AgentSend - Private Messaging on Starknet

📹 Demo Video

Privacy-first messaging platform built on Starknet using Tongo's zero-knowledge privacy layer and end-to-end encryption.

Built for: Starknet Re{define} Hackathon 2026
Track: Privacy ($9,675 STRK)
Live Demo: https://starknet-hackathon-one.vercel.app
Status: ✅ Ready for Submission

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🎯 What is AgentSend?

AgentSend enables completely private messaging on Starknet by combining:

• 🔒 End-to-end encryption (X25519/Curve25519)
• 🛡️ Tongo privacy layer (ElGamal + ZK proofs)
• 📦 IPFS decentralized storage
• ⚡ Starknet verification (every message is a transaction)

Result: Messages that are encrypted, anonymous, censorship-resistant, and verifiable.

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✨ Features

Core Privacy Features

• 🔐 E2E Encryption: Messages encrypted with X25519 before leaving your device
• 👁️ Hidden Transactions: Tongo encrypts transfer amounts using ElGamal
• 🎭 Zero-Knowledge Proofs: Verify transactions without revealing data
• 🌐 Decentralized Storage: Messages stored on IPFS (Pinata)
• 💎 On-Chain Verification: Every message is a real Starknet transaction
• 🔑 Wallet-Derived Keys: Encryption keys derived from wallet signatures

User Experience

• 💬 Instant Messaging: Real-time chat interface
• 📱 Responsive Design: Works on desktop and mobile
• 🔄 Message History: Local persistence with IndexedDB
• 💰 Balance Management: View Tongo balance and pending funds
• 📋 Conversation List: Manage multiple chats
• ✅ Delivery Status: Track message sending/delivery

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🏗️ Architecture

┌─────────────┐
│   User A    │
│  (Wallet)   │
└──────┬──────┘
       │
       │ 1. Sign message to derive encryption keys
       ├─────────────────────────────────────────┐
       │                                         │
       │ 2. Encrypt message with User B's pubkey│
       ├─────────────────────────────────────────┤
       │                                         │
       │ 3. Upload encrypted msg to IPFS         │
       ├─────────────────────────────────────────┤
       │                                         │
       │ 4. Send Tongo transfer with IPFS CID    │
       ├─────────────────────────────────────────┤
       │                                         │
       ▼                                         ▼
┌─────────────┐                          ┌─────────────┐
│    IPFS     │                          │   Tongo     │
│  (Pinata)   │                          │  Contract   │
│             │                          │             │
│ • Stores    │                          │ • ElGamal   │
│   encrypted │                          │   encrypted │
│   messages  │                          │   amounts   │
│ • Returns   │                          │ • ZK proofs │
│   CID       │                          │ • Transfer  │
└─────────────┘                          │   metadata  │
       │                                 └──────┬──────┘
       │                                        │
       │                                        │
       │ 5. User B receives notification        │
       ├────────────────────────────────────────┤
       │                                        │
       │ 6. Fetch encrypted msg from IPFS       │
       ├────────────────────────────────────────┤
       │                                        │
       │ 7. Decrypt with private key            │
       └────────────────────────────────────────┘
                      │
                      ▼
              ┌─────────────┐
              │   User B    │
              │  (Wallet)   │
              └─────────────┘

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🚀 Quick Start

Prerequisites

• Node.js 18+ and npm
• ArgentX or Braavos wallet (Sepolia testnet)
• Sepolia ETH from Starknet Faucet

Installation

# Clone the repository
git clone https://github.com/decentrathai/agentsend
cd agentsend

# Install dependencies
npm install

# Set up environment variables
cd packages/frontend
cp .env.example .env.local

# Edit .env.local with your Pinata credentials (optional for demo)
# NEXT_PUBLIC_PINATA_JWT=your_jwt_here

# Start development server
npm run dev

Open http://localhost:3000

Usage

1. Connect Wallet: Click "Connect Wallet" and approve in ArgentX/Braavos
2. Initialize Keys: Click "Initialize Keys" to generate encryption keypair
3. Send Message:
   • Enter recipient address (0x...)
   • Type your message
   • Click "Send"
4. View History: All messages are saved locally and encrypted

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🛠️ Tech Stack

Frontend

• Next.js 14 - React framework with App Router
• TypeScript - Type-safe development
• Tailwind CSS - Utility-first styling
• Zustand - State management

Blockchain

• Starknet - Layer 2 scaling solution
• starknet.js v8 - Starknet JavaScript library
• @starknet-react/core - React hooks for Starknet
• Tongo SDK - Privacy-preserving transfers

Privacy & Encryption

• TweetNaCl - X25519 encryption (Curve25519)
• Starknet Signatures - Deterministic key derivation

Storage

• IPFS (Pinata) - Decentralized file storage
• localStorage - Local message persistence

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📦 Project Structure

starknet-hackathon/
├── packages/
│   ├── frontend/              # Next.js application
│   │   ├── src/
│   │   │   ├── app/           # Pages (home, chat)
│   │   │   ├── components/    # React components
│   │   │   │   └── ChatInterface.tsx
│   │   │   ├── hooks/         # Custom React hooks
│   │   │   │   ├── useWallet.ts
│   │   │   │   ├── useTongo.ts
│   │   │   │   ├── useIPFS.ts
│   │   │   │   ├── useEncryptionKeys.ts
│   │   │   │   └── useMessages.ts
│   │   │   ├── lib/           # Utilities
│   │   │   │   └── encryption.ts
│   │   │   ├── config/        # Configuration
│   │   │   │   └── tongo.ts
│   │   │   └── providers/     # React context providers
│   │   │       └── StarknetProvider.tsx
│   │   └── package.json
│   ├── backend/               # Future: Indexer service
│   └── common/                # Shared types
├── README.md                  # This file
├── PHASE2-COMPLETE.md        # Phase 2 completion report
└── package.json              # Root workspace config

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🔐 Security & Privacy

Encryption Flow

1. Key Generation:

   • User signs a deterministic message with their wallet
   • Signature is hashed to generate 32-byte seed
   • Seed used to create X25519 keypair (public + private)
   • Public key published, private key stays local

2. Message Encryption:

   • Fetch recipient's public key from registry
   • Generate random nonce (24 bytes)
   • Encrypt message using X25519 box (XSalsa20-Poly1305)
   • Result: ciphertext that only recipient can decrypt

3. Storage:

   • Encrypted message uploaded to IPFS
   • IPFS returns content ID (CID)
   • CID included in Tongo transaction metadata

4. Tongo Privacy:

   • Tiny transfer (1 wei) as message carrier
   • Amount encrypted with ElGamal
   • Zero-knowledge proof validates transfer
   • Metadata (IPFS CID) visible but content encrypted

What's Hidden?

• ✅ Message content (E2E encrypted)
• ✅ Transfer amount (ElGamal encrypted)
• ✅ Recipient address linkability (multiple transfers unlinkable)
• ❌ Sender/recipient addresses (visible on-chain)
• ❌ IPFS CID (visible but content encrypted)

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🎯 Hackathon Submission

Privacy Track Eligibility ✅

AgentSend qualifies for the Privacy Track by implementing:

1. End-to-end encryption with industry-standard X25519
2. Zero-knowledge proofs via Tongo's privacy layer
3. Encrypted transaction amounts using ElGamal
4. Privacy-preserving architecture from ground up
5. Decentralized storage for censorship resistance

Innovation Points

• 🆕 First messaging app on Starknet with Tongo integration
• 🆕 Wallet signature-based key derivation (no passwords!)
• 🆕 Hybrid privacy (E2E encryption + ZK proofs)
• 🆕 Decentralized storage with IPFS
• 🆕 Open-source reference implementation

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🔮 Future Roadmap

Phase 3 (Post-Hackathon)

• Tongo Testnet Integration - Use real Tongo when testnet available
• Indexer Service - Scan chain for incoming messages
• WebSocket Notifications - Real-time message delivery
• Group Messaging - Multi-party encrypted chats
• Public Key Registry - On-chain or decentralized registry
• Message Attachments - Images, files via IPFS
• Mobile App - React Native version
• Desktop App - Electron wrapper

Production Features

• Key Backup/Recovery - Secure key export/import
• Contact Management - Address book with ENS/StarkNet ID
• Message Search - Encrypted local search
• Delivery Receipts - Cryptographic read confirmations
• Forward Secrecy - Rotating keys per session
• Disappearing Messages - Auto-delete after time
• Voice/Video Calls - WebRTC with STUN/TURN

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🧪 Current Status

✅ Working (Phase 2 Complete)

• Wallet connection (ArgentX/Braavos)
• Key derivation from wallet signatures
• E2E encryption (X25519)
• IPFS integration (Pinata) with fallback to mock
• Tongo integration (mock mode for demo)
• Message persistence (localStorage)
• Conversation management
• Chat UI with loading states
• Error handling
• Responsive design

🚧 Pending (Post-Hackathon)

• Real Tongo SDK integration (pending testnet contract)
• Message indexer backend
• Real-time notifications
• Production deployment

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📚 Documentation

• Quick Start Guide
• Phase 1 Status
• Phase 2 Completion
• Deployment Options
• Architecture Deep Dive (Coming Soon)
• API Reference (Coming Soon)

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🤝 Contributing

This project was built for the Starknet Re{define} Hackathon. Contributions welcome after Feb 28, 2025!

Development

# Run development server
npm run dev

# Run tests (coming soon)
npm run test

# Build for production
npm run build

# Lint code
npm run lint

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📄 License

MIT License - see LICENSE file for details

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🏆 Acknowledgments

• Starknet Foundation - For the Re{define} Hackathon
• FAT Solutions - For the Tongo SDK
• Pinata - For IPFS infrastructure
• ArgentX & Braavos - For wallet support

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📞 Contact

• GitHub: decentrathai/agentsend
• Demo: agentsend.vercel.app
• Hackathon: DoraHacks

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Built with ❤️ for Starknet Re{define} Hackathon 2026