Mist Protocol

Status: EC2 instance terminated.

First Mover Sprint Submission

Privacy-preserving DeFi swaps on Sui using TEE (Trusted Execution Environment) and SEAL encryption

Built with: AWS Nitro Enclaves • SEAL • Sui

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What is Mist Protocol?

Mist Protocol enables truly private token swaps on Sui by combining:

• SEAL threshold encryption for hiding swap amounts
• TEE (AWS Nitro Enclaves) for trusted execution with hardware attestation
• Privacy relayer to break on-chain linkability
• Stealth addresses for unlinkable swap outputs

Unlike traditional DEXs where every swap is publicly visible, Mist Protocol keeps swap amounts private while maintaining verifiability through TEE attestation.

---

Key Innovation

Privacy Through Stealth Addresses

Traditional DEX:                  Mist Protocol:
User Wallet → Swap → Output       User → Deposit → Intent → TEE → Stealth → Claim
     ↑                                     ↑                        ↑
  Publicly linked              No owner field              Unlinkable address

Result: On-chain observers cannot link deposits to swap outputs!

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How It Works

1. Deposit & Get Deposit Note

User deposits 1.0 SUI
  ↓
Creates deposit with secret nullifier
  ↓
Deposit note stored locally (encrypted)
On-chain: Deposit object (no owner field - privacy!)

2. Create Swap Intent

User generates stealth addresses (output + remainder)
  ↓
Signs intent with wallet (proves ownership)
  ↓
Frontend SEAL-encrypts: nullifier, amounts, stealth addresses
  ↓
Submit on-chain (direct or via optional relayer)
  ↓
On-chain: SwapIntent added to IntentQueue

3. TEE Executes Swap

Backend polls queue every 5 seconds
  ↓
Decrypts with SEAL (2-of-3 threshold)
  ↓
Verifies wallet signature (prevents nullifier theft)
  ↓
TEE wallet executes swap on FlowX
  ↓
Sends output to stealth address (unlinkable!)

4. Claim from Stealth Address

User sees tokens at stealth address
  ↓
Claims to main wallet (sponsored tx)
  ↓
On-chain: No link between deposit and output!

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Architecture

┌──────────────┐
│   Frontend   │  Next.js + @mysten/dapp-kit + SEAL SDK
└──────┬───────┘
       │ Creates encrypted intents
       ▼
┌─────────────────────────────────────────────────────┐
│          Sui Blockchain (Move Contracts)            │
│                                                     │
│  Deposits       │  NullifierReg │  IntentQueue      │
│  (Shared)       │  (Shared)     │  (Shared)         │
│                                                     │
│  - No owner     │  - Spent      │  - Pending        │
│    field!       │    nullifiers │    intents        │
└─────────────────────────────────────────────────────┘
       ▲                                      │
       │                                      │ Polls every 5s
       │ Executes signed tx                  ▼
       │                          ┌──────────────────────┐
       │                          │  TEE Backend         │
       │                          │  (Rust + AWS Nitro)  │
       │                          │                      │
       │                          │  - SEAL decrypt      │
       │                          │  - DEX swap          │
       │                          │  - SEAL encrypt      │
       │                          │  - Build tx          │
       │                          └──────────┬───────────┘
       │                                     │
       │                                     │ POST /sign
       │                                     ▼
       │                          ┌──────────────────────┐
       └──────────────────────────│    tx-signer        │
                                  │  (HTTP Service)      │
                                  │                      │
                                  │  Wraps:              │
                                  │  sui keytool sign    │
                                  └──────────────────────┘

---

Tech Stack

Component	Technology
Smart Contracts	Sui Move
Backend (TEE)	Rust, Axum, SEAL SDK
Signing Service	Rust, Axum, Sui CLI
Frontend	Next.js 14, TypeScript, @mysten/dapp-kit
Encryption	SEAL (2-of-3 threshold encryption)
DEX	FlowX (testnet) → MIST_TOKEN
TEE	AWS Nitro Enclaves (hardware attestation)

---

Repository Structure

mist-protocol/
├── backend/              # TEE backend (Rust + AWS Nitro)
│   └── src/apps/mist-protocol/
│       ├── intent_processor.rs   # Polls IntentQueue
│       ├── swap_executor.rs      # Executes swaps via FlowX
│       └── seal_encryption.rs    # SEAL crypto
│
├── enclave/              # AWS Nitro Enclave deployment
│   ├── Makefile          # Build enclave image
│   ├── deploy.sh         # Deployment scripts
│   └── AWS_QUICKSTART.md # Deployment guide
│
├── tx-signer/            # Transaction signing service
│   └── src/main.rs       # HTTP wrapper around sui keytool
│
├── contracts/            # Sui Move smart contracts
│   └── mist_protocol/
│       └── sources/
│           ├── mist_protocol.move    # Main protocol
│           └── seal_policy.move      # TEE + user decryption
│
├── frontend/             # Next.js frontend
│   ├── app/              # Pages + privacy relayer API
│   ├── components/       # React components
│   └── lib/deposit-notes.ts # Stealth address + note management
│
└── docs/                 # Documentation

---

Quick Start

Prerequisites

sui --version    # 1.60.0+
node --version   # v20.0.0+
pnpm --version   # 8.0.0+
cargo --version  # 1.70.0+

1. Install Dependencies

# Frontend
cd frontend && pnpm install

# Backend (will download and build dependencies)
cd ../backend && cargo build --release

# Signing service
cd ../tx-signer && cargo build --release

2. Deploy Contracts

cd contracts/mist_protocol
sui client publish --gas-budget 500000000

# Save package_id, pool_id, queue_id from output

3. Configure

Backend: Update backend/src/apps/mist-protocol/seal_config.yaml Frontend: Update frontend/.env.local Backend key: Set in backend/.env

See docs/SETUP.md for detailed configuration.

4. Run

# Terminal 1: Signing service
cd tx-signer && cargo run

# Terminal 2: Backend
cd backend && cargo run

# Terminal 3: Frontend
cd frontend && pnpm dev

# Open http://localhost:3000

---

Live Demo Flow

1. Deposit SUI

• Connect wallet
• Deposit 0.5 SUI
• Receive deposit note with secret nullifier

2. Create Swap Intent

• Select deposit note (0.5 SUI)
• Swap to: MIST_TOKEN
• Sign intent with wallet
• Generates stealth addresses automatically

3. TEE Processes (Automatic)

Backend logs show:

📊 Poll cycle #5
✅ Successfully decrypted intent
   🎯 Intent: 0x1e6f...
   💱 Swap: 0.5 SUI → MIST_TOKEN
   ✅ Signature verified!

🔄 Executing swap on FlowX...
   🔐 Calling signing service...
   ✅ Transaction signed successfully!
   🚀 Executing signed transaction on-chain...
   ✅ Swap executed successfully!
   📝 Transaction: rkZeR5Fw5j...

4. Claim Output

• Check "Claim" tab
• See MIST_TOKEN at stealth address
• Click "Claim to Main Wallet"
• Tokens transferred (unlinkable on-chain!)

---

What Makes This Special

🔐 True Privacy

• Swap amounts encrypted with SEAL threshold encryption
• On-chain observers see only encrypted bytes
• Even node operators cannot see amounts

🔒 TEE Security

• AWS Nitro Enclaves provide hardware-based trusted execution
• Cryptographic attestation proves code integrity
• SEAL keys released only to verified TEE
• Ephemeral keypairs generated inside enclave (never written to disk)

🎯 Intent-Based

• Users submit intents, TEE executes asynchronously
• No need to stay online during swap
• MEV-resistant (intents processed in queue order)

🔄 Privacy Relayer (Optional)

• Relayer can submit swap intents on behalf of users
• User's wallet never touches the swap transaction
• Extra privacy layer for those who want it

💡 Stealth Addresses

• Swap outputs sent to unlinkable stealth addresses
• User generates keypair locally, only they can claim
• On-chain: No link between deposit and output

---

Current Status

✅ Working Features (Tested & Verified)

• Deposit tokens with secret nullifier
• Create encrypted swap intents with stealth addresses
• Optional privacy relayer (submits intents on behalf of users)
• Wallet signature verification (prevents nullifier theft)
• TEE polls IntentQueue every 5 seconds
• SEAL threshold decryption (2-of-3 key servers)
• Transaction signing via tx-signer service
• Execute swap on FlowX DEX
• Send output to unlinkable stealth addresses
• Claim tokens from stealth addresses

🚧 In Progress

• Cetus mainnet integration (implemented, pending deployment)
• Production deployment to AWS Nitro Enclaves (c5.xlarge)

Note: Testnet uses FlowX → MIST_TOKEN. Cetus mainnet swap is implemented but not yet deployed.

🎯 Future Enhancements

• Batch swap execution (multiple intents in one tx)
• Cross-pool swaps
• Additional token support
• Zero-knowledge proofs for enhanced privacy

---

Documentation

• Architecture - Complete system design and data flow
• Setup Guide - Installation, configuration, and deployment

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Technical Highlights

Transaction Signing Solution

Due to fastcrypto version conflicts between SEAL SDK and sui-types, we built a novel signing architecture:

• Backend: Handles all SEAL encryption (fastcrypto v1)
• tx-signer: Signs transactions only (fastcrypto v2)
• Result: Clean separation, no version conflicts

This HTTP wrapper pattern is production-ready and commonly used in Sui projects. See tx-signer/README.md.

SEAL Integration

First DeFi protocol on Sui to use SEAL threshold encryption for:

• User balance privacy
• TEE-verifiable decryption
• Dual-party access (user + TEE)

Wallet Signature Verification

Every swap intent requires a wallet signature to prevent nullifier theft attacks:

• Message format: mist_intent_v2:{nullifier}:{inputAmount}:{outputStealth}:{remainderStealth}
• TEE verifies signature before executing (Ed25519, Secp256k1, Secp256r1 supported)
• Attackers cannot steal nullifiers without the user's wallet private key

Intent Queue Architecture

100% on-chain intent tracking:

• No database required
• Survives backend restarts
• Transparent and auditable
• Efficient RPC queries

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Security

Privacy Model

What's Private:

• Individual swap amounts (SEAL encrypted)
• Deposit ownership (no owner field on-chain)
• User → swap linkage (stealth addresses break link)

What's Public:

• Deposit events (no amounts, no owner)
• Intent queue state (encrypted contents)
• Stealth address balances (unlinkable to user)

Trust Model

Trusted:

• AWS Nitro Enclaves (hardware attestation via NSM API)
• SEAL key servers (2-of-3 threshold - no single point of failure)
• Smart contract logic (auditable on-chain)
• TEE backend address (hardcoded in contract for authorization)

Not Trusted:

• Individual key servers (threshold prevents collusion)
• RPC nodes (cannot decrypt - see only encrypted bytes)
• Frontend (encryption happens client-side with SEAL SDK)

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Demo

Testnet Deployment:

• Contracts: 0x584b4dd0e047e8cca64f82f5945a0f75cfd1c1e06d3757831a82369de976f89a
• Network: Sui Testnet

Try it yourself:

1. Get testnet SUI from faucet
2. Follow setup guide: docs/SETUP.md
3. Create a swap and watch the TEE process it!

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Resources

• Sui Documentation: https://docs.sui.io
• AWS Nitro Enclaves: https://aws.amazon.com/ec2/nitro/nitro-enclaves/
• SEAL Encryption: https://docs.mystenlabs.com/seal
• FlowX DEX: https://flowx.finance

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License

Apache-2.0

Mist Protocol built by Misty Labs

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Acknowledgments

• Mysten Labs for SEAL and Sui
• Cetus Protocol for DEX infrastructure
• AWS for Nitro Enclaves

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