Canonical Transport Layer for Private Notes

## TL;DR

**Goal:** Create a secure and user-friendly transport layer for off-chain private notes in the Miden ecosystem.
**Why it matters:** Miden users cannot consume private notes without receiving the note data directly — and no canonical, scalable solution for this exists yet.
**Opportunity:** We're looking for collaborators to help build a PoC and iterate toward a decentralized production system.

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## Problem: Private Note Data Is Off-Chain

Miden’s [private notes](https://0xmiden.github.io/miden-docs/imported/miden-base/src/note.html#note-storage-mode) are not stored on-chain. Instead, only a *commitment* to the note is recorded in the [Note DB](https://0xmiden.github.io/miden-docs/imported/miden-base/src/state.html#note-database). This preserves privacy but creates a challenge:
To consume a private note, an account must have access to the full note data. Since this data lives off-chain, consumers cannot fetch it from the blockchain — they must receive it directly, off-chain, from the note creator.

Miden supports exporting a note as a `.mno` file via the wallet or client. You can test this using the [faucet](https://faucet.testnet.miden.io/), then manually share the file with another client.
However, **there is no canonical, secure, and scalable way to transmit private notes between peers.**

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## Current Workaround

Today, developers share `.mno` files manually using Signal, Telegram, or email. This is fine for prototyping, but:

- It doesn’t scale to production apps
- It lacks privacy guarantees
- It creates friction and fragmentation

Each team could build their own solution — via WebRTC, decentralized storage, etc. — but that fragments the ecosystem and raises the barrier to entry.

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## Vision: Canonical Transport Layer

We want to provide a **canonical way to transmit private notes** between users.
This will be part of Miden’s core infrastructure and will support both the wallet and third-party applications.

We are looking for a development partner to help prototype and iterate toward a robust, decentralized implementation.

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## PoC Requirements

The goal of the proof-of-concept is to validate a minimal viable solution that can be integrated into early clients:

- **Confidentiality:** Note files must be encrypted. An operator may see “Alice sends something to Bob” but not the content.
- **Liveness:** Alice can send a note even if Bob is offline. Bob retrieves it once online.
- **Simple API:** Easy integration with wallet and clients (Rust and Web environments).
- **Existing tech:** If possible, use existing tech like IPFS or data sharing layers.

> The PoC can be centralized.

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## Final Product Direction

Long-term, we aim for a decentralized and privacy-preserving transport layer:

- All PoC features, plus:
- **Privacy:** Only Alice and Bob know that a transfer happened.
- **Group Sharing:** Alice can define a group of recipients (e.g. OTC trade counterparties).
- **Fees:** Find a convincing solution how to collect fees for your system.
- **Optional decentralization:** Use of DA layers (e.g., Avail, Celestia) or decentralized storage.

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## PoC Deliverables & Timeline

- A centralized prototype server enabling encrypted note transmission between two users
- Rust and Web APIs for:
- Sending a note (to a user ID or address)
- Fetching pending notes (for the recipient)
- Marking notes as received
- Basic CLI or Web UI for local testing
- Integration documentation

> **Timeline:** We aim to validate a working PoC within 4–6 weeks of kickoff.

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## Non-Goals (for PoC)

- No need for decentralized infrastructure (yet)
- No user authentication or wallet integration
- No content validation — only encrypted file transfer is in scope

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## How to Engage

- Comment on this discussion to express interest
- Or email dominik@miden.team with a brief note about your team and relevant experience
- We’ll schedule a short call to align on scope and next steps

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## What We're Looking For

- Strong experience in Rust or secure backend systems
- Familiarity with cryptographic APIs and secure file handling
- Clear communication and ability to iterate quickly

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## Related Resources

- [Private Notes](https://0xmiden.github.io/miden-docs/imported/miden-base/src/note.html#note-structure)
- [Note Database](https://0xmiden.github.io/miden-docs/imported/miden-base/src/state.html#note-database)
- [Testnet Faucet](https://faucet.testnet.miden.io/)

_Originally posted by @Dominik1999 in https://github.com/0xMiden/miden-base/discussions/1388_