A web application for creating and managing co-signed contracts using the Nostr protocol.

Cosigner is a prototype implementation of a co-signed contracts system built on Nostr, specifically using kind: 30023 events. It allows users to:

• Upload markdown documents as contracts
• Specify required signatories using Nostr public keys
• Sign contracts using their Nostr keys
• Track the status of contracts
• Resolve signature conflicts

• Authentication: Sign in with NIP-07 browser extensions or directly with nsec keys
• Contract Management: Upload, view, and sign contracts
• Markdown Support: Contracts are written in markdown format
• Signature Verification: Cryptographic verification of signatures
• Conflict Resolution: Handling of signature conflicts due to Nostr's immutable nature

• Built with React and TypeScript
• Uses nostr-tools for Nostr protocol integration
• Implements the sequential signing approach (1a) as described in the specification
• Connects to relay.primal.net for Nostr event publishing and subscription

• Node.js (v16 or later)
• npm or yarn

1. Clone the repository:

   git clone https://github.com/djinoz/cosigner.git
   cd cosigner
   

2. Install dependencies:

   npm install
   

3. Start the development server:

   npm run dev
   

4. Open your browser and navigate to http://localhost:5173

• Use a NIP-07 compatible browser extension (like Alby or nos2x)
• Or sign in with your nsec key (not recommended for production use)
• For testing, you can generate a new key pair

1. Click "Upload Contract" in the navigation bar
2. Upload a markdown file or paste markdown content
3. Enter a title for the contract
4. Add the Nostr public keys (npub) of all required signatories
5. Specify the minimum number of signatures required
6. Click "Publish Contract"

1. Navigate to the Contracts list
2. Find a contract that needs your signature
3. Click "View" to see the contract details
4. Review the contract content
5. Click "Sign Contract" to add your signature

If multiple signatories sign simultaneously, conflicts may occur. In this case:

1. The contract will show a warning about multiple versions
2. Click "Resolve Conflicts" to merge the signatures
3. Once resolved, the contract can be signed by remaining signatories

• This is a prototype implementation and not intended for production use
• All cryptographic operations are performed client-side
• Private keys (nsec) are never stored or transmitted, only kept in memory during the session
• The application includes a simulation mode that allows it to function without requiring an actual Nostr relay connection
• For real-world usage, the application would connect to a Nostr relay (configured to use relay.primal.net)

~~ - Simulation Mode: The application can operate in a simulation mode where it generates sample contracts and simulates signing operations, allowing you to test the full workflow without a real Nostr relay ~~ ~~ - Fallback Mechanisms: If a contract is not found in the relay, the application will generate a simulated contract for demonstration purposes~~

• Authentication Flexibility: Supports both NIP-07 browser extensions and direct nsec key input, with fallback mechanisms to ensure signing always works
• Error Handling: Comprehensive error handling throughout the application to provide a smooth user experience

MIT