ZKMail: Confidential Zero-Knowledge On-Chain Messaging PoC

[Proposal setup] Proposal title

Please provide your proposal title

ZKMail: Confidential Zero-Knowledge On-Chain Messaging PoC

[Proposal Summary] Time

Please specify how many months you expect your project to last

3

[Proposal Summary] Translation Information

Please indicate if your proposal has been auto-translated

No

Original Language

en

[Proposal Summary] Problem Statement

What is the problem you want to solve?

Most blockchains expose all data, preventing private messages. ZKMail showcases a Midnight PoC with Zero-Knowledge messaging for secure, private, accountable on-chain messages.

[Proposal Summary] Supporting Documentation

Supporting links

• https://github.com/vumotions/zkmail

[Proposal Summary] Project Dependencies

Does your project have any dependencies on other organizations, technical or otherwise?

No

Describe any dependencies or write 'No dependencies'

No dependencies

[Proposal Summary] Project Open Source

Will your project's outputs be fully open source?

Yes

Please provide here more information on the open source status of your project outputs

ZKMail will be fully open source under the MIT License.

• All code for the messaging module, smart contracts, and the PoC will be publicly available.
• Developers can freely review, modify, and reuse the code.
• This ensures transparency, community collaboration, and supports future privacy-preserving dApp development on Midnight.
• Documentation and setup guides will be included to help others deploy and extend the PoC.

[Theme Selection] Theme

Please choose the most relevant theme and tag related to the outcomes of your proposal

Privacy

[Campaign Category] Category Questions

What is useful about your DApp within one of the specified industry or enterprise verticals?

Most blockchains expose all data, preventing private messaging and confidential proofs. ZKMail demonstrates a Zero-Knowledge messaging module via a Midnight PoC, enabling secure, private, and accountable on-chain messages. Organizations and communities requiring confidential communication, privacy-preserving workflows, or selective disclosure can use ZKMail to exchange messages while ensuring content and metadata remain hidden.

ZKMail allows users to:

• Send encrypted messages where only the intended recipients can decrypt the content.
• Verify the authenticity of messages and metadata using Zero-Knowledge proofs without revealing private data.
• Build accountability and traceability in sensitive workflows (e.g., DAO coordination, private proposals, or confidential notifications) while preserving privacy.
• By providing a privacy-first messaging layer, ZKMail enables broader adoption of Midnight for confidential communication, regulated digital collaboration, and decentralized communities requiring secure message verification.

What exactly will you build? List the Compact contract(s) and key functions/proofs, the demo UI flow, Lace (Midnight) wallet integration, and your basic test plan.

We will build a community-ready, open-source ZKMail PoC demonstrating end-to-end private messaging with ZK verification. The project includes:

Core Contracts:

• ZKMail messaging contract: handles encrypted message storage and delivery.
• Zero-Knowledge proof contract: validates messages and metadata without revealing content.
• Selective reveal logic: ensures only authorized recipients can decrypt messages.
• Optional ProfileNFT contract: anchors verified sender/recipient proofs for traceability without leaking sensitive info.

Community-Accessible UI:

• React frontend: Compose / Inbox / Sent interface with dark mode.
• Lace wallet integration: users can connect, sign, and send encrypted messages easily.
• Step-by-step workflow demonstrating sending, receiving, decrypting, and verifying messages.
• Admin / Community Tools (optional PoC features):
• Lightweight dashboard to visualize encrypted message flow.
• Demonstrates privacy-preserving verification of message delivery.

Tests and Examples:

• End-to-end test suite for smart contracts and frontend messaging flows.
• Example encrypted messages illustrating secure communication.
• Sample proof generation scripts showing ZK verification.

Documentation:

• Detailed walkthroughs for developers and community builders.
• Guides on building private messaging flows, generating ZK proofs, and selectively revealing content.
• Instructions for extending messaging module for DAOs, marketplaces, or community applications.

How will other developers learn from and reuse your repo? Describe repo structure, README contents, docs/tutorials, test instructions, and extension points. Which developer personas benefit, and how will you gauge impact (forks, stars, issues, remixes)?

Repo Structure:

• /contracts – ZKMail messaging contracts and proof logic.
• /ui – React frontend components and reusable messaging UI patterns.
• /docs – Architecture, setup guides, and tutorials for building private messaging workflows.
• /tests – Demonstrations of encrypted messaging and proof verification.
• /examples – Plug-and-play scripts for sending, decrypting, and verifying messages.

README & Tutorials:

• Quick-start setup guide using Midnight devnet and Glacier API.
• Step-by-step instructions to send and decrypt messages.
• Guide for generating and verifying ZK proofs.
• Instructions for extending the system for private community communications.

Extension Points:

Developers can easily:

• Add new encrypted message attributes or metadata fields.
• Implement multi-party private messaging.
• Integrate additional verification logic or proof types.
• Extend UI for DAOs, marketplaces, or decentralized organizations.

Community-First Impact Measurement:

We will track:

• Forks and stars to measure adoption.
• Issues and pull requests to track developer engagement.
• Derivative applications or extensions built on ZKMail.

Goal:

To provide a reference implementation for private, accountable, and Zero-Knowledge verified messaging, allowing developers and communities to safely onboard confidential workflows without exposing sensitive data.

[Your Project and Solution] Solution

Please describe your proposed solution and how it addresses the problem

Solution: Confidential Zero-Knowledge Messaging Framework for Midnight

ZKMail is a practical, end-to-end Proof-of-Concept demonstrating how confidential communication can be built on Midnight using Compact contracts and Zero-Knowledge proofs. While current Midnight examples illustrate isolated features, none provide a realistic, fully integrated workflow that developers or organizations can immediately understand and reuse. ZKMail fills this critical gap by delivering a small, focused, but technically complete messaging framework that showcases programmable privacy in action.

1. Private Messaging via ZK-Verified Compact Contracts

Most blockchains expose all data publicly. Midnight’s programmable privacy allows secure communication, but developers need a working blueprint to understand how to implement it.

ZKMail introduces:

• Encrypted message storage using off-chain encryption + on-chain commitments.
• Zero-Knowledge proof validation ensuring message authenticity without revealing content.
• Selective disclosure so only allowed recipients can decrypt messages.
• Optional ProfileNFT binding to anchor identity proofs without leaking private info.

These components demonstrate how privacy-preserving data can be shared, verified, and queried safely within Midnight’s Compact architecture.

2. Full Frontend Integration for Real-World Workflows

A PoC is only useful when people can see and use it.

ZKMail provides a clean, accessible UI that demonstrates:

• Composing messages.
• Sending encrypted data.
• Decrypting received messages.
• Verifying ZK proofs invisibly as part of the workflow.

Wallet signing and safe transaction flows.

This UI acts as a reference implementation for privacy-first DApps, DAOs, or confidential notification systems.

3. A Modular, Developer-Friendly Reference Implementation

Everything in ZKMail is intentionally structured for learning and reusability:

• Clear separation of contracts, encryption logic, UI, ZK proof scripts, and tests.
• Example scripts showing exactly how to: - Generate commitments - Produce proofs - Encrypt/decrypt payloads - Integrate with Glacier & Midnight APIs
• Documentation and diagrams explaining the privacy flows step-by-step.

This turns ZKMail from a simple demo into a reliable template for future teams building confidential workflows.

4. Practical Scope — Small but Complete

Instead of trying to build a big product, ZKMail focuses on delivering a fully functional, end-to-end slice of confidential messaging that includes:

• Message lifecycle
• ZK verification
• Identity anchoring
• Frontend usage
• Tests
• Documentation

This ensures the project can be completed quickly, tested thoroughly, and used immediately by the community.

5. Foundation for Future Midnight dApps

ZKMail is designed to be extended. Developers can use it as a base to build:

• DAO confidential voting/coordination
• Private proposal systems
• Secure organizational messages
• Private marketplace negotiations
• Compliance workflows with selective data disclosure

By providing a working, modular system, ZKMail accelerates innovation within the Midnight ecosystem.

[Your Project and Solution] Impact

Please define the positive impact your project will have on Midnight ecosystem

ZKMail will deliver practical and lasting benefits to the Midnight ecosystem by providing a reference implementation of confidential, ZK-enabled messaging. Key impacts include:

1. Faster learning curve for developers

• New developers on Midnight often struggle with understanding Compact contracts, off-chain encryption, and privacy workflows. ZKMail offers a fully working, forkable codebase, enabling them to see how everything integrates in practice and reducing the learning curve from weeks to hours.

2. Foundation for diverse privacy-focused dApps

• The modular architecture allows teams to adapt and extend ZKMail for messaging, private identity management, governance experiments, or other Catalyst PoCs, expanding the types of applications built on Midnight.

3. Hands-on examples of programmable privacy

• By including ZK proof generation, selective disclosure logic, and secure UI interactions, ZKMail provides concrete guidance on when and how to apply privacy patterns in real-world workflows. This helps developers understand and adopt privacy-first practices.

4. Encouraging clean, maintainable development

• With well-structured code, tests, documentation, and extension points, ZKMail sets a practical benchmark for quality, helping the ecosystem avoid fragmented or inconsistent practices in early-stage projects.

5. Sustainable community resource

• Released under MIT license, ZKMail can be reused, remixed, and referenced in tutorials, hackathons, or other projects. Over time, this creates a compounding effect: more forks, contributions, and examples that strengthen the Midnight ecosystem.

Indicators of impact:

• Number of forks, stars, and issues on GitHub.
• Adoption by developers in subsequent Catalyst proposals or community experiments.
• Feedback from developer surveys or informal community channels.
• References in tutorials, workshops, and learning materials.

ZKMail makes the Midnight ecosystem more accessible, educational, and extendable. It provides a reusable reference for privacy-preserving dApps, demonstrates best practices, and encourages experimentation with ZK-enabled workflows beyond financial use cases.

[Your Project and Solution] Capabilities & Feasibility

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?

Team Skills & Experience

Our team brings practical experience in blockchain engineering, privacy-focused development, and secure messaging workflows—skills that directly match the needs of building a Zero-Knowledge messaging PoC on Midnight.

• Blockchain & Smart Contracts: Hands-on work with Cardano integrations, Compact-style contract patterns, and decentralized application architecture.
• Zero-Knowledge & Cryptography: Familiarity with ZK proof flows, curve25519-based cryptography, and privacy-preserving data models.
• Messaging & Encryption: Prior implementation of encrypted messaging logic, off-chain pipelines, secure communication flows, and message-verification steps.
• Full-Stack Development: Strong proficiency in TypeScript, React/Next.js, Node.js, and integrating backend logic into clean, intuitive UIs.
• Efficient PoC Delivery: Proven ability to deliver compact, end-to-end prototypes with documentation and reproducible workflows.
• Lean, High-Coordination Team: A two-developer setup ensures fast iteration, minimal overhead, and tight technical alignment.
• These combined capabilities provide a complete skillset to deliver a reliable, technically solid, and reusable confidential-messaging PoC for the Midnight ecosystem.

Project Execution & Management

• The work is divided into clear, manageable phases with well-defined deliverables (contracts, integrations, tests, documentation, demo).
• Milestone-based progress tracking ensures predictable execution and transparent progress.
• Technical risks are mitigated early by relying exclusively on stable Midnight devnet components and proven cryptographic tooling.
• Project updates will be reflected consistently through GitHub commits, documentation progress, and milestone checkpoints.

Financial Transparency

• The budget is directly tied to development time and specific responsibilities (contract logic, encryption pipeline, frontend integration, testing).
• A small two-person team minimizes overhead and ensures cost-effective development.
• All code, commits, and artifacts are open source, providing natural auditability and traceability for all funded work.

Feasibility Validation

• All required tools—Midnight devnet, Glacier, Compact contract patterns, JS/TS cryptography libraries, and ZK reference circuits—are already available and pre-tested.
• The team has direct experience building encrypted messaging flows, cryptographic pipelines, and frontend–backend integrations, significantly reducing implementation risk.
• Reproducibility is built in: example scripts, a clean repo structure, and open-source documentation make the PoC straightforward for others to clone and run.
• A structured testing approach (unit tests, encryption/proof verification, and end-to-end UI flows) ensures stability and minimizes integration issues.
• Open-source publication enables community validation, improves trust, and increases long-term value for the Midnight ecosystem.

[Final Pitch] Budget & Costs

Please provide a cost breakdown of the proposed work and resources

Total Request: $8,890 USDM

This budget covers the development and delivery of a fully open-source ZKMail Proof-of-Concept, demonstrating confidential end-to-end messaging, Zero-Knowledge proofs, selective disclosure, and ProfileNFT integration on Midnight devnet. Costs are broken down as follows:

1. Lead Developer (Blockchain & Full-Stack) – $5,500 USDM (62%)

Responsibilities:

• Design the full system architecture, privacy model, and end-to-end workflow for ZKMail.
• Develop core smart contracts for confidential messaging, ZK proof generation, selective disclosure, and ProfileNFT creation.
• Build off-chain messaging workflows, encryption pipeline, and integration with frontend components.
• Ensure contracts compile, pass unit and integration tests, and produce reusable reference code.
• Contribute to documentation, example workflows, and developer onboarding materials.

Rationale:

• The Lead Developer role requires specialized knowledge in blockchain, smart contracts, and Zero-Knowledge proofs, as well as practical experience in privacy-preserving messaging systems. This budget reflects ~160 hours of focused, high-value development, covering both smart contract and PoC end-to-end integration, ensuring a high-quality, maintainable, and reusable codebase.

2. Full-Stack Developer – $3,390 USDM (38%)

Responsibilities:

• Develop a responsive React/Next.js frontend for the confidential messaging PoC (Inbox / Compose / Sent, dark mode support).
• Integrate with Lace wallet for transaction signing and devnet interaction.
• Implement real-time encrypted messaging workflow and enforce selective reveal logic in the UI.
• Update GitHub repository with code, integration modules, and frontend examples.
• Provide onboarding instructions, basic test examples, and frontend documentation for developers.

Rationale:

• The Full-Stack Developer ensures the PoC is functional, user-friendly, and demonstrates end-to-end encrypted messaging. This budget covers ~130 hours of work, focusing on practical implementation, integration with smart contracts, and usability for a reference/demo application.

3. Project budget details here:

https://docs.google.com/spreadsheets/d/1mHu2k6tZbZCjP6nNMiKqGlrh_dWHsRak1qfr2KhTxvQ/edit?gid=0#gid=0

[Final Pitch] Value for Money

How does the cost of the project represent value for the Midnight ecosystem?

This project delivers tangible and lasting value to the Midnight ecosystem by providing a fully functional, open-source reference application for confidential on-chain messaging powered by zero-knowledge proofs. Unlike conceptual demos or theoretical prototypes, ZKMail is a complete end-to-end solution that integrates:

• Smart contracts for secure message storage and selective disclosure.
• Zero-Knowledge (ZK) circuits that guarantee message confidentiality while enabling verifiable workflows.
• Frontend interface designed for real-world usability, allowing users to send, receive, and manage encrypted messages.
• Automated tests and thorough documentation under the MIT license, ensuring the system is easy to learn from, fork, and extend.

Key Benefits for Midnight and Developers

• Ready-to-use template for developers: ZKMail provides a practical starting point for developers interested in building privacy-preserving messaging applications. The reference implementation demonstrates how smart contracts, ZK proofs, and frontend integrations can work together seamlessly.
• Extending Midnight’s ecosystem: The project showcases programmable privacy applied to communication, extending Midnight’s value beyond financial applications and highlighting new potential use cases for decentralized messaging.
• Educational and practical resource: The PoC is designed not only as a prototype but also as a long-term learning tool for tutorials, hackathons, and internal experimentation. Developers can study the codebase, test the workflows, and adapt it for their own projects.
• High-quality and cost-efficient implementation: Developed by a single experienced developer, the project balances cost efficiency with code quality, producing a reusable, maintainable, and functional reference system without the overhead of a larger team.
• Encouraging adoption and experimentation: By providing an accessible, working example of privacy-preserving on-chain messaging, ZKMail accelerates developer adoption, inspires innovation, and serves as a reference point for integrating zero-knowledge proofs into real-world applications.

Investment Rationale

For an investment of $8,890 USDM, Midnight gains:

• A ready-to-use PoC demonstrating how confidential messaging can be implemented on-chain using ZK proofs.
• A showcase of programmable privacy, highlighting practical, privacy-first applications that extend the ecosystem.
• A reusable educational resource that can support learning, experimentation, and community engagement for years to come.
• High-quality, maintainable code delivered efficiently, ensuring the project is both practical and cost-effective.

In summary, this project combines practical engineering, careful attention to detail, and long-term educational value, making it a strategic investment for Midnight and a meaningful contribution to the ecosystem.

[Self-Assessment] Self-Assessment Checklist

I confirm that the proposal clearly provides a basic prototype reference application for one of the areas of interest.

Yes

I confirm that the proposal clearly defines which part of the developer journey it improves and how it makes building on Midnight easier and more productive.

Yes

I confirm that the proposal explicitly states the chosen permissive open-source license (e.g., MIT, Apache 2.0) and commits to a public code repository.

Yes

I confirm that the team provides evidence of their technical ability and experience in creating developer tools or high-quality technical content (e.g., GitHub, portfolio).

Yes

I confirm that a plan for creating and maintaining clear, comprehensive documentation is a core part of the proposal's scope.

Yes

I confirm that the budget and timeline (3 months) are realistic for delivering the proposed tool or resource.

Yes

[Required Acknowledgements] Consent & Confirmation

I Agree

Yes