settlementSignature = signNote(   zkSettlementAsset.address,   settlementNoteHash,   loanId,   lender.privateKey);await zkSettlementAsset.confidentialApprove(   settlementNoteHash,   loanId,   true,   settlementSignature,    {      from: lender.address,  });

Step 2: Constructing the proof

const {     proofData,} = aztec.proof.bilateralSwap.encodeBilateralSwapTransaction({        inputNotes: [takerBid, takerAsk],        outputNotes: [makerAsk, makerBid],        senderAddress: loanId,});

The proof requires 4 notes, and will validate the following logical statements:

  1. The takerBid note is equal to the makerAsk note.
  2. The takerAsk note is equal to the makerBid note.

Step 3: Relaying the Transaction and Updating State

When relaying proofs to ACE, the sender address specified in the proof must match the msg.sender of the account that calls ACE.validateProof().This prevents malicious actors snooping on the transaction pool from front running the execution of this proof.

Once validated, the proof outputs can be used to update the retrospective note registries. This will destroy the takerBid note and create the makerAsk note in the settlement ZkAsset note registry and destroy the makerBid note and create the takerAsk note in the loan ZkAsset note registry.

(bytes memory _proofOutputs) = ACE.validateProof(BILATERAL_SWAP_PROOF, address(this), _proofData);(bytes memory _loanProofOutputs) = _proofOutputs.get(0);(bytes memory _settlementProofOutputs) = _proofOutputs.get(1);settlementZkAsset.confidentialTransferFrom(BILATERAL_SWAP_PROOF, _settlementProofOutputs);loanZkAsset.confidentialTransferFrom(BILATERAL_SWAP_PROOF, _loanProofOutputs);

Thats it! The loan has been settled and all balances remain confidential.

Interest Streaming

AZTEC notes can be owned by smart contracts. This makes it is possible to construct complicated financial instruments using AZTEC. For the loan, we wish to create a system in which the lender can withdraw interest from an account as it accrues. Should the interest account contain insufficient collateral the lender should be able to mark the loan as defaulting and the smart contract transfer any security used as collateral to the lender.

To make interest streaming non-interactive from the borrowers point of view, the blockchain must validate the interest the lender is trying to withdraw is not greater than the currently accrued interest, and use this validation to ensure the correct amount of interest is then withdrawn. This flow is possible by combing the Dividend Proof and the Join Split proof. The Dividend Proof allows us to prove that one note is a ratio of another note plus a residual (to account for the quirks of solidity arithmetic).

Note1 * a = Note2 * b + Residual

If Note2 is set as the withdrawal note, the proof creator is incentivised to pick values of a and b such that the residual note is minimised. This enables Note2 to be expressed as a ratio of Note1 .

Note1 = Note2 * b/a

To apply this to the loan, a ratio must be found that expresses the AccruedInterest with respect to another note supplied by the smart contract in this case the notional.

This is possible with a little algebra:

Interest Steaming with the Dividend Proof

As a smart contract can set the values of ElapsedTime, InterestRate and InterestPeriod. The lender will only be able to construct a proof that will satisfy equation (1) if the value of AccruedInterest picked is correct up to the last block time.

If the Dividend Proof succeeds, the Accrued interest note that is used can be trusted and if supplied inside a subsequent valid Join Split proof, can be used to split the CurrentInterestBalance into the AccruedInterest plus a remainder note.

This process can be repeated for each block allowing the lender to withdraw interest as it accrues by the second. In each case, the blockchain will validate this correctness of the withdrawal.

#moneystreaming

Programatic Default — No Lawyers

Historically, should a borrower fail to pay interest on a loan or fail to pay back the loan at repayment, the lender would have to go through the courts to claim any collateral in lieu of repayment. Interest streaming allows the blockchain to validate a state of default and programatically transfer any collateral to the lender without the need for any arbitration, lawyers or courts.

To achieve this, two proofs are combined the Dividend Proof as used before to validate the currently accrued interest, and the Private Range Proof, to validate that the accrued interest is greater than the available balance inside the interest account.

Putting it all together — DEMO

https://medium.com/media/828f2ee46c391382128652e0eee2b481/href

The Loan dApp is available on github and can be cloned here.

Thanks for reading Part 4 of this series!

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Aztec Network
Aztec Network
7 Aug
xx min read

Alpha V5 Proving System Vulnerability

Status

Core contributors identified a critical vulnerability affecting the V5 Alpha proving system on 27 July 2026 through internal AI-assisted auditing.

V5 remains Alpha software. Critical findings can arise during this phase, and the audit process exists to identify them before broader deployment. This finding places V5 funds, applications, and contract state at risk.

Treat funds and applications on V5 as exposed to a protocol-level failure until contributors complete incident response work and operators carry out the required network actions.

What we are disclosing

An attacker may be able to exploit a flaw in the current V5 proving system by constructing a proof that passes verification for a transaction the network should reject. If accepted, that transaction could produce a state transition outside the rules V5 intends to enforce.

Contributors cannot determine whether anyone exploited the flaw before this finding. The affected system lacks the information needed to distinguish ordinary accepted transactions from transactions accepted through the flawed proving path. Historical chain activity cannot establish whether exploitation occurred or quantify its impact.

Application safeguards

We expect application teams to prepare safeguards in the coming weeks.

Those safeguards may include changes to application controls, deployment procedures, user flows, and migration plans. We expect each team to assess its contracts and determine which protections fit its architecture and users.

We expect teams planning a V5 deployment to pause that work until contributors publish further guidance. We expect teams with live contracts to review their ability to limit user exposure, isolate affected functionality, and move users to fresh deployments if needed.

We expect applications that maintain administrative or emergency controls to assess whether those controls can reduce user risk during the incident timeframe.

Next steps

Core contributors are working with operators, application teams, and bridge operators as applications add security guards around affected flows.

The findings from this incident will inform the V6 release, including circuit updates that prevent the network from accepting proofs tied to an affected proving system.

V5 launched as Alpha software, with V6 planned for later in 2026. Contributors will publish a security roadmap covering the remaining work and release path.

Known vulnerability status

Reviewers have not identified other high-severity or critical V5 Alpha vulnerabilities at this time.

Internal and external human audits have completed, and contributors continue AI-assisted auditing. Alpha is the period for identifying faults before production deployment.

Community
Community
4 Aug
xx min read

Dark Forest Aztec Game Goes Live

Dark Forest is a real-time strategy game played across a procedurally generated universe where most of the map is hidden. You cannot see rival players, their planets, or their fleets. You only know what you have explored. Everyone shares one universe, and nobody has the full picture.

In most onchain games, every position and every move is public, because the chain is public. Dark Forest used zero-knowledge proofs to break that assumption: players prove their moves are valid without revealing where those moves came from. The result is a game of hidden information running on a public network.

Dark Forest Aztec ports the original Dark Forest 0.6 to Aztec. It keeps the gameplay from the original and rebuilds the privacy layer on Aztec's programmable privacy.

A note before diving in: this is early, experimental software on Aztec Alpha V5. Treat it as an alpha and play accordingly.

The universe you cannot see

You start on a single home planet with almost the entire map dark. To find anything you mine the universe, running a client that explores coordinates and reveals what sits there: unclaimed planets, resources, and eventually the edges of other players' territory.

You are never handed a view of the board. You earn it one region at a time, and everyone else works under the same fog.

What is hidden on Aztec

Your home coordinates and your fleet movements are private state, expressed as first-class private notes on Aztec. Your location and where you send energy stay hidden, enforced in the contracts by zero-knowledge cryptography.

What sits onchain is a set of cryptographic commitments. Instead of storing every planet's full details in the open, the contracts store Poseidon2 hashes of entity state. When you make a move, your client supplies the full state, the contract checks it against the stored hash, applies the change under zero-knowledge constraints, and writes a new hash back. Full game state lives offchain and gets rebuilt from public logs by an indexer, which is what renders your map without exposing every player's position.

So you can prove you made a legal move from a planet you own without revealing where that planet is. Aztec applies the same principle to private payments and private contracts.

How you play

Four actions carry the game.

Explore. Your explorer sits in the bottom left. Set it running and it uncovers the map around you, surfacing planets, resources, and other players.

Send energy. Most planets produce energy. Click and drag from a planet you own toward a target to capture or weaken it.

Route silver. Asteroid fields produce silver. Move it to your planets and spend it on upgrades, or send it to a Spacetime Rip to convert it into score.

Hunt artifacts. Some planets hold artifacts. Your Gear ship discovers them. Once harvested, you deposit them on planets to boost stats.

Four stats drive most decisions.

Energy is the core resource. Planets generate it over time up to a capacity, and you spend it on everything: claiming planets, reinforcing your own, attacking rivals. Two details matter. Moves are taxed, so a flat percentage of a planet's total capacity burns every time you send energy, which discourages small frequent moves. And energy decays over distance, so send it too far and almost nothing arrives. A common rule of thumb is to let a planet fill to about 75%, then send it down to about 25%.

Defense reduces the damage incoming energy does when it lands. Higher-level planets often have lower defense, but they hold much more energy, so they still take more to capture. Defense matters most on front lines.

Range sets how far a planet can send energy. It governs how fast you expand and how efficiently you move energy inside your own empire, since shorter relative distances mean less decay. Good range also lets you strike deep into an opponent's territory.

Speed sets how quickly a move arrives. Usually secondary, though a fast strike can land before a rival reacts, and some playstyles reward capturing many nearby planets quickly.

Planets can also be upgraded with silver and enhanced with artifacts. Space types carry different multipliers, from mild Nebula to punishing Dead Space, so where a planet sits changes how it plays.

How scoring works

There is a scoreboard, and territory alone does not win it. This round scores two activities: discovering artifacts with your Gear ship, and withdrawing silver through Spacetime Rips.

Point values from the in-game help page:

  • Each unit of silver withdrawn: 1
  • Common artifact: 2,000
  • Rare: 10,000
  • Epic: 200,000
  • Legendary: 3,000,000
  • Mythic: 20,000,000

Silver accrues one point at a time. A single Mythic artifact is worth twenty million of them, so artifact hunting decides rounds and silver withdrawal sets your floor.

Silver has two competing uses. Spend it on upgrades and your planets get stronger, extending range and hardening defense. Withdraw it through a Spacetime Rip and it becomes scored points, but it is gone. Every unit is a choice between building the empire and banking points.

Upgrades tend to win early, since a stronger empire reaches more asteroid fields and finds more artifacts. Late in a round that calculation flips, because a planet you never use is worth less than points already scored.

Artifacts do both jobs at once. They score on discovery, and once deposited they boost a planet's stats, which makes the next expedition easier.

Why you explore

Nothing happens until you find something to act on. Your explorer turns dark space into planets you can capture, asteroid fields you can mine, and artifact-bearing planets you can raid. Sitting still means no new energy, no silver, no score.

Exploring also buys information. The map you have uncovered is an advantage nobody else holds. Knowing where high-level planets sit, which asteroid fields are unclaimed, and where space types shift lets you plan further ahead than someone still working through their starting region.

You find other players as a byproduct. There is no player list. You explore outward until your revealed region touches territory someone already owns: a planet in another player's colors, sitting where you were about to expand. Their home coordinates stay private, so you learn something narrow. Someone is here, roughly this direction, holding this much. You infer the rest, and you have no way of knowing whether they found you first.

What happens when you run into someone

You have three broad options.

Stay quiet and keep growing. Nothing forces you to engage. Keep exploring elsewhere, keep routing silver, keep upgrading. Your positions stay private, so silence costs you only time, which is what you want if they are stronger. The risk is that they are doing the same thing faster.

Fortify the border. If the contact sits somewhere you cannot lose, spend energy hardening the planets facing them. Defense is worth most where an attack will actually land. This keeps the option to fight without committing to one.

Attack. Send enough energy to overwhelm the target's defense and the planet becomes yours, along with its production and its position as a staging post. Higher-level planets are the prize and take proportionally more to crack.

Attacking costs more than energy. A move that lands tells your rival where you strike from, and that you are close enough to be worth answering. Retaliation can then come from directions you have not explored, launched from planets you cannot see.

Multiplayer in practice

Everyone plays one shared universe in real time. No turns, no lobbies. Energy regenerates whether you are watching or not, moves stay in flight while you sleep, and rivals expand while you are away from the screen.

Most strategy games let you watch a threat approach. Here you tend to see the consequences: a planet you owned this morning in someone else's colors, an incoming move you notice once it is already close.

That produces a particular kind of paranoia. You are trying to find everyone else while avoiding being found, and every expansion is a strategic bet that the space ahead is empty.

Information becomes tradeable, because it is scarce. Players compare notes, warn each other about aggressive neighbors, and agree who expands where, then break those agreements when the scoreboard makes it worth breaking.

Why it matters beyond the game

A fully onchain game where players cannot see each other's positions is hard to build, and building it well says something about the platform underneath.

Hidden state, private notes, and client-side proving are the same building blocks behind private applications across Aztec. Dark Forest is a way to watch them work.

Getting started

Dark Forest Aztec is playable now as an alpha. Expect a learning curve; the original was famous for it. DFArchon maintains onboarding material and a community for new players. Round One is live. The universe is dark, and everyone else is out there somewhere. Go find them, quietly.

Play Now

Follow the Builders

DFArchon on X

Source and docs

Aztec Network
Aztec Network
22 Jul
xx min read

How Gas Works on Aztec

Gas on Aztec

Gas on Aztec is known as Fee Juice and is used to pay for transaction costs. This is the same as $ETH on Ethereum. Some apps will handle transaction costs for you under the hood, but if you are using a browser extension wallet, you will not be able to send transactions without it. Fee Juice can be obtained by bridging the $AZTEC token on Ethereum to the Aztec Network L2. This means that under the hood, all activity that happens on Aztec is underpinned by the $AZTEC token bridged into the network. Some bridges like Shield (by human.tech) handle this for you, allowing you to allocate a portion of your bridged transaction to convert into Fee Juice and land in your wallet automatically.

Public vs Private Assets

Assets and transactions on the Aztec Network can be either public or private. If you bridge publicly, your tokens will arrive as public, traceable tokens visible to all. Privately bridging, on the other hand, will give you private assets that are visible only to you. These assets can then be sent privately to another user or wallet without ever revealing who you are, what tokens were sent, how many, or who the recipient is.

Public vs Private Gas

Like tokens on the Aztec Network, Fee Juice (gas) can also be public or private. The reason for this is that even if what you are sending is private, the gas you spend to execute that transaction could still be visible if you are using public Fee Juice, potentially revealing transaction patterns and activity. Private Fee Juice keeps your entire transaction footprint hidden. When you send a private transaction, you can use private Fee Juice, and when you send a public transaction, you can use public Fee Juice, which means your transaction costs are always aligned with the type of transaction you're making.

Fee Juice in Apps

Aztec has native fee abstraction, which means apps could let you pay for transactions in any token you want, or cover your fees entirely. Apps like Nyx may choose to cover part or all of a user's transaction costs, or allow you to pay in tokens that are convenient for you. This means you will most likely never see Fee Juice in an app; instead, you'll pay in whatever makes sense for what you're doing, on your terms. Similarly, you might never even see an Aztec wallet at all, because the app itself becomes your interface that you connect to using your MetaMask wallet.

Fee Juice in Browser Wallets

If you're using a browser extension like Azguard, you'll manage Fee Juice directly in your wallet alongside your private and public balances, converting between tokens as needed to cover transaction costs.

When you bridge tokens in, you'll need enough Fee Juice to cover the cost of your first transaction, then you'll need to monitor how much Fee Juice you have available to make transactions. Browser wallets will allow you to send either publicly or privately to other users and will default to using either public or private Fee Juice depending on the type of transaction. Both private Fee Juice and public Fee Juice will appear by default in your token list.

Wrapping up

How you handle Fee Juice depends on where you're transacting: apps can abstract it away entirely and let you pay in any token, while a browser wallet like Azguard puts it in your hands to manage across public and private balances. Match your gas to your transaction, keep private activity private down to the fee, and you move on your terms.

Aztec Network
Aztec Network
21 Jul
xx min read

Introducing Alpha V5

The Aztec Network today activated Alpha V5, a major protocol upgrade passed by token-holder governance and executed onchain. Alpha V5 reduces private-transaction proving times by more than 2x compared to the previous version, lowers the cost of a fully private transaction by roughly 50%, resolves the critical issues found in V4, and sees the first wave of apps go live. Users can now send private transactions and earn yield on Aave simply by connecting their Ethereum wallets on Nyx, bridge from Ethereum to Aztec using Shield or TRAIN, privately collect NFTs on RavenHouse, or play Dark Forest Aztec, a hidden-information strategy game in a universe that lives entirely onchain. 

"Alpha V5 continues Aztec's work at the frontier of client-side proving, with cryptographic breakthroughs that cut proving times by more than half this release," said Zac Williamson, Co-founder, Aztec Foundation. "We believe Aztec is now the fastest system in the world for proving a fully private transaction entirely on a user's own device, and every release moves the industry closer to private transactions at public transaction speeds."

As the only decentralized L2, Aztec is the credibly neutral privacy layer for Ethereum. Aztec allows anyone to write smart contracts that include both private and public aspects – every private transaction is proven on the user's own device, so no operator, sequencer, or intermediary can see the data. The Alpha V5 proving improvements come from cryptographic advances that make this client-side proving faster than any prior release. The network remains in alpha, but with V5 it is ready for teams to begin building and deploying applications.

Performance - 2.5 second fully private transactions 

Making private transactions practical comes down to how quickly a proof can be generated on a user's own device, without offloading that work to a server that would learn what the user is doing. On Alpha V5, proving a private token transfer natively now takes approximately 2.5 seconds on a consumer laptop, down from 5.2 seconds on V4, and about 6.8 seconds in a browser, down from 12.5 seconds. Across every measured transaction flow, client-side proving times improved by approximately 2x compared with V4.

Bench machine: an M2 MacBook (12 cores, throttled to 8). "Native" runs Aztec's C++ proving binary; "WASM" runs the same prover in a browser engine (Node on V8).

Alpha V5 lowers ECDSA signature-verification cost by approximately 2x, speeds up Poseidon2 hashing by approximately 3x, and reduces the protocol circuit gate count by approximately 50% (gate count is the number of individual operations a proving circuit must perform, and it is the main driver of how long a proof takes to generate). Each of these lowers the amount of work a device performs to prove a transaction, and the reduction in gate count in particular compounds across every proof the network generates.

Apps - send, receive, and earn privately on Ethereum

Alpha V5 launches the first wave of apps on a network where privacy is built into the protocol rather than managed by an operator. On other networks that claim privacy, transactions still pass through an operator or node that reads them in plaintext, or depend on a viewing key that a third party holds, so users rely on someone else to protect their data and to decide when it gets disclosed. On Aztec, every private transaction is proven on the user's own device, so the app, the sequencer, and any operator never need to see the underlying data. Nyx is one of these apps, allowing users to privately send transactions and privately earn yield on Aave. 

"On Ethereum, everything you do is public. That's why we built Nyx: a private account governed by your Ethereum wallet", said Nikhil, Co-founder of Nyx. "Now you can send, receive and earn in private. Nyx was the first app live on the Aztec Alpha, and we're excited to expand participation to more users with the added stability of Alpha V5."

Other apps on Alpha V5 include Azguard and Nethermind (wallets), Shield, TRAIN, and RavenHouse (bridges), and the Aztecscan block explorers. Also launching is Dark Forest Aztec, a game where users explore a universe, control planets, manage planetary energy, expand territory, and launch attacks through strategic play with private state and hidden actions.

Dark Forest Aztec private universe-building gameplay

Lower costs, higher security 

Transaction fees on Aztec come from two main sources: the cost of proving a transaction and the cost of verifying the rollup proof on Ethereum. Alpha V5 reduces both. It lowers the network's proving-cost parameter by 50%, and it reduces the L1 gas required to verify a rollup proof by approximately 40%. Because rollup proofs are verified on Ethereum and that cost is shared across all transactions in a batch, the L1 reduction lowers fees for every user, while the lower proving-cost parameter reduces the per-transaction proving fee directly. Together, these bring the average cost of a fully private token transfer to under a $0.05 transaction cost.

Alpha V5 also hardens the network on several fronts. It resolves critical vulnerabilities found in Alpha V4 along with additional bugs discovered since launch. Aztec's bug bounty program on Cantina also drew more than 234 security researchers to participate. The network remains in alpha, and further bugs may surface as usage grows, but each release has closed the issues found in the last and strengthened the protocol against new ones. With the critical V4 issues resolved and these safeguards in place, Alpha V5 is stable enough for teams to begin building and deploying applications.

Availability

Alpha V5 is live now, view the Alpha V5 landing page for a full list of features, performance updates, and live apps to explore. 

About Aztec

Aztec is the only decentralized, privacy-first Layer 2 on Ethereum. Developers write private and public logic in the same smart contract, and private functions are executed and proven on the user's own device, so no operator sees the underlying data. The protocol is upgraded through onchain governance, and the network settles to Ethereum. For more information, visit aztec.network.