Last updated 2 months ago
The Cardano ecosystem lacks support for the EUDI credential verification, hindering seamless KY, and privacy-preserving identity checks for regulated dApps in Europe.
EUDI4Cardano employs zk-SNARK proofs from an off-chain, trustless endorser service to enable Cardano smart contracts to verify EUDI credentials, ensuring compliance and user privacy.
This is the total amount allocated to EUDI4Cardano – Interoperability of EUDI Wallets with Cardano.
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Please provide your proposal title
EUDI4Cardano – Interoperability of EUDI Wallets with Cardano
Enter the amount of funding you are requesting in ADA
100000
Please specify how many months you expect your project to last
7
Please indicate if your proposal has been auto-translated
No
Original Language
en
What is the problem you want to solve?
The Cardano ecosystem lacks support for the EUDI credential verification, hindering seamless KY, and privacy-preserving identity checks for regulated dApps in Europe.
Supporting links
Does your project have any dependencies on other organizations, technical or otherwise?
Yes
Describe any dependencies or write 'No dependencies'
Mainly depending on the changes to the EUDI wallet as specified in the Architecture Reference Framework (ARF), which, however, is not expected to introduce drastic changes as it is already being adopted by public and private sectors in the European member states.
Will your project's outputs be fully open source?
Yes
License and Additional Information
Apache-2.0 license – all code, proof-of-concept, and final implementation will be released as open source.
Please choose the most relevant theme and tag related to the outcomes of your proposal.
Identity & Verification
Describe what makes your idea innovative compared to what has been previously funded (whether by you or others).
EUDI4Cardano is the first initiative to make the European Digital Identity (EUDI) wallet interoperable with the Cardano ecosystem. Earlier Cardano identity projects focused on self-sovereign/anonymous credentials, but none enabled legally accepted, government-issued credentials usable on Cardano. Our approach combines zk-SNARKs with verification of EUDI credentials, letting Cardano dApps enforce KYC compliance while preserving privacy. This bridges EU-wide digital ID infrastructure with Cardano dApps and could give the network a unique regulatory edge over other blockchains.
Describe what your prototype or MVP will demonstrate, and where it can be accessed.
Our MVP shows end-to-end flow: a user presents an EUDI credential via an off-chain endorser, which generates a zk-SNARK proof binding it to a Cardano address. The proof is verifiable by a smart contract without exposing personal data, ensuring the address holder is a natural person with a valid EU credential. Prototype includes: (1) Endorser with OpenID4VP, SD-JWT verification, zk-SNARKs. (2) Cardano contract verifying proofs. (3) Demo contract offering services to EU persons over 18.
Describe realistic measures of success, ideally with on-chain metrics.
Technical success metrics: (1) User experience throughout the whole flow of registering a Cardano address as being connected to an EUDI credential. (2) The efficiency of the proof generation and verification times, the latter of which have to be feasible regarding on-chain execution costs. (3) Provision of open-source code with comprehensive documentation and reproducible test cases.
Adoption and ecosystem metrics: (1) At least one demo dApp live on the Cardano testnet. (2) Community adoption measured by GitHub stars, forks, and developer feedback.
Please describe your proposed solution and how it addresses the problem
The European Digital Identity (EUDI) wallet, as mandated by the recent eIDAS 2.0 regulation, will enable approximately 450 million EU citizens to hold government-issued, legally recognized verifiable credentials by 2026. These credentials will serve as a foundation for trusted digital identity across a wide range of services both in public and private sectors. They will also play a key role in financial transactions and in ensuring compliance with regulatory requirements such as the Markets in Crypto-Assets Regulation (MiCA)
However, Cardano’s current ecosystem lacks native support for directly verifying these EUDI credentials within smart contracts. This lack of interoperability may create a critical barrier to widespread adoption of Cardano in Europe’s emerging regulated digital economy. Without this capability, decentralized applications (dApps) such as decentralized exchanges, lending platforms, and gaming services cannot reliably use EUDI credentials for identity verification purposes.
In practice, this results in ineffective compliance workflows. For example, MiCA requires that crypto asset transfers only occur to addresses controlled by identities that have passed rigorous KYC checks. Today, exchanges often rely on users to self-certify ownership of withdrawal addresses without any cryptographically verifiable proof. This shifts legal risks onto users and undermines regulatory confidence.
Technically, the core problem is that Cardano’s smart contracts currently do not support the OpenID for Verifiable Presentation (OpenID4VP) protocol as used for EUDI wallets. Nor can they verify EUDI credentials, which correspond to Selective Disclosure JSON Web Tokens (SD-JWT). Verification of such tokens also involves retrieving information about the credential issuer using a TLS connection. As a result, EUDI users cannot directly present their EUDI credentials on-chain, and Cardano contracts cannot verify these credentials without off-chain support.
This situation creates several unmet needs:
To address these challenges, our project, EUDI4Cardano, introduces a solution that enables Cardano smart contracts to verify EUDI credentials via succinct zero-knowledge proofs (zk-SNARKs), without exposing sensitive personal information to the public. By bridging the gap between the upcoming EUDI wallet standard and Cardano smart contracts, EUDI4Cardano empowers decentralized applications to leverage legally recognized government-issued credentials for identity and age verification, KYC compliance, or other regulatory requirements.
At the core of our approach is an off-chain, non-trusted endorser service that interacts with users holding an EUDI wallet. The endorser performs the OpenID4VP presentation protocol, verifies the SD-JWT-based credential according to the specifications, and generates a zk-SNARK proof attesting to the validity and ownership of the credential bound to a specific Cardano address. Importantly, the endorser service does not need to be trusted: correctness relies solely on zk-SNARK verification, and through minimal disclosures, the endorser learns no sensitive credential attributes.
These proofs can then be efficiently verified on-chain by Cardano smart contracts, enabling privacy-preserving identity verification and potentially ensuring compliance with regulations such as MiCA, including sanctions screening.
The solution is structured around four key components:
Finally, we aim to design the solution in a way that allows direct integration with Veridian’s ID wallet or provides clear guidance for such integration, ensuring seamless use of EUDI credentials across Cardano applications.
By implementing EUDI4Cardano, we bridge the gap between Europe’s legally recognized identity framework and Cardano’s decentralized ecosystem, unlocking regulatory acceptance and enabling a broad range of compliant, privacy-preserving services.
Please define the positive impact your project will have on the wider Cardano community
EUDI4Cardano will deliver long-term value to the Cardano ecosystem by enabling trustless, privacy-preserving, and legally compliant identity verification on-chain for European citizens. By bridging the European Digital Identity (EUDI) wallet with Cardano, we position the ecosystem to thrive in Europe’s emerging regulated digital economy.
Through zk-SNARK-based verification of EUDI credentials, decentralized applications can securely verify a user's identity without relying on centralized intermediaries. This unlocks new categories of dApps such as decentralized exchanges, lending protocols, and gaming services that can integrate regulatory compliance directly into smart contracts while preserving user privacy.
By providing native support for EUDI credentials for Cardano, we also lower barriers for adoption by European institutions, businesses, and developers who require legally recognized identity standards. This strengthens Cardano’s competitiveness against other blockchain ecosystems that may otherwise capture Europe’s regulated markets.
Beyond immediate use cases, the open-source code, and integration guidelines produced by this project become reusable infrastructure for the entire developer community. Future teams building identity-focused dApps will benefit from documented components for proving and verifying SD-JWT based credentials instead of rebuilding core functionality from scratch.
In the long term, EUDI4Cardano will help position Cardano as the blockchain of choice for privacy-preserving, regulation-ready digital identity support in Europe, fostering growth in both institutional adoption and user trust.
What is your capability to deliver your project with high levels of trust and accountability? How do you intend to validate if your approach is feasible?
The PolyCrypt GmbH is a spin-off of the Technical University of Darmstadt, Germany with former members of the applied cryptography research group. Core areas include the research and development of Layer 2 interoperability and scaling solutions such as Perun State Channels as well as security and privacy solutions for decentralized identities such as threshold cryptography. Currently, PolyCrypt employs 12 people with different backgrounds in cryptography and software engineering. In the project the following team members will be involved:
We have already successfully completed two projects funded by Cardano, namely “Perun Channels for Cardano” in F8 (https://cardano.ideascale.com/c/idea/400079)))) and more recently, “Easily recoverable Identity Wallets for Atala Prism (SSI Threshold Wallets)” in F11 (https://projectcatalyst.io/funds/11/cardano-open-developers/easily-recoverable-identity-wallets-for-atala-prism-ssi-threshold-wallets)..)..)) Notably, the latter project helped us to deepen our expertise in digital identities in the Cardano ecosystem.
Milestone Title
Research & Proof of Concept
Milestone Outputs
Research on recent zk-SNARK optimizations for efficient ECDSA verification (such as by Google and Microsoft), and suitable backends (Groth16, Plonk, Ligero) for proving - , verification cost, and proof size. Write a report of this analysis and recommendations for a secure and efficient circuit for SD-JWTs based on ECDSA.
Acceptance Criteria
Research report analyzing zk-SNARK backends and various optimizations and for verifying SD-JWT credentials based on ECDSA.; clear recommendations; minimal PoC circuit demonstrating feasibility of credential verification with simplified assumptions.
Evidence of Completion
Published research report and a GitHub repository with the PoC zk-SNARKs circuit code for verifying a simplified SD-JWT credential.
Delivery Month
1
Cost
13000
Milestone Title
Trusted Endorser Prototype
Milestone Outputs
Implement a first trusted endorser service supporting the OpenID4VP protocol and SD-JWT verification but without any zk-SNARK computation. Upon successful verification, it generates an “endorsement” signature for a given user Cardano address. Additionally includes a Plutus smart contract for on-chain verification of the endorsement signature.
Acceptance Criteria
Users can present valid EUDI credentials using their EUDI wallet through the endorser. The endorser service issues signatures for the users’ Cardano address. The Plutus smart contract verifies the endorsement signature.
Evidence of Completion
GitHub repository with the endorser service code and Plutus smart contract including a short tutorial; demo video showing full flow; documentation of protocol steps.
Delivery Month
3
Cost
27000
Milestone Title
zk-SNARK Circuit Implementation
Milestone Outputs
Develop zk-SNARK circuits for verifying EUDI SD-JWT credentials and integrate circuits into the endorser. Let the endorser generate succinct proofs binding to a Cardano address without any additional trusted assumptions.
Acceptance Criteria
Endorser’s circuit verifies SD-JWT credentials and outputs a zk-SNARK proof. Proof verification supported by updated Plutus contract. Credential checks such as revocation are omitted because of infeasibility in zk-SNARKs.
Evidence of Completion
GitHub repository with updated endorser service including zk-SNARK circuits and updated Plutus contract. A demo app verifying proofs on-chain.
Delivery Month
5
Cost
35000
Milestone Title
Integration & Documentation
Milestone Outputs
Integration guide for the Veridian ID wallet and its ecosystem; full documentation covering architecture, implementation, usage. A demo dApp showing a practical use case such as identity verification for cryptocurrency trades.
Acceptance Criteria
Guide to enable Veridian wallet to support EUDI wallets and seamless interaction with the endorser service. Developers can follow documentation to use the endorser zk-SNARK proofs with Cardano contracts. Demo app runs end-to-end scenario. Complete technical documentation.
Evidence of Completion
Delivery Month
7
Cost
25000
Please provide a cost breakdown of the proposed work and resources
The entire budget is allocated to engineering and execution, i.e., no funds go to marketing, or unrelated expenses. Costs are calculated based on personnel effort (research, engineering, architecture, testing, project management), infrastructure needs, and validation activities.
Project Management & Delivery Coordination: ~5% Ensuring milestone delivery, developer documentation, and ecosystem alignment (carried out by project manager).
M1: Research & Proof of Concept
Duration: 1 mo
Cost: 13.000 ADA
Ressource Allocation: Research on zk-SNARK optimizations, PoC circuit development
M2: Trusted Endorser Prototype
Duration: 3 mo
Cost: 27.000 ADA
Ressource Allocation: Endorser service with OpenID4VP, Plutus contract implementation
M3: zk-SNARK Circuit Implementation
Duration: 3 mo
Cost: 35.000 ADA
Ressource Allocation: zk-SNARK circuit development, integration with endorser
M4: Integration & Documentation
Duration: 2 mo
Cost: 25.000 ADA
Ressource Allocation: Integration guide, documentation, demo dApp development
Total
Total duration: 7 mo
Total cost: 100.000 ADA
Ressource Allocation: 100% allocated to engineering & delivery
Note that several of the tasks outlined above will run in parallel, and the project is scheduled to conclude seven months after its start.
How does the cost of the project represent value for the Cardano ecosystem?
The total project budget of ~100.000 ADA is fully allocated to research, engineering, and execution - ensuring that every ADA directly contributes to proper research and the development and integration of the proposed EUDI4Cardano solution advancing the interoperability between Cardano and legally recognized digital identities.
This investment produces:
The cost-to-impact ratio stands out due to the creation of versatile, reusable components rather than isolated solutions. Future Cardano developers working on identity-focused dApps will gain significant advantages, bypassing the need to reinvent core infrastructure such as zk-SNARK circuit designs. With a focus on enduring ecosystem benefits, broad applicability across sectors, and an open-source approach, this project guarantees that every ADA invested drives sustained value through enhanced developer engagement, user expansion, and greater ecosystem variety.
Terms and Conditions:
Yes
The PolyCrypt GmbH is a spin-off of the Technical University of Darmstadt, Germany with former members of the applied cryptography research group. Core areas include the research and development of Layer 2 interoperability and scaling solutions such as Perun State Channels as well as security and privacy solutions for decentralized identities such as threshold cryptography. Currently, PolyCrypt employs 12 people with different backgrounds in cryptography and software engineering. In the project the following team members will be involved:
Sebastian Faust: Professor of Computer Science at Technical University of Darmstadt and research lead and co-founder at PolyCrypt
Philipp-Florens Lehwalder: Cryptographic researcher at Technical University of Darmstadt and PolyCrypt
Hendrik Amler: Project manager and co-founder at PolyCrypt
Jens Winkle: Cryptographic engineer and software developer at PolyCrypt
We have already successfully completed two projects funded by Cardano, namely “Perun Channels for Cardano” in F8 (https://cardano.ideascale.com/c/idea/400079)) and more recently, “Easily recoverable Identity Wallets for Atala Prism (SSI Threshold Wallets)” in F11 (https://projectcatalyst.io/funds/11/cardano-open-developers/easily-recoverable-identity-wallets-for-atala-prism-ssi-threshold-wallets)..) Notably, the latter project helped us to deepen our expertise in digital identities in the Cardano ecosystem.