Last updated 5 months ago
The Identus ecosystem lacks a unified, feature-rich SDK, leaving .Net developers without the tools to build powerful, decentralized identity solutions and forcing complex workarounds.
Blocktrust will build a comprehensive, open-source .Net SDK for Identus, providing a unified toolkit for DID management, Verifiable Credentials, and secure DIDComm messaging, empowering .Net devs.
This is the total amount allocated to .Net Identus SDK.
Please provide your proposal title
.Net Identus SDK
Enter the amount of funding you are requesting in ADA
100000
Please specify how many months you expect your project to last
12
Please indicate if your proposal has been auto-translated
No
Original Language
en
What is the problem you want to solve?
The Identus ecosystem lacks a unified, feature-rich SDK, leaving .Net developers without the tools to build powerful, decentralized identity solutions and forcing complex workarounds.
Supporting links
Does your project have any dependencies on other organizations, technical or otherwise?
No
Describe any dependencies or write 'No dependencies'
No dependencies
Will your project's outputs be fully open source?
Yes
License and Additional Information
The project will be licenced under Apache 2.0
Please choose the most relevant theme and tag related to the outcomes of your proposal
Identity & Verification
Mention your open source license and describe your open source license rationale.
The .Net Identus SDK will be released under the Apache 2.0 License.
This license was chosen for several strategic reasons. First and foremost, it aligns perfectly with the "parent" project, Hyperledger Identus, which also uses the Apache 2.0 license. This ensures legal compatibility and removes any licensing friction for developers working within the broader Identus ecosystem. Furthermore, Apache 2.0 is a permissive, business-friendly license. For an SDK, this is crucial as it encourages the widest possible adoption. The license also includes an express grant of patent rights.
How do you make sure your source code is accessible to the public from project start, and people are informed?
From day one, the entire project will be developed in a public GitHub repository. All source code, commits, issues, and pull requests will be openly accessible, allowing anyone to track progress, review the code, and contribute.
To ensure the community is informed, the public repository link will be announced on the official Hyperledger Identus communication channels, such as their Discord server and community calls, as soon as a useable codebase is available.
How will you provide high quality documentation?
We will create and host a professional documentation website. This will be the central hub for all learning materials.
The entire public API will be thoroughly documented using C# XML comments. This enables IDEs like Visual Studio to provide developers with instant contextual help and IntelliSense, and serves as the foundation for an auto-generated API reference.
Please describe your proposed solution and how it addresses the problem
The current landscape for developers looking to build on Hyperledger Identus (formerly Atala PRISM) is fragmented. While powerful, the existing tools—a primary API-based agent written in Kotlin and Scala, alongside edge SDKs in Swift, TypeScript, and Kotlin with limited functionality—create a high barrier to entry. This cloud-agent-centric architecture often leads to inflexible solutions and forces developers into complicated workarounds for many common use cases. This is a challenge the Blocktrust team has faced many times when building on Identus in the past. The .NET SDK is therefore not just a theoretical idea but fills a tangible need.
The proposed solution is to develop a single, unified, and feature-complete .NET Identus SDK. This SDK will not be just another thin client for the cloud agent; it will be a standalone library that equips developers with all the necessary capabilities to build sophisticated decentralized identity applications from the ground up. By providing a familiar and idiomatic .NET experience, it will drastically lower the barrier for many developers to innovate within the Cardano ecosystem.
With the upcoming release of a new Lace wallet version in Q4, which will bring identity features to a mass audience, the timing for this SDK is perfect. It will provide the development community with the tools they need to build a new wave of identity-powered applications for this growing user base.
The SDK will be completely open-source under an Apache 2.0 license, ensuring it remains a community asset. It will implement a comprehensive set of features based on the latest open standards:
Think of this SDK as the essential toolkit that allows developers to stop wrestling with infrastructure and start focusing on their core value proposition of decentralized identity on Cardano.
Please define the positive impact your project will have on the wider Cardano community
This project will have a positive impact on the Cardano community, especially when the new Lace Wallet with identity features comes out and identity again takes a prominent role. By delivering a feature-rich .NET SDK, it will likely unlock a new pool of developer talent. The .NET ecosystem is one of the largest and most active in the world, and providing a first-class entry point could lead to more innovation, more applications, and wider adoption of Identus technology—and therefore also Cardano, as it functions as the underlying VDR (Verifiable Data Registry) for Identus.
The success of the project will be measured through a combination of quantitative and qualitative metrics.
Quantitative Metrics:
Qualitative Metrics:
The primary value proposition is acceleration. Projects will no longer need to build their own identity libraries from scratch or navigate the complexities of the fragmented capability mix between the Identus Cloud Agent and the different edge SDKs. This SDK will significantly reduce development time, cost, and complexity, allowing teams to focus on creating user-centric applications. This, in turn, can strengthen the entire Cardano network by fostering a richer, more diverse ecosystem of dApps and services that leverage secure, user-controlled digital identity.
All outputs, including the source code (Apache 2.0), documentation, and tutorials, will be shared openly from the start to ensure the entire community benefits from this foundational work.
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?
Blocktrust has been an active and dedicated participant in the Cardano ecosystem since early 2022, specializing in Self-Sovereign Identity (SSI) solutions using Atala PRISM (now Hyperledger Identus) from its very inception. Björn Sandmann has been working with the technology for over 3.5 years and has a deep understanding not only of the involved standards and technologies but of the overall SSI ecosystem. Over the lifetime of the Atala PRISM and now Identus projects, Björn Sandmann was heavily involved in many stages, giving feedback, being a Maintainer of the Identus project, helping in the process of moving it to Hyperledger, and interacting with IOG directly.
The Blocktrust team has successfully delivered 7 Catalyst-funded proposals, all focused on building out the identity infrastructure on Cardano. All projects have been completed and none are outstanding.
Our notable (open-source) contributions and projects include:
The Open PRISM Node (OPN): (https://bsandmann.github.io/OpenPrismNode/))
DIDComm Mediator: (https://mediator.blocktrust.dev)
Analytics Platform: (https://analytics.blocktrust.dev)
A collection of open-source libraries: (https://github.com/bsandmann)) e.g for Veriable Credentials or DIDComm communication.
Blocktrust has consistently delivered on its promises and maintained a nearly perfect record of successful deliverables. This deep, hands-on experience with the intricacies of the PRISM/Identus specifications means Björn is uniquely positioned to build this SDK efficiently and correctly, avoiding common pitfalls and ensuring a high-quality, production-ready outcome.
Milestone Title
Core Architecture and DID Management
Milestone Outputs
An initial alpha version of the SDK with a solid architectural foundation. This will include the core cryptographic libraries and full support for creating, updating, resolving, and deactivating In-Memory as well as using one of the existing Universal Resolvers and Universal Registrars.
Acceptance Criteria
The SDK can successfully perform all lifecycle operations for did:prism and did:peer according to the official specifications. The core cryptographic functions are implemented and covered by unit tests.
Evidence of Completion
A public GitHub repository containing the source code (inlcuding an Apache 2.0 licence)
An alpha version of the SDK published to a NuGet package registry.
A detailed progress report and technical overview.
The first (rough) pages of the Documentation site.
Delivery Month
4
Cost
25000
Progress
30 %
Milestone Title
Verifiable Credential (VC) Lifecycle Implementation
Milestone Outputs
An extended version of the SDK that supports the complete Verifiable Credential lifecycle. This includes the issuance and verification of JWT-based VCs, support for the privacy-enhancing Selective Disclosure (SD-JWT) format, and implementation of StatusList2021 for efficient credential revocation.
Acceptance Criteria
The SDK provides APIs to issue standards-compliant credentials, create verifiable presentations from those credentials, and verify incoming presentations. The implementation correctly handles SD-JWT disclosure and checks against a StatusList2021.
Evidence of Completion
An updated NuGet package.
An expanded test suite covering all VC lifecycle functionality.
A progress report with videos showcasing an end-to-end credential issuance and verification flow using the SDK. (Short and technical, but shoud prove that it is working).
New pages for the documentation and refinement of existing pages.
Delivery Month
8
Cost
25000
Progress
60 %
Milestone Title
Secure Messaging and Presentation Exchange
Milestone Outputs
A beta version of the SDK with a full implementation of DIDComm v2 for secure messaging. This includes support for establishing connections via Out-of-Band (OOB) invitations and handling proof requests using the DIF Presentation Exchange (PEX) 2.0 standard.
Support for all relvant DIDComm v2 protocols also used by Identus.
Acceptance Criteria
The SDK can be used to establish an encrypted, authenticated DIDComm v2 channel between two parties using an OOB invitation. It can correctly parse a PEX request, construct a conforming presentation, and send it over a channel.
Evidence of Completion
An updated NuGet package.
A demonstration application or test suite showing a complete DIDComm interaction between two instances of the SDK.
A demonstration application or test suite showing the OIDC4VC.
New pages for the documentation and refinement of existing pages.
Delivery Month
11
Cost
25000
Progress
90 %
Milestone Title
Finalization, Documentation, and Community Release
Milestone Outputs
A production-ready, stable v1.0 release of the .Net Identus SDK which publicly available and can be simpled pulled into a project. This includes comprehensive developer documentation, tutorials, code samples to support the developer community.
Acceptance Criteria
The SDK's public API is stable and well-documented.
The official documentation website is live and contains getting-started guides, tutorials, and full API references.
The v1.0 package is published to NuGet.
Evidence of Completion
A final project completion report.
A link to the official documentation website.
A link to the repo.
A link to the 1.0 package to be downloaded.
Delivery Month
12
Cost
25000
Progress
100 %
Please provide a cost breakdown of the proposed work and resources
The total requested budget is 100,000 ADA. This funding is primarily allocated to cover the development effort required to build, test, and document the SDK over a 12-month period.
Developer Costs:
The project is estimated to require approximately 20 hours of development work per week for 12 months (on average 2,5d/week). Based on a highly competitive, below-market rate of $80 USD per hour for the specialized expertise, the total development cost is:
20 hr/week * 52 weeks * $80/hr = ~$83,200 USD
Infrastructure, Tooling & Hosting Costs: A small budget is allocated for hosting the documentation website, running continuous integration pipelines, and maintaining test infrastructure for the duration of the project and beyond.
$100 USD/month * 12 months = $1200 USD
Total Project Cost: ~$84,400 USD
At an approximate exchange rate of $0.84 USD/ADA, this translates to the requested 100,000 ADA.
How does the cost of the project represent value for the Cardano ecosystem?
The cost is an investment in foundational infrastructure that will yield returns many times over by enabling new projects and developers.
Björn Sandmann's deep and long-standing expertise with Identus/PRISM is a critical factor. The project can be executed with an efficiency that would be impossible for a team new to the ecosystem. He has already navigated the learning curve, understands the specifications intimately, and can begin development immediately. This eliminates wasted time and ensures the funds are used effectively to produce a high-quality output.
The value is not just in the code itself, but in the multiplier effect it will create. By empowering the entire .NET developer community, it fosters an environment for innovation.
Finally, the cost is calculated using a below-market rate of $80 USD per hour to demonstrate a commitment to the Cardano ecosystem. By denominating the budget in ADA, we are aligning our success with the success of the ecosystem and personally taking on the downside risk of price volatility, a commitment demonstrated by consistently delivering on past projects, even during bear markets.
Terms and Conditions:
Yes
Björn Sandmann (Lead developer): 12+ years of full-stack development with the .NET Stack. Focused on identity and privacy solutions. PRISM Pioneer, Atala ASTRO, Plutus Pioneer, and has led 7 successfully funded & finished Catalyst proposals. Implemented the core technical functionality of many Blocktrust products. Founder of Blocktrust and a past member of the Governance Committee for the Hyperledger Lab for the Open Enterprise Agent (PRISM agent), Trust over IP, and DIF.
LinkedIn: https://www.linkedin.com/in/codedata/
GitHub: https://github.com/bsandmann
Extended Team: Björn Sandmann is supported by other Blocktrust collaborators like Ed Eykholt and John Ndigigiri, who have contributed to past successful Catalyst projects. While they are not directly part of this proposal, they will likely contribute in advisory and testing roles.