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Jun 26th, 2024
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## min read

Can blockchains and zero-knowledge help humanity survive? 47 real-world use cases

Worldwide, the average person’s daily screen time is 6 hours and 58 minutes. This is approximately 41% of waking time. Does it mean that a modern human is 41% digital?

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Written by
Lisa A.
Edited by

Are we becoming cyborgs in 2024?

Many thanks to Elias, Palla, Mahima, Hannes, and Rafal for review. Separate thanks to João Montenegro for an awesome discussion.

Worldwide, the average person’s daily screen time is 6 hours and 58 minutes. This is approximately 41% of waking time. Does it mean that a modern human is 41% digital?

Let’s think.

  • Personal relations are becoming digital (17% of marriages and 20% of relationships begin online) as well as business and consumer relations (81% of consumers prefer communicating in a messenger).
  • Society is becoming “cashless”: only 9% of Americans pay with cash, and in some countries it accounts for only 1% (e.g. Norway, Honk Kong, Sweden, etc.).
  • 71% of smartphone owners sleep with or next to their mobile phones.
  • Google search engine acts almost like humanity's hive-mind.
  • “Information and communications technologies are more widespread than electricity.” – Shoshana Zuboff.

One thing can be said for sure: our everyday life is a blend of the physical and digital worlds and this trend won’t reverse. Furthermore, the share of digital reality is going to grow.

Humanity has rich experience (approx. 300,000 years) living in physical reality.

Within this time we’ve learnt some useful skills. For example:

  • How to build reliable constructions such as houses, bridges, roller coasters, and military offices.
  • How to treat our bodies in such a way that they serve us as long as possible.
  • How to build meaningful relations that last for years and make us feel good, loved, and needed.

With digital reality, our experience is approximately 4,878x shorter (assuming 1983 being the internet’s year of birth). So, it seems we are still at the beginning of the learning curve of living in digital reality.

What part of ourselves is digital? Let’s think.

  • Most of our documents, files, and data (e.g. financial and health) are digital and stored on smartphones or laptops.
  • Most of our communications and social interactions are digital: through emails, social media, video calls, etc.
  • Most of our work is done digitally: collaborative work using Google services and GitHub, web services (e.g. Figma), storing and managing files in the cloud (e.g. Dropbox).
  • Most of our memorable moments and things that make us feel good are stored digitally: pictures from birthdays and weddings, screenshotted messages from those we love and hate, playlists we’ve been collecting for years, movie ratings, etc.
  • Authentications and passwords for all services and accounts we use.

What exactly does “digital” mean in all these cases? In most cases, it means stored in cloud services or on a company server. That is saying that 99.9% of our digital “us” is outside of our control.

Google won’t close tomorrow, will it?

Humans like to be optimistic. Google won’t close tomorrow, right? It just doesn’t make any sense. Humanity pays it so much money. Humanity gives it all its data.

Okay, thinking rationally, let’s assume that Google’s best option is to exist forever. But what about our Google accounts? What about the digital “us”? What about data authenticity? What about the part of our life that happens digitally every day? Will it exist tomorrow?

Let’s for a second move from that optimistic perspective to a more realistic one:

  • Whether we have access to our money or not depends on whether the bank allows us or not.
  • Whether we can access our iPhone or not depends on whether Apple allows us or not.
  • Whether we can access our data backup on iCloud depends on whether Apple allows us or not.
  • Whether we can leave a comment on a forum or social media depends on whether we meet the criteria of being a “good user” or not.

So, the first “layer” is: in order to have access to our digital life, we need to meet the criteria of being a “good customer” every day. Every single day. Doesn’t sound nice, but not a big deal, right?

Source

At the end of the day, we are good humans, we have nothing to hide, we trust our governments and these pretty multibillion corporations. They are nice guys. Is there anything else to worry about?

Hmm, let us think what happens if…

  • Artificial general intelligence (AGI) kidnaps the internet and floods it with bots?
  • Company servers are destroyed because of war or natural disasters?
  • Governmental databases break down, destroying all information about citizens and pushing the world into anarchy?
  • Autopilot transports and machinery get programmed for self-destruction on Wednesday 9:00 Eastern Time?
  • Banking system gets lost or corrupted, so we lose all our money because it is just a digital entry on a centralized server?

We still can stick to an optimistic mindset and say: okay, the probability of this happening is very low. Let’s wait until one such incident happens (e.g. nuclear war) and then we should start worrying. Today we still can access banking apps, scroll Instagram, and order a poke bowl. Why do we need to worry now?

There are several reasons to think about it today:

  1. We can’t think about saving the world after the world has been destroyed because the world won’t exist anymore.
  2. Saving the world might take time. A couple of seconds might not be enough. And if the world is going to be destroyed, no one will kindly tell us 20 years in advance.
  3. We still can eat poke while trying to save the world. There is no contradiction therein.

Now let’s be more precise. While appealing to “saving the world”, by “the world”, we mean “the digital world”, a part of our life and identity that exists purely online or in a hybrid state of offline and online (e.g. medical devices implanted into human bodies having software components). By “saving”, we mean making it robust. That is to say neither governments, corporations, AGI, nor bots can kidnap, destroy, control, or limit a digital part of us.

We must make the internet more robust

Comparing our physical reality to digital reality, if in the former we developed robust materials such as carbon, metal, glass, and ultra-high molecular weight polyethylene fiber, in the latter we are still building twig huts.

The good news is that today we are already equipped well enough to start making the internet more robust. Three components that will allow us to resist factors such as AGI or dictatorships are blockchains, privacy incorporated into blockchains, and cryptography. Why these three?

To have control of our digital “us”, we need four components:

  • Permissionlessness
  • Immutability
  • Verifiability
  • Privacy

Let’s abstract from the wording “the internet”. Instead, let’s use the word “cyberspace”, meaning “everything digital” including the internet, computer networks, and whatnot.

By permissionlessness, we mean that cyberspace is equal for any human on Earth. Create an account, deploy code, own a digital object, talk to another human in cyberspace – whatever is possible there for one human is possible for everyone.

By immutability, we mean that humans have control over their life in cyberspace and if they make an action in cyberspace (e.g. open an account, issue an ID, or deploy code), no one can undo it. One should note that immutability might work as a double-edged sword, as if being immutable means nothing can ever be forgotten. Thus, we should be very conscious while building of what exactly we are making immutable and how it might manifest as a negative externality one day.

By verifiability, we mean something like an objective source of truth. If human 54835934 tells human 82849934 that “this statement” is true, human 82849934 has a tool to objectively verify its truthfulness.

By privacy, we mean control over what is disclosed, when, and to whom. How sincere are we claiming “we have nothing to hide”? Even if we don’t mind “someone” having access to all our correspondence, medical data, pictures and videos (including those hot nudes), food delivery, e-commerce, and porn browser history… What if we take it one step further, right to brain-computer interfaces (BCI)? If someone (whether governments, corporations, AGI or another party with exceptionally good intentions) now has access to all our thoughts and body chemistry, do we still have nothing to hide?

These four properties allow us to ensure that our digital “us” will last at least as long as our physical “us” (or maybe even longer, but that is a topic for another article).

Blockchains and cryptography

No technology in isolation is a magic pill. However, combining the right technologies and applying them in the right cases allow us to come closer to inventing a magic pill.

Let’s first clarify what technologies we have in our “survival kit” and what properties of theirs we are interested in.

Blockchain provides permissionlessness and immutability

Blockchain is a shared, immutable ledger that facilitates the process of recording transactions and tracking assets in a network.

In this definition, the key property is “shared”. The question is how exactly it is shared or who are the participants of the network. To be shared “for real”, we want the blockchain to have thousands or even millions of nodes that are independent of each other. As of the 15th of April 2024, Ethereum has 5,912 nodes in the network where by nodes we mean different independent parties running infrastructure (one node might run many validators). And even though some of them are run by institutions, Ethereum can be fairly called a shared and immutable ledger. That is to say, Ethereum is good enough to be the base of the robust internet.

Cryptography provides verifiability

Cryptography’s history is almost as long as humanity’s history. But with the advent of the digital era, some specific kinds of cryptography that fit the needs of computers and the internet started evolving at an insane pace.

The history of zero-knowledge cryptography started in 1989, although it wasn’t obvious it would be a perfect complement for blockchains (even though the idea of blockchains was proposed earlier).

A zero-knowledge protocol consists of two parties, a Prover and a Verifier, where the Prover can prove to the Verifier that a certain huge statement is true while conveying only a tiny bit of information. This property is called “succinctness” and is a key component of cyberspace, where individuals need to coordinate with each other all the time and the communication has to be as lightweight as possible.

‍Privacy-preserving blockchains provide privacy

Privacy-preserving blockchains allow individuals to choose what information to disclose, when, to whom, and in what form. This is another crucial element of cyberspace, as disclosing one bit of data while preserving private other bits of data is a must-have mechanism for efficient coordination.

For example, in the case of elections, an individual wants to tell the tally that (i) they are eligible to vote, (ii) they have voted, (iii) they voted only once, but they don’t want to disclose any details about their vote or their identity.

One should note that privacy on the application layer (e.g. private identity or transfers) can’t be added to a transparent blockchain purely by means of cryptography. Privacy should be incorporated into blockchain design at the level of smart contract anatomy and state management.

Now that we’ve looked at what components we need to build robust cyberspace, let’s explore specific cases we need to fix and decide if we really can fix them with these tools.

47 use cases and 75 examples for blockchains, privacy, and zero-knowledge

In the second part of this article, we will explore 47 use cases and 75 examples of how blockchains, privacy, and verifiability can disrupt, heal, expand, and modify the world around us, addressing its problems, weaknesses, points of failure, and fragilities.

But before we dive into the full list, let’s cover three quick examples as an introductory illustration:

  1. Programmable identity: Today, when someone needs to confirm their identity, age, citizenship, or residential address, they provide a passport, ID, or other formal documents. With zero-knowledge proofs, one can manage all their documents client-side and provide proofs of specific properties upon request, without requiring documents.

One should note that for this use case we strictly need privacy-preserving composable blockchain (e.g. Aztec).

  1. Combining several data sets and a model without datasets and model disclosure between parties.
  1. Smart home that processes all data client-side (i.e. inside of smart home) without sharing its inhabitants’ data with anyone (even Google!).

Now we have some intuition behind how zero-knowledge proofs and privacy-preserving blockchains can create an alternative to the current reality, with several of the cases we’ve mentioned involving fixing data privacy and individual sovereignty issues and unlocking new forms of collaboration and coordination. Finally we are ready to dive into the longlist of blockchain, privacy, and verifiability use cases, where these three factors become the real game changers for the world and humanity’s future.

Most of the ideas described below were borrowed from brilliant minds, either from their public presentations or personal talks. Credit to Barry, Steven, Zac, freeatnet.eth, Jessica, Henry, Tarun, and Joe for being brilliant minds.

We will also categorize all use cases into categories:

  1. Efficient coordination – allows small numbers of individuals coordinating efficiently to compete with much larger agents.
  2. Verifiable computation – “truth objectivity” allows individuals to be sure that something is true without relying on honesty of institutions or other individuals.
  3. Data immutability and robustness – makes the cyberspace environment more long-lasting, reliable, and independent of institutions and individual agents.
  4. Improved world economic efficiency – allows individuals and institutions to utilize the resources at their disposal in a more economically efficient manner.
  5. Privacy – just privacy.

In the table below, we categorize a number of solutions to specific problems we will probably meet within the next decades while the digital share of the world is expanding and rooting deeper and deeper into our reality. We classify them according to whether they require blockchain, privacy, verifiability (provided by zero-knowledge), or a specific combination of these three. In most cases, blockchain serves as a coordination layer, privacy is engaged in all cases where participants can’t go with 100% transparency of all data, and zero-knowledge adds verifiability.

Under blockchain, we assume a decentralized one where nodes are run by thousands of diverse, independent parties. This decentralization makes the network credibly neutral and provides strong security guarantees. Today, Ethereum fits this criteria more than anything else. Layers 2 on top of Ethereum inherit its security property, however, their credible neutrality depends on design details such as approach to block building and upgrade mechanism.

Under privacy, we mean that whatever we want to stay private should be fully processed client-side on the user's device and should not be exposed to any other parties.

We also consider combining blockchain, privacy, and zero-knowledge with other existing technologies such as:

  • MPC and 2PC – enables multiple parties (or two parties in 2PC case) – each holding their own private/secret data – to compute the value of a public function using that private data while keeping their own piece of data secret.
  • TEE – a secure area of a main processor that prevents unauthorized entities from outside the TEE from reading data, and prevents code in the TEE from being replaced or modified by unauthorized entities.
  • Any existing cryptographic primitive such as an ECDSA signature (an example of a public key cryptography encryption algorithm).

Why can't we use these technologies separately and why do we need to combine them with zero knowledge and blockchain? Because we don’t just want to trust those using them that they are acting in good faith; we want to be able to verify that they are acting in good faith.

Efficient coordination

Use case Blockchain Privacy Verifiability
Proof of eligibility (for participation, access, etc.) Example 1: Access to the building (e.g. office).
Example 2: Access to military data regarding ongoing war where if this data is leaked it will lead to numbers of deaths.
Optional Need Need
Proof of innocence
Example: Compliance (proof of not interacting with agents meeting specific criteria, e.g. North Korean hackers).
Need Need Need
A mechanism ensuring collective agreement for making crucial decisions
Example 1: Minimum threshold for pushing the nuclear button where the voting members represent all parties that should be represented in a fair manner (MPC+ZK).
Example 2: Minimum threshold to approve decisions of the board of directors with huge financial impact.
Need Need Need
Prevention from malicious cooperation such as bribery or voting system “tampering” Example 1: Voting mechanism where it is impossible to prove that one has voted for a specific candidate.Example 2: Voters can independently verify that their vote was fairly recorded in the election tally. Need Need Need
“Programmable” trust: verification of specific properties of individuals (e.g. belonging to specific groups, visiting specific events, etc.) that allows the building of “safe spaces”
Example: If one studied at the same university and is a member of the same charity organization, it increases the probability that we share similar values and my default trust in this person can rationally be higher than in those who don’t meet these properties.
Need Need Need
“Temperature check” before making decisions/actions with extremely high general costs or the cost of being among the first.
Example: A government member can check how many other government members are ready to oppose the current ruling coalition and start to act only if they are sure they will have sufficient supporters (MPC+ZK).
Need Need Need
Check the alignment or expectations regarding a specific question in a neutral way as (i) participants don’t need to disclose sensitive information to each other and (ii) no one needs to express their preferences first, so there is no time priority.
Example 1: Negotiation of salary between the employer and employee where no single party needs to reveal their preference first, allowing the second party to adjust their preferences based on the disclosed information.
Example 2: Negotiation of the type of relationship that works best of all for all participants, such as “Should friends start romantic relationships”? (2PC+ZK or MPC+ZK depending on the number of participants).
Need Need Need
Private DAOs as a type of a legal entity
Example: Programmable organization with task-based system where compensation payments fully depend on executed milestones.
Need Need Need
Neutral personal data regulation
Example: Instead of governments enforcing the laws and standards around personal data (e.g. the EU’s GDPR), these standards are designed and regulated by a neutral third party while its execution is verifiable.
Need Need Need
Fair incentives mechanisms
Example: Corporations commit to a specific max level of negative externality regarding the greenhouse effect. If the max level is exceeded even by a tiny amount, the agent is “slashed”. By slashed we might mean monetary or other types of slashing (e.g. “reputational slashing” through public reporting for a worldwide audience).
Need Need Need
Blended experience between offline and online domains
Example: Pokémon Go, where blockchain serves as a coordination layer for a number of players.
Need Need Need

Verifiable computations / truth objectivity

Use case Blockchain Privacy zk
Ensuring that an autonomous automatic system will work exactly in the way it is expected to work (i.e. according to the designed algorithm)Example: Self-driving cars, autopilot planes, and self-navigating rockets can execute only the algorithm they committed to. Optional Optional Need
Executing the algorithm while keeping it a secret, i.e. executing any algorithm that should be executed by an external party while the algorithm owner would prefer not to disclose the underlying mechanism (either for commercial or personal motivations)
Example: Dating matching algorithm (2PC/MPC+ZK).
Optional Need Need
Content authenticity: verifying specific criteria of content (pictures, videos, etc.) such as no-edits, produced by a human, time and place of production, etc.
Example: Distinguishing between deepfakes and authentic sources.
Optional Optional Need
Ensuring that some technology was used in a proper way
Example 1: Ensuring that FHE encryption for cloud data storage was done correctly.Example 2: Zk-snark wrapped up around an NFC signature from a chip's public key to prove that one owns a valid signature without revealing the raw signature itself.
Optional Need Need
Direct data verification from a web2 service
Example: Verifying one’s Twitter username to be used in an external (non-twitter) service.
Optional Need Need
Optimizing subjective manual processes by converting them into objective non-manualExample: Today, to confirm a bank transfer over a specific threshold, one needs to confirm this transfer manually through the bank call center. This manual process can be eliminated by using zero-knowledge proof to pass the bank’s security check. Optional Optional Need
Converting post-factum verification/check into preliminary
Example: In the modern blockchain world, compliance and KYC information is supplied post-factum, after the transaction was executed when it might be too late to address it. Using zero-knowledge, the transaction can be valid only if the counterparties proved that they meet a specific criteria (e.g. possess some kyc token provided by some kyc provider). Hence, any fraud attempts can be handled in time.
Need Need Need
Proof of ML models’ integrity
Example 1: The model owner proves that the result of the ML model running is fair without revealing any information about the model itself.Example 2: Proving that the submitted model was executed on the committed data without revealing data. Combining both examples, the model owner publicly commits to a model, and generates a zk-proof that the committed model was applied to the user’s submitted input, yielding the claimed result.Example 3: In case of LLM making decisions on its own (e.g. shouting military goals), proving how LLM made the decision when the information is fragmented and different parties have access to different fragments. One should be able to see how the data was put together and be able to question it without revealing all data to one specific party.
Optional Need Need
Proof of treating all participants in the same wayExample: Proof of no price discrimination. Need Need Need
Verifiability in supply chains
Example 1: Proving the origin and authenticity of goods and materials.
Example 2: Proving that materials meet compliance standards of supply chains within modern economies without revealing sensitive corporate information such as the identities of their suppliers and customers.
Need Need Need
Verified rating services
Example: Employer review (e.g. Glassdoor) where all the reviewers (i) stay anonymous, (ii) provide proofs of being eligible to review specific company/role.
Need Need Need
Proof of a mistake in a decision made by big data machine
Example 1: If one’s transaction was identified as a fraud but it is not, one can generate verifiable proof that the transaction is legitimate.
Example 2: If one was marked as an individual affiliated with a specific person (e.g. a terrorist) when one is not, one can generate verifiable proof that there are no connections/interactions with this party.
Optional Optional Need
List of attested events (created client-side) based on the data stream
Example 1: Using zk email as a data stream, based on the parking bill from a government authority, to generate a proof that the email owner has a car and lives in a specific city.
Example 2: Based on the shipment delivery updates delivered through zk email, generate a proof of order delivery.
Optional Need Need

Data immutability and robustness

Use case Blockchain Privacy zk
Robustness of interoperability Example: Guaranteed access configurations to Twitter API. That is to say Twitter can’t withdraw or modify this API version and thus break the operations of those using it. Need Need Need
Games/virtual worlds ownershipExample: Games’ immutability protects gamers from game studios’ “dictatorship”, enforcing the ownership over game assets and rules, which is meaningful for professional gamers who spend a huge chunk of their lives playing. Need Need Optional
Immutability for ownership guarantee
Example 1: Impossibility of suspending social media accounts by automated algorithms (especially those with large audiences, e.g. creators) without proof of violation.
Example 2: Impossibility of freezing ad accounts in social media by automated algorithms without proof of violation.
Optional Need Need
Signed internet history that is recoverable in case of web2 internet servers destruction (e.g. putting every internet website as a rollup)
Example 1: Proving data authenticity in case of “sybil attacks”. Example 2: Resisting AI DDOS attack.
Example 3: Impossibility of malicious power’s actions because of data immutability (e.g. revocation of citizenship).
Example 4: Preserving core digital infrastructure in case of internet shutdown/firewalling/censoring (e.g. in case of revolution or war in countries with oppressive regimes).
Need Need Need
A “car” transferring sealed data between various web2 and web3 services (as an alternative to current API mechanism). This allows (i) avoid trusting APIs (e.g. Facebook), (ii) get the data in the format one needs, (iii) data authenticity is verifiable.Example 1: Web2 and web3 oracles.
Example 2: Services built on top of existing services such as “who unfollowed me” on top of Instagram.
Example 3: Cross-chain verification.
Need Need Need
Physical and digital property ownership history
Example: Verifiable ownership history of rare antiques or pieces of art.
Need Need Need
Eliminating the risks of personal database leaks: because of client-side personal data processing, there is no need for collecting and storing huge personal data databases that can be leaked or hacked Need Need Need

Efficiency

Use case Blockchain Privacy zk
Creating global settlement layer of the world’s assets: digitizing real-world assets (e.g. property, pieces of art, IP, etc) to be able to use them in the digital world
Example: Use physical assets as collateral for digital lending.
Need Dearly need Need
Improving efficiency of decentralized services so that they are able to compete with centralized ones
Example: For democracies (which require a lot of multiparty coordination) to be able to compete with the authoritarian regimes that are highly centralized and coordinated.
Need Need Need
Neutral databases of authorized attestations
Example: Proof of holding a certificate issued by the International Culinary Institute that can be verified by anyone without additional requests to the institution that issued it.
Need Need Need
DeFi as an alternative to traditional financial institutions to (i) provide banking services for underbanked parts of the world, (ii) provide humans with censorship resistance and immutability where institutions can’t limit access to assets and number of allowed actions. One should note that even though we have been talking about DeFi for quite a while, the DeFi we have today is fully transparent. That is to say, if one borrows money, everyone can see it, all payments (e.g. salaries), savings, and assets are easily observable. To make DeFi the real alternative to traditional financial institutions, we need privacy-preserving composable blockchains, otherwise it’s a toy example.
Example 1: Buying stablecoins in countries where people are not allowed to buy foreign currency.
Example 2: Immutable private transactions or private compliant transactions.
Example 3: Providing basic banking services in countries with low GDP and weak institutions that can’t provide their population with access to banking.
Example 4: Broker-dealer network for securities trading services.
Need Deadly need Need
By reducing the amount of data that needs to be transmitted and processed, ZKPs can also significantly reduce the energy demands of IoT devices, improving efficiency and reducing costs. Optional Optional Need
Programmable spending based on the on-chain income
Example: Recurring monthly debt payment as the first spending from the salary.
Need Need Optional

To glimpse how all these use cases are possible through combining zero-knowledge and privacy-preserving blockchains, one should note that even though these technologies are absolutely awesome, they are still not magic pills. We need developers, engineers, and architects to combine them in smart ways. That is to say that the real magic pills are the developers, engineers, and architects capable of doing this and caring about our common future as much as the Aztec team does.

The components (i.e. blockchain, privacy, and verifiability) have been clear at a theoretical level for years. But even when they started to be implemented, most implementations were not really feasible for real-world usage and were hard to combine with each other. This was a serious issue, as web3 applications should be competitive with the existing web2 stuff we already use.

Aztec Labs addressed this issue and has been developing Noir, an open-source, domain-specific language that makes it easy for developers to write programs with arbitrary programmable logic, zero-knowledge proofs, and composable privacy. The program logic can vary from simple “I know X such that X < Y” to complex RSA signature verification. If you’re curious about Noir, check the talk “Learn Noir in an afternoon” by José Pedro Sousa.

Privacy-preserving blockchain and zero-knowledge in spacetech and defense

For those who are still skeptical about these 47 use cases above as too cypherpunk-ish, the next section talks about the need for privacy-preserving blockchains and zero-knowledge cryptography in a very specific domain for solving very specific problems.

Blockchains and zero-knowledge in space

Today, operating in near-Earth space is a part of everyday life: countries, industries, and businesses rely on the day-to-day operation of satellites and the complex infrastructure created in Earth’s orbit. That is to say, a number of parties (some of them are obviously hostile towards each other) manage a number of programmable “nodes” with sensitive data. That sounds exactly like a coordination problem that privacy-preserving blockchains and zero-knowledge are able to handle!

‍

  • Case 1: satellite coordination
    Most large countries have their satellites flying in space for some specific missions. That reminds one of car or plane traffic, but instead there are a number of satellites going from point A to point B. The goal is to manage this traffic in a way that there are no collisions or accidents. The coordination problem is that space is everyone’s – that is, the model of plane traffic doesn’t work.

Instead, satellite owners have to coordinate with each other (and as a consequence trust each other) to negotiate space management. This requires pretty deep data disclosure and trust that other parties have good intentions.

We can utilize zero-knowledge to provide proof of correct code execution, meaning that the satellite will perform exactly what its owner promises. For example, it can generate “proof of route”, which is a crucial component of space coordination as one additional zero in the code can send the satellite spinning forever or force it to change its trajectory and crash into other satellites. Privacy-preserving blockchain can be used as a coordination layer to deploy protocols for specific use cases.

  • Case 2: operating over hostile areas
    Sometimes satellites need to fly over the area of the countries with whom they are “not friends”. While flying over these areas, enemy representatives might be interested in hacking the satellite, intervening in its operating activity, and data forgery. For example, providing AI-generated images instead of authentic ones. To mitigate this risk, we can use zero-knowledge to provide proof of data authenticity or proof of metadata.

  • Case 3: planetary defense
    Planetary defense is the effort to monitor and protect Earth from asteroids, comets, and other objects in space. Life on Earth has been drastically altered by asteroid impacts before. For example, once a planet-shaking strike led to the extinction of the non-avian dinosaurs.
    Planetary defense combines comet and asteroid detection, trajectory assessment, tracking over time, and developing tools for possible collision prevention (includes slamming a spacecraft into the target, pulling it using gravity, and nuclear explosions).
    Planetary defense is operated by NASA, the European Space Agency, and other organizations, all representing different countries and dealing with sensitive data collection and secret technologies (e.g. satellite engineering mechanisms).
    ZKPs and privacy-preserving blockchains can be a coordination layer to process data collected by different parties without exposing it to others.  

Blockchains and zero-knowledge for LLMs on battlefields, enterprise, and everyone’s daily lives

LLMs are (today, already, obviously) very valuable, are shaping an absolutely different economy, and will have a huge impact on daily humans’ lives, geopolitical balance, and enterprise operations.

One of the issues with LLMs is that they can’t tell you how they reached their conclusions. However, some of these conclusions change the world and impact millions, if not billions, of people, being used for business, for countries, for battlefields. Take for example the case of using LLMs to detect targets on a battlefield. The model tells the commander “This is the target”, but it doesn’t provide any proof that this target was detected correctly. In this case, the cost of wrong detection is at least a life, maybe a dozen lives, or several hundred thousand lives.

Zero-knowledge proofs can be a “neutral arbiter” providing the proof of what data the model was trained on, what data the model used to make a conclusion, how this data was put together, what the underlying algorithm is, etc. Furthermore, it can be done without revealing any specific information about either the data or the model.

One should note that today we are not talking about whether or not we should use LLMs for specific use cases. The reality is they are already used everywhere, by all major corporations, countries, and their governments. But what we still are able to do while LLMs start flooding our world is make the model owners accountable for their models – that is to say enforce some formal LLM compliance.

Similar to private data processing and collection today, some legislation for AI regulation will be set up as well. However, mere legislation is not enough; standards should be transparent and equal for everyone, and they should be followed.

Can a trusted third party who is believable, shares pro-democratic values, and is neutral enforce legislation compliance? In a domain such as AI, where at stakes are at the very least huge amounts of money (if not shaping the geopolitical landscape of the world for years to come), there are no neutral parties – everyone has their own interests and skin in the game.

In LLMs we don’t have custodial relations to the data, we can’t prove how the decision was made. But at the same time, we need to know how the data was put together and be able to question it. That is, for example, an absolute necessity for the presumption of innocence. ZKPs as a source of truth and privacy-preserving blockchains as a coordination layer can solve this issue to enforce AI standards compliance.

Conclusion

We are just at the very beginning. Privacy-preserving blockchains and zero-knowledge cryptography are needed in spacetech, agrotech, medtech, biotech, AI/ML, military technology, social networks, retail, robotics, big data, IoT, media and entertainment, edtech, fintech, logistics, neurotech, etc.

The 47 use cases mentioned above are kind of obvious today, but the real landscape of ZKPs and blockchain usage in 20 years will be much wider, deeper, and more diverse. Some of them can be predicted today, while some of them are almost impossible to imagine (unless you’re a true visionary).

One thing is absolutely clear, however: world verifiability is an absolutely required property while our world merges offline and online universes deeper and deeper. ZKPs as a “source of truth” and privacy-preserving blockchains as a coordination layer are a very promising duo to make the world verifiable.

It will take us time. The right moment to start was yesterday. But today is also a good day: for those ready to act together with Aztec – fill in the form.

Sources:

  • An article “Planetary defense: Protecting Earth from space-based threats” by Vicky Stein.
  • A talk “on The Global Tech Race” by Alex Karp.
  • A talk “Charting Taiwan DID as a Showcase & Experiment” by Noah Yeh.
  • A talk “State of ZK ECDSA” by Gauthier.
  • A talk 2PC is for Lovers by Barry Whitehat.
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Aztec Network
Aztec Network
15 Oct
•
xx min read

Post-Quantum Aztec

All blockchains today – L1s, L2s, and shielded pools – make use of elliptic curves somewhere in their stack.

Elliptic curves are used in all sorts of places: signing transactions, validator attestations, data availability (such as blobs), zk-snarks, secret sharing, encryption, etc.

No cryptocurrency project today is 100% quantum-proof.

Nobody has a reliable date for when a quantum computer will break the elliptic-curve cryptography we use today, but we know it’s coming.

For a privacy network, some of the work cannot wait for that uncertainty to resolve. An attacker could collect encrypted data today and keep it until they have the means to decrypt it. This is the so-called “Harvest now; decrypt later” attack. Replacing an encryption scheme ten years from now would not protect the data an attacker already harvested under a classical encryption scheme.

Aztec is already quantum resistant against this type of attack. It was designed from the ground up to allow users to bunker-proof their accounts and data against quantum computers.

However, there is work to be done to make Aztec fully quantum secure and able to function with full privacy in the post-quantum world. 

Our roadmap to expand our quantum security has two targets:

  • February 2027: Hardened libraries and better off-the-shelf contract development patterns that protect against harvest-now-decrypt-later attacks
  • 2030: a full post-quantum migration.

The first requires changes to how applications handle private data. The second reaches into the proving system, account authentication, key derivation, validator signatures and Ethereum settlement. Understanding why these need different schedules requires getting into the cryptography.

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The risk of changing cryptography

Years of hard-won experience have taught us that the greatest risk to a network like Aztec is implementation bugs. Our AI audit harness has found critical vulnerabilities, including ones that months of expert human internal and external audits didn’t find. These have been patched in the upcoming v6 Aztec Network release. We have spent the past 18 months hardening our software and cryptography. That work has to continue while we develop their replacements.

AI also changes cryptanalysis. For example, the attack on HAWK (a post-quantum signature scheme) exploited structure specific to that signature scheme and reduced its security enough to end its candidacy for standardization. That is a reason to examine the assumptions and structure of each scheme with care.

Rushing headfirst into new cryptography that has not faced enough scrutiny would expose users to immediate risks, greater than the speculative risks of quantum computers. The Foundation has finite resources, and time spent on the post-quantum migration is time we have to balance against securing the software users depend on today.

Our default approach to changing cryptography is conservative. Any changes to our protocols must be justified, subjected to extraordinary cryptanalysis and have formally-verified implementations.

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Making Aztec post-quantum

To make Aztec post-quantum requires several pieces of cryptography. Aztec has an application layer (smart contracts), the Aztec protocol layer, and it settles on Ethereum itself. All three have responsibilities with respect to post-quantum security.

Protocol layer changes required:

1. Proving System

  • A post-quantum zero-knowledge proving system. Our unique requirements as a decentralized programmable privacy protocol present unique challenges, explained later.

2. Addresses & Keys

  • Changes to Aztec addresses and public keys, which are all elliptic curve points.
  • (These current addresses & keys can be used in a quantum-safe way today, though).
  1. Validator Keys & Signatures:
  • post-quantum digital signature scheme for Aztec’s decentralised validators’ attestations. 
  1. Adoption of the required Ethereum changes outlined below.

Application layer changes required:

  1. Post-quantum digital signature schemes.
  2. Post-quantum KEMs (secret sharing mechanisms).
  3. Post-quantum public-key encryption.

Ethereum changes required:

  1. DA
  • A DA layer that doesn’t use BLS12-381 KZG commitments.
  1. Verification Primitives
  • Cheap post-quantum snark verification primitives, as an alternative to the currently cheap de facto BN254 EVM precompiles.
  1. Public Keys & Signatures
  • Ethereum EoA public keys and signatures
  • Ethereum’s BLS keys.

The latter application layer requirements are not on Ethereum’s post-quantum roadmap as they’re a unique requirement of privacy protocols like Aztec and ZCash.

Notice that the bulk of the changes required for user privacy are dictated by the choices of Aztec smart contract developers at the application layer. Apps can adopt post-quantum encryption and signature schemes today on Aztec, and different Aztec smart contract developers can freely explore differing approaches as the state of the art in post-quantum advances.

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Protecting private data now

If and when quantum computers arrive, Aztec is already (uniquely for privacy protocols) protected in two key categories because of our existing design choices.

  1. A post-quantum proof system can securely use historical state created today 
  2. By default, historical state (including encrypted logs) is not vulnerable to “harvest-now-decrypt-later” attacks

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“Traditional” messaging in privacy protocols 

If I send you private tokens, there’s no onchain public balance update for you to see or query. Private state is stored in notes, so I need to tell you about the existence and contents of your new note for you to be able to use it.

A common solution is for me to publish an encrypted message to a public bulletin board that your wallet can find and decrypt. ZCash pioneered this approach.

Elliptic curve key exchange protocols are well-suited to this, because the amount of data I need to publish to convey “this is for you” and “here’s the ephemeral key you’ll need to decrypt this message” is a single ECDH ephemeral public key; an elliptic curve point; a tiny 32 bytes of info. We like this small communication overhead, because less data means faster tx throughput and cheaper DA costs passed on to users.

But elliptic-curve key exchanges can create a harvest-now-decrypt-later risk. The discrete log of such an ephemeral public key will one day be solvable by a quantum adversary. They could derive all ephemeral secret keys of all messages in the bulletin board. They’d then be able to brute-force combine the resulting list of ephemeral secret keys with a list of all known users’ viewing public keys to effectively derive all decryption keys on the network, to then decrypt all encrypted messages. They’d learn the contents of the note I sent you: the amount and that it belongs to you.

There are a few classical (pre-quantum) solutions to this. They follow from the observation that if an attacker doesn’t know one of: your public key or the ephemeral public key, then they won’t have enough information to decrypt any of your encrypted messages! Wallets are beginning to adopt the following:

  1. Don’t publicly share your public keys.
  • This is easier said than done. It defies the initial design intentions of public key cryptography. After all, you’d need to give me your public key for me to send you money! What if you share it with a dishonest counterparty, or an honest counterparty whose data leaks accidentally? This leads to another protection:
  1. Use a new public key for every new transaction.
  • That way, you stem any leakage if any of those public keys does leak. Some wallets of some privacy protocols already do this.
  1. Don’t broadcast any ephemeral public keys to a public bulletin board.
  • If ephemeral public keys aren’t seen by a quantum adversary, they can’t decrypt your messages, regardless of whether your address is public. Share this data through some private communication channel instead.

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Aztec Public Keys are hashed

Intentionally, most of the public keys in the Aztec protocol are hashed to reduce their leakage to a future post-quantum adversary. The public keys are not even exposed to Aztec smart contracts (which could be malicious).

(Private smart contract protocols even have a niche “harvest now; link later” attack to protect against, whereby a quantum adversary could link all your notes and nullifiers together to reconstruct your entire tx graph. Hashing the nullifier public key resolves this).

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Aztec is flexible, today

The Aztec Protocol is agnostic to the way in which users and applications (smart contracts) share private information between each other. It’s a beautifully flexible protocol because we knew times would change. Smart contract developers can adopt the above conventions today, and indeed many are doing so.

Aztec smart contracts can emit arbitrary bytes of data as “private logs”. These private logs are the intended delivery mechanism for sending encrypted notes. It’s up to smart contract developers how they populate those logs. I.e. they can choose:

  • Whether to use these private logs at all;
  • How to get the recipient’s attention;
  • How to convey the decryption key;
  • Which encryption scheme to use.

Aztec also supports offchain note delivery, which gives applications another secure option. A sender delivers the message through an off-chain side channel that is not visible to harvest-now-decrypt-later attackers.

All this flexibility in today’s Aztec Protocol enables Aztec smart contract developers to explore the tradeoff space in a way that best serves their users and use cases. Choices will need to balance: proving speed; DA costs; discovery of pertinent notes; post-quantum threats.

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Better libraries

Of course, most smart contract developers don’t want to think about such things, which is why the Aztec ecosystem has smart contract libraries with off-the-shelf solutions.

Our early 2027 work will focus on hardening these libraries and giving Aztec developers better patterns for protecting their users’ private data, with clear requirements for delivery and secret establishment.

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Post-quantum secret sharing

A more comforting solution to post-quantum worries would be for Aztec smart contracts to instead adopt post-quantum secret sharing and encryption schemes. 

We’re researching the best approaches and working on some tidy libraries. The good thing is, the agnosticism of the Aztec Protocol means multiple libraries for differing post-quantum secret sharing schemes can be written and adopted by different applications on Aztec.

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Constrained Delivery

In most other privacy protocols, the construction of an encrypted note is not constrained by any circuit.

For example, if I send you ZCash tokens, the ‘transfer’ function does not constrain that I have correctly encrypted your note, nor that I have attached the correct ephemeral public key that would enable you to discover and decrypt your encrypted note. I could technically broadcast garbage and you wouldn’t receive your funds. That’s arguably fine in a “simple” transfer protocol. It’s not in my interest to corrupt the encrypted notes that I create for you. After all, you can just claim I didn’t pay you until you do receive a valid and decryptable message. 

But when you generalise beyond simple transfers to private smart contracts, there are use cases whereby a sender might not be incentivised to deliver valid data to a recipient. The sender might actually prefer to corrupt a recipient’s data. Imagine a private swap. The contract should not complete the trade if one party receives a commitment to a note whose contents they cannot recover.

In such cases, the private functions (circuits) need to constrain that a recipient will be capable of discovering and decrypting a sender’s encrypted messages. Aztec’s smart contract libraries have rails for this so-called “constrained delivery”. If a use case assumes distrust between sender and recipient, the smart contract developer can enforce their correct adherence to the rules. The protocol then constrains that all private logs emitted by smart contracts are guaranteed to be broadcast – without tampering – to Ethereum blobs.

With this in mind, the constraints required to support post-quantum encryption then become a very important consideration. We’ll need post-quantum libraries that are efficient to prove.

Key and ciphertext sizes matter, but so does the cost of proving the key exchange, encryption and associated checks. A scheme can be fast as native software and expensive inside a circuit.

MIKE, published on 6 October, illustrates why this remains an active research question. It is an isogeny-based non-interactive key-exchange proposal. Its authors report 80-byte public keys and shared-secret computation, including key validation, in 4.9 milliseconds on a 3.3 GHz AMD CPU at their claimed NIST level 1.

Compact keys are attractive for note delivery. We still need to understand its circuit costs and give its security assumptions time to face scrutiny. Those native timings cannot tell us whether it is the right choice for Aztec.

The encryption and proving-system decisions therefore affect each other. Choosing encryption first and discovering that it is prohibitively expensive in the chosen prover would leave us rebuilding one of them.

Choosing the encryption scheme we will prove inside future post-quantum circuits is a separate, later milestone. Applications that need the contract itself to guarantee delivery impose harder requirements on that choice.

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Post-Quantum Proving

Ok, so Aztec provides flexibility for good post-quantum privacy today. And we have plans to roll out even better post-quantum libraries.

But what about the proving system? A post-quantum adversary might be able to forge proofs. Thankfully we have some more time to choose a post-quantum proving system.

Aztec has several proving system requirements that other projects aren’t encumbered by (due to our commitment to both privacy, decentralisation and programmability), which we’ll elaborate on.

  • Low memory and CPU requirements: proving must be possible on a phone, in the browser.
  • Actual zero-knowledge!
  • Fast client-side recursion.
  • Small client-side proof sizes.
  • Cheap L1 verification.
  • Simple, maintainable, and secure.

Common benchmarks for proving system performance don’t take into consideration all these requirements. Fast client-side recursion in particular is often overlooked.

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The problem with recursion

Aztec uses CHONK, an elliptic-curve and pairing-based proving system built around the requirements of private smart contracts. Users generate proofs on their own devices, and a transaction can involve several private contract calls. Recursion lets us combine those calls into a proof of the transaction without requiring the browser to handle the entire computation as one enormous circuit. CHONK’s design puts low memory use and recursive composition at its centre.

There are tradeoffs you can make to get a faster prover. Some give the verifier more work. A custom “precompile” circuit for an expensive operation can save the prover from executing that operation through thousands of VM instructions, but introduces additional commitments and checks that increases Verifier complexity.

The problem is that, in the recursive setting, your verifier is in your prover. The next proof has to establish that the verifier accepted the previous proof.

I have lost count of the conversations about new prover technology where recursion gets a handwave and a “we’ll deal with it later.” It is a complex, messy problem that is easy to postpone until you need users to generate private transaction proofs in a browser.

Some alternative designs might execute an entire function stack within a single VM instance. That might work for some bounded stack depth. But snarks are gaining traction in web2 too (see zkPassport for example). Bridging between chains also often requires snarks. Privacy protocols should be able to verify traditional snarks for as long as we remain in a pre-quantum world. 

Zero knowledge introduces another set of costs. I have heard the same assurances that adding it will be easy and will not affect performance. From personal experience, such claims often disintegrate on contact with reality.

We thought adding zero knowledge to CHONK would be easy. It took us six months and a re-architecture of our recursive proving stack. Modern proof systems have such complexity that throwing randomness into the execution trace and calling it a day almost never works. Adding ZK typically increases proof size and verifier work, which then increases the cost of recursion.

The result is that the real cost of recursion in a production proving system, with all of the edge-cases and exceptions and little additions that pile up, is never as fast as the initial proof-of-concept claims. For Aztec that is a problem because recursion is essential and not an afterthought - we won’t commit to a proving system that can’t meet our extremely tight recursion requirements.

Luckily there are some candidates, and the Ethereum Foundation is doing trailblazing work as one of the few teams that has started to take this problem seriously.

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Getting larger proofs through the network

Proof size matters because Aztec transactions travel through a peer-to-peer network. Every node that receives and forwards a proof pays its bandwidth cost. Aztec’s 20kb proofs are “ok”. If it ever becomes a bottleneck we can make them smaller with little effort because we use elliptic curves.

Post-quantum proof systems (the fast ones), on the other hand, have proofs of ~300KB, which is not ok.

Worse, there are zero post-quantum proving systems whose proofs are small enough to gossip across a p2p network whilst achieving acceptable transaction throughput. There are fundamental constraints which mean this is not likely to change!

Fast recursion offers another path. A node could receive two transaction proofs, produce one proof that establishes the validity of both, and forward the aggregate. Other nodes could repeat the process. Transaction data would still have to travel through the network, but the proof overhead could shrink across a batch.

Ethereum’s post-quantum research faces a related problem. Its proposed hash-based validator signatures lack BLS’s cheap native aggregation, so leanVM supplies a proof that many signatures pass verification. The draft EIP-8292 assigns that proving work to aggregators with suitable hardware. Their longer-term roadmap requires full virtual-machine proof aggregations which presents an extremely similar problem to ours.

For the Aztec approach to work on ordinary nodes, aggregation needs to be cheap. My working estimate is that two-to-one aggregation in roughly 20–100 milliseconds on a modern CPU could make it practical. 

Nodes receive different transactions at different times, so they will duplicate work. An attacker may try to exploit that duplication. We need to establish how many aggregations one malicious transaction can induce and what happens to throughput under that load.

This problem is currently under-explored and poorly parametrised and substantial work needs to occur before a definitive solution can be decided on.

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Which proving systems look promising?

The main candidates are hash-based systems over binary fields and small prime fields, lattice-based systems, and proposals that combine both prime-field and binary-field representations.

The Flock paper gives a good example of the progress in binary-field proving. Its authors report proving 660,000 BLAKE3 hashes per second on an M4 mac on ten cores. 

These are impressive numbers. Hashing is a major part of verifying hash-based proofs, so cheap hashing is good for recursion.

However, binary field systems are weak with regards to integer multiplication. Trustless access to Web2 data is one of the biggest untapped capabilities of blockchain. Private applications should be able to use passport signatures, credit credentials, TLS-based data proofs and signed web tokens without publishing the underlying information. That means dealing with ugly Web2 cryptography: RSA, large-field elliptic curves and integer arithmetic.

Binary-field arithmetic does not behave like integer arithmetic. In particular, integer addition has carries, and multiplication needs a representation and a circuit that handles them. A BLAKE3 benchmark tells us little about the cost of proving a 4096-bit RSA verification. We need to measure the operations our applications will use.

That is what makes hybrid approaches interesting to me: using one commitment both in a binary representation and a prime field representation depending on context. This is an active area of research with limited existing published work, which highlights how rapidly evolving this space is.

Lattice-based proving deserves serious attention too. The Jolt team’s September release replaced the elliptic-curve commitment scheme Dory with Akita, based on Module-SIS. The authors reported faster proving and verification and proofs below 100 KB. Their announcement also described zero knowledge as forthcoming, so those figures do not settle our comparison.

Lattice commitments retain algebraic structure that could be useful for the kinds of composition we rely on. That makes them attractive candidates to investigate, although translating CHONK’s techniques would require work. The field size is a design choice we need to evaluate within each construction; lattices do not impose one universal 128-bit-field requirement.

Much of the suspicion around lattice systems rests on vibes about whether the underlying structure is vulnerable to AI cryptoanalysis. There are good reasons to scrutinize a particular assumption, parameter set or reduction. “It uses lattices” does not supply that scrutiny.

Not all lattice crypto is equal. The fundamental short-integer-solution hardness assumption has had decades of cryptanalysis. Lattice crypto has a degraded reputation because some modern protocols layer on additional, weaker hardness assumptions that have shown to be broken by quantum adversaries. But there is no quantitative evidence to suspect the core harness assumptions of lattice crypto are vulnerable.

Either way, the rate of development gives me confidence that we will have good options. It also makes choosing a winner today premature. We need comparisons that include our applications, recursion, zero knowledge and security parameters together.

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Signatures

In Aztec transactions, digital signatures are private witnesses within private functions of smart contracts (zero-knowledge circuits), which helpfully means we don’t care so much about the size of an individual signature. This gives us more freedom than non-rollups e.g. Ethereum, where signature size directly contributes to their transaction size. This matters because post-quantum digital signatures are typically large.

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Baking Bad

Similar to other privacy protocols such as ZCash Sapling and Orchard, several Aztec keys are baked-into the preimage of an Aztec address. To enable ‘post-quantumification’ of the Aztec protocol, we’re exploring externalising those keys to a canonical keystore registry. An Aztec address would then cease to be an elliptic-curve public key, and instead would simply be a hash which serves as a lookup into this registry. The registry could store all manner of exotic post-quantum public keys for different use cases.

Hash functions belong in the migration too

Aztec uses Poseidon2 throughout the protocol. Poseidon2 is technically post-quantum secure. And while Poseidon2 is secure for our chosen domain, recent breaks over small-field Poseidon signal that we should move to a different hash function in the long-term.

We’re confident that Poseidon2 will remain practically secure for many years, but the writing is on the wall and it would not be wise to use this hash function in Aztec’s future post-quantum system. 

We will likely replace it with either Blake2s or Blake3. The Ethereum Foundation are also considering a canonical hash function for their post-quantum roadmap and we’ll more than likely follow their lead here. Binary-field proof systems can trivially handle BLAKE hashes so the need for Poseidon2 will have run its course.

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Why the roadmap extends to 2030

Our proposed selection milestones are:

  • March 2027: choose a post-quantum signature scheme.
  • July 2027: choose a post-quantum public-key encryption scheme, with constrained note delivery benchmarked in the leading proof systems.
  • November 2027: choose a post-quantum proving system.

The encryption milestone needs circuit measurements before we settle the proving-system choice. The proving-system decision needs working recursion and zero knowledge, alongside representative application workloads. These dates give us a sequence for answering those questions.

After selection, we need to replace the cryptography across the system. That includes addresses and key derivation, application-specific key checks inside the kernels, account authentication, validator authentication and the proof chain that ends on Ethereum. We also need to handle existing private state and give users and applications a migration path.

Ethereum supplies another dependency. Aztec’s final proof verification and blob commitments sit within Ethereum’s cryptographic infrastructure. A full post-quantum migration has to account for Ethereum’s upgrades as well as our own.

The roughly three years between the final selection milestone and end of year 2030 leave room for integration to expose problems that isolated benchmarks cannot. Development and integration of multiple novel post-quantum cryptographic primitives into Aztec will be neither simple nor fast. In addition, the entire tech stack will have to be formally verified due to the incredible threat that AI poses with regards to finding and exploiting bugs.

I think Q-day within four years is unlikely, and the roadmap is designed under the assumption that post-quantum work is not the sole focus and obsession of the Aztec Foundation. If there is evidence of faster progress in quantum hardware that would bring forward Q-day, we will be able to accelerate our roadmap by diverting resources to this project.

Developers will not have to wait for that full migration to make better choices about private data. The January work will provide hardened libraries and documented patterns to build against. A developer building a private application will be able to protect the data they create today to stand the test of time.

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.

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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.

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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.

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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.

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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.

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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

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Source and docs

Aztec Network
Aztec Network
22 Jul
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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.