TL;DR

• The city of Buenos Aires has rolled out ZK-backed digital identities to all of their citizens (~3.6m).

• Leading the way in data privacy and citizen empowerment, Buenos Aires has become the first government to leverage blockchain and zero-knowledge cryptography for digital identity management enabling citizens to verify their identity (and other attributes of citizenship) without having to expose any PII.

• The update to the miBA application comes with nearly 60+ documents (such as birth certificates, citizen credentials, and more) now accessible to denizens of the capital city to access their government portals, process documents, receive birth certificates and marriage licenses, and open the door to digital sovereignty for citizens.

• The government of Buenos Aires becomes the world’s first government to hand off ownership of digital credentials to residents. These credentials are emitted to an individual, and upon receiving them the government no longer has any visibility into how, where, or when these identity documents are used.

Today, the Government of the City of Buenos Aires announced the integration of QuarkID, a ZKsync-powered decentralized identity solution, into its miBA platform. This groundbreaking initiative makes Buenos Aires the first city worldwide to implement blockchain and zero-knowledge cryptography for creating self-sovereign digital identities. By empowering 3.6 million residents with enhanced control over their personal data, the city sets a new standard in privacy and security for digital identity management. All governments own their citizens’ data, Buenos Aires is the first to relinquish control.

Starting in October of 2024, all active users of miBA, the city's digital platform for accessing government services and documents, received their own decentralized digital identity (DID). These DIDs are secured by QuarkID's wallet and settled on Era, a Layer 2 blockchain powered by ZKsync. This initiative positions Buenos Aires as a pioneer in transforming government services through blockchain technology, setting a new global standard for privacy-focused digital identity.

For blockchain to scale, we need to ‘hide the wires’. While infrastructure and technology are summarily important, the benefits they give to individuals are what is most important. The technology should simply be better, safer, and more private than the alternative. When you ask an average citizen if they’ve used email, nearly everyone will say yes. If you ask that same group how many of them have heard of TCP/IP, then a very small percentage will claim they have. If you ask them how it works, an even smaller number of people will be able to articulate the basics. In Web3, there is too much emphasis on the underlying technology.

Buenos Aires is leading the way to future mass adoption by taking their existing centralized identity solution, named miBA, and replacing the backend with QuarkID. QuarkID is a decentralized, open-source, digital public good that offers digital identity and a trust framework, powered by ZKsync Era in order to deliver privacy, security, and scalability for citizens and the government alike.

Overnight, 3.6m citizens have had their credentials upgraded to being blockchain based – which greatly enhances security and interoperability amongst other benefits – without the individuals needing to be informed on the necessity for blockchain or zero-knowledge cryptography. No seed phrases needed. Users simply see an improved application that offers updated features, new credentials, greater usability, shortens their wait times, and reduces the amount of government tasks they need to do in person. Now they can do everything from receiving tax benefits to proving education status, all from the convenience of their laptops and mobile devices.

Empowering Citizens with Ownership and Control

In a world where governments and institutions traditionally own and manage citizens' data, Buenos Aires is turning the model upside down by giving citizens direct ownership of their personal information. Through QuarkID, individuals can now access, store, and share their verified credentials — like birth certificates or tax documents — securely and independently.

This self-sovereign identity (SSI) approach gives citizens control over their personal data. Rather than relying on physical documents that expose unnecessary information, such as a full name or address when proving one's age, residents can now verify their credentials peer-to-peer through their mobile devices. This guarantees that no third party, including the government, can track when, how, or why a credential is being used. This is distinct from existing centralized identity platforms where governments have complete oversight into how and when digital identities are accessed and verified. In Buenos Aires’ case, by using QuarkID, all verifications are P2P which ensures that the government is not alerted when citizens use their credentials.

Jorge Macri, Chief of Government of the City of Buenos Aires, commented on the news: “The incorporation of zero-knowledge blockchain technology into the City's digital identity system is an unprecedented milestone that positions us globally as a leader and once again demonstrates that the City of Buenos Aires is at the forefront of innovation. Adopting new technologies that simplify citizens' processes while giving them full control over their information is a fundamental step toward continuing to offer more secure and transparent digital solutions."

The Benefits of Decentralized Identity

At the core of this initiative is QuarkID’s open-source digital trust framework powered by ZKsync’s zero-knowledge proof blockchain technology, which brings a new level of security, privacy, and transparency to how personal data is managed:

• Privacy and Zero-Knowledge Proofs: With QuarkID powered by ZKsync Era, citizens can verify the accuracy and authenticity of their credentials without ever exposing their personal data. Through zero-knowledge proofs, only the necessary information is revealed — for instance, confirming an individual’s age without disclosing their full birthdate, address, or document number. This ensures maximum privacy while maintaining verifiable accuracy.

• Ownership and Control: Citizens now have full custody over their digital credentials, stored securely on their mobile devices and protected by biometric encryption. They are no longer reliant on centralized systems that retain and manage their data on their behalf, significantly reducing the risks of data breaches and identity theft. Citizens can simply share a ‘proof’ of their identity to access benefits, applications, bank accounts and more in the future without risking additional exposure of their data.

• Security and Immutability: ZKsync’s decentralized architecture adds an additional layer of security. Proof of citizen's personal credentials are settled on chain not stored in a centralized database, making them far less vulnerable to cyberattacks. Instead, the verification of these credentials occurs through a secure peer-to-peer system, with zero-knowledge proofs ensuring that no personally identifiable information (PII) is ever exposed.

• Open Source and Scalable: QuarkID’s architecture is open-source and has been recognized as a Digital Public Good (DPG) working towards achieving the Sustainable Development Goals (SDG) set by the United Nations. By making it accessible to cities, governments, and private enterprises across Latin America and beyond, this framework is designed to scale, encouraging banks, sports teams, artists, and businesses to adopt QuarkID and offer secure login solutions for citizens with endless possibilities. Opening doors for new use cases such as providing exclusive benefits for citizens of a region, including loyalty programs or discounts for verified users.

“We’ve seen a lot of blockchain-based innovation in financial services, but this initiative demonstrates the power of blockchain to revolutionize other uses cases such as government services by empowering citizens to safely and securely own their data,” said Diego Fernandez, Secretary of Innovation and Digital Transformation of the City of Buenos Aires. “By giving residents control over their identities, we’re not only improving privacy and security, but we’re also setting the foundation for a future where personal data ownership is a basic right, protected by advanced zero-knowledge-based cryptographic proofs.”

How Does QuarkID Work?

How does the current implementation of Digital Identity from the City of Buenos Aires operate?

• The government already has citizen information stored securely.

• The government will now create a Decentralized Identifier (DID), which is an indecipherable alphanumerical string, which acts as a unique and verifiable piece of information that will be hosted on chain.

• In this case, the DID is stored on ZKsync Era which can leverage the benefits of ZK technology, allowing citizens to prove information is true, without disclosing the underlying information.

• No Personally Identifiable Information (PII) is ever stored on ZKsync.

• QuarkID follows the W3C standard for interoperability of digital identities, so this framework adheres to the globally-respected standard.

• This ZK proof is how a user and verifier can securely and safely verify information without exposing any data. Its security and immutability protect against identity theft and data tampering.

QuarkID: Present and Future

Since the initial announcement of QuarkID in September 2023, Buenos Aires has worked closely with partners such as Extrimian to transition miBA’s centralized system to a decentralized one. QuarkID allows residents to view, download, and share documents while also serving as the login portal for all government systems to schedule appointments, carry out procedures, or submit requests. Citizens can now access any of the City’s systems (previously miBA login) by simply scanning a QR code—no password required.

With the integration of QuarkID, miBA users will have access to over 60 digital documents and certificates, including but not limited to:

• Birth, marriage, and death certificates

• Student certificates

• Vaccination certificates

• Gross income tax certificates

• Citizen credentials

In the coming months, additional documents, such as driver’s licenses, public space permits, and high school diplomas, will be added. This innovation will also allow users to add credentials from other organizations that adopt the QuarkID protocol, enhancing the platform’s versatility and usability.

Upcoming Use Cases for ZK-Powered Digital Identity

QuarkID enables the superpower of being able to prove an individual is 1. Who they say they are 2. Is from a specific region/country 3. Has their credentials and information up to date. With these items as ‘provable’, QuarkID opens the doors for many new government and business-specific applications that were difficult, if not impossible, before.

Verified benefits for citizens of a certain region

• If you knew an individual was from a city, state, region, or country - what benefits could you offer?

  • An example is a concert like Lollapalooza Argentina could offer discounted drinks or quicker accesses into the festival for citizens of the home country.

  • An airport can give preferential access to verified citizens, without any additional programs or application processes.

  • FIFA could prove an individual is from 1 country only, and be able to offer preferential ranking in the World Cup Ticket Lottery.

Safer interaction with government officials

• In the near future, police officers in Argentina will have a verifier - which is simply a QR code which an individual scans.

  • An individual is prompted to share documents pending their approval.

  • In this case, an officer may ask for a driver's license, vehicle registration, and insurance.

  • Instead of opening the glove box and searching for these documents, sharing unnecessary PII to the individual officer, and risking issues during the interaction, the individual simply scans the QR, approves the request, and when it’s approved the officer will simply see a green checkmark which approves the interaction and allows the driver to be on their way.

Voting

• Through QuarkID, governments can prove that a citizen is verified and eligible to vote. This framework can provide the most important step to enabling digital voting which is proving humanity + citizenship, ensuring double-blind voting while ensuring that results are auditable and publicly verifiable.

Sports Affiliations

• Soccer teams can know who their true fans are and offer them exclusive benefits. The team can verifiably prove that an individual only has a credential for their club, and can allow a user to opt-in to share information about their attendance to qualify for exclusive benefits, discounts, and rewards.

• Which ‘club’ in Argentina really has the most fans? Through verified citizenship + opting into a specific team, soccer teams could have a public dashboard which is auditable to prove who has the most ‘hinchas’.

Loyalty

• Artists can reward their true fans and prove their affiliation, issuing credentials as concert tickets and having fans verify their past attendance to access exclusive events.

• Movie theaters can create a verified affiliates program, where citizens can access benefits without being subjected to spam or having their emails leaked due to limited opsec.

Banks

• Banks will be able to leverage citizen credentials to KYC clients. By being able to prove someone is a resident/citizen, and verify their information, citizens will be able to safely open a bank account with one click.

• Businesses can also be registered and verified for a range of products from the bank. While Buenos Aires is leading with citizen credentials, there are already pilot’s live across Latam using the same infrastructure for businesses to open bank accounts, receive notarized approvals for licenses and more.

Previous Implementations of Digital Identity

Currently there have been a range of Digital Identity platforms released globally. Some are government backed and issued such as Aadhar in India, Sing Pass in Singapore, Eidas in Europe and more. These all adhere to the W3C standards, which ensures interoperability which QuarkID also is built upon. The difference between miBA’s implementation and the above is that the aforementioned Digital Identity Solutions are all centralized, meaning the governments not only have ownership and control, but also traceability and tracking lacking the transparency and sovereignty which a technology leveraging QuarkID does.

The above platforms, while far reaching, are at risk of being honey-pot attack vectors, which has been seen with repeated successful hacks of these systems. QuarkID by enabling decentralization + interoperability reduces these attack vectors through having multiple issuing bodies. Additionally, by leveraging zero-knowledge technology no PII is ever exposed through on chain activity. The immutable record only hosts DIDs, of which the underlying information is encrypted beyond reconstruction.

Other blockchain based identity systems, such as World Coin, operate in a different context. World Coin is incredible at proving a human is a human and there are no duplicates. However, these identities are not associated with any attributes like citizen data (which is issued by governments). So while Zero Knowledge technology is at play, the usability and adoption curves are quite different.

What’s Next for QuarkID?

Will QuarkID expand beyond Buenos Aires?

• Any city or organization can easily adopt the QuarkID protocol due to its open-source nature, allowing it to issue decentralized verifiable credentials secured by blockchain technology.

• Banking: Banks across Latam are in confirmed pilots, exploring use cases such as authentication, KYC, and access across the region.

• Healthcare: A range of public and private health companies are exploring the use of Verifiable Credentials to track health records, as well as registries such as organ donation.

• Sports: Sports organizations have been exploring access and loyalty benefits for their most dedicated fans.

• Elastic Chain Vision: As a part of the future expansion of QuarkID, there will be an Elastic Chain hosting digital identity and trust frameworks to ensure an interoperable digital identity across the Ethereum ecosystem, based on ZKsync technology.

How to get involved?

As an open-source Digital Public Good, QuarkID invites developers, enterprises, and institutions to contribute to its continued growth. The framework offers a secure, decentralized infrastructure that can be adapted for secure logins, identity verification, and even loyalty programs across various industries.

Developers: Contribute to QuarkID’s core protocol to help expand secure login capabilities for citizens. Learn more and get involved through the open-source codebase at the protocol’s GitHub. Integrate QuarkID into your project or solution - reach out to Extrimian to leverage their ID Connect APIs to simplify the process of integration and implementation.

Private Enterprises: Banks, sports teams, and businesses are encouraged to enable secure logins and offer exclusive benefits to verified citizens, helping build a more secure and engaging ecosystem for everyone.

Governments: If you’re looking to implement the most-trusted, permissionless Digital Identity framework be sure to get in touch with the team at Extrimian to explore how to implement ZK-backed Digital Identity for your citizens.

Citizens of Buenos Aires: If you’re a resident of the City of Buenos Aires, you can access miBA with QuarkID enabled today through iOS, Android or webapp and start owning your identity today. Many more credentials and benefits are coming down the line.

About miBA

miBA is the digital platform for accessing services and documents issued by the Government of Buenos Aires. Used by more than 3.6 million residents, miBA offers secure access to government services, document viewing, and management, all from a mobile app. Now, with the integration of QuarkID technology, miBA is taking a major step toward self-sovereign digital identity, giving citizens more control and security over their personal data.

About QuarkID

QuarkID is a digital protocol that implements a new trust framework for creating and managing digital identities and all their credentials in a decentralized manner, using asymmetric cryptography and the immutability of the blockchain to establish trust in a digital world. It is open-source and based on international standards such as those from W3C, Trust Over IP, and Decentralized Identity Foundation. It is designed to be interoperable with other protocols created around the world.

About Extrimian

Extrimian is a leading company in Latin America specializing in digital identity solutions on the blockchain. Its mission is to empower individuals and organizations through decentralized technologies that allow full control over digital identity and personal data.

About ZKsync

ZKsync leverages cutting-edge zero-knowledge (ZK) technology to create secure, scalable, and interoperable blockchain solutions. Through its ZK Stack framework, ZKsync enables developers, enterprises, and financial institutions to deploy customizable ZK Chains, forming the Elastic Chain ecosystem. This innovative network offers native, trustless interoperability, enhanced privacy, and unparalleled scalability while maintaining Ethereum's security. ZKsync's mission is to bring crypto to the mainstream, empowering millions of developers and billions of users with digital self-ownership and personal freedom. To learn more, visit zksync.io.