dart_web3_mpc

A Multi-Party Computation (MPC) extension for the Dart Web3 ecosystem. Enable "keyless" security by distributing key shares across multiple devices or stakeholders using threshold cryptography.

🚀 Features

• TSS Support: Support for Threshold Signature Schemes (GG20 / GG18) in Dart.
• Shamir shares: Standard Shamir Secret Sharing (SSS) for backup and recovery.
• Distributed Signing: Create valid ECDSA signatures without ever assembling a full private key on one device.
• Enterprise Ready: Designed for institutional wallet flows and 2-of-2 mobile-cloud pairings.

Usage Flow

sequenceDiagram
    participant A as Client Share
    participant B as Server Share
    participant C as MPC Orchestrator
    A->>C: sign_intent(hash)
    C->>B: request_partial_sig
    B-->>C: partial_proof_b
    C->>A: request_partial_sig
    A-->>C: partial_proof_a
    C->>C: aggregate_signatures
    C-->>A: Final Valid Signature

🏗️ Architecture

graph TD
    User[Signer A] --> Comm[P2P Channel]
    Cloud[Server B] --> Comm
    
    subgraph Wallet [Distributed Identity]
        ShareA[Key Share A]
        ShareB[Key Share B]
    end
    
    Comm --> Combine[Partial Sig Math]
    Combine --> Target[Valid Ethereum Sig]

📚 Technical Reference

Core Classes

🛡️ Security Considerations

• Secure Channels: MPC communication must happen over TLS or E2EE (End-to-End Encrypted) channels.
• Share Persistence: Never store MPC shares in plain text. Use dart_web3_dapp secure store hooks or platform-native keychain.
• Node Reputation: In n-of-m setups, ensure the participant nodes are decentralized and not controlled by a single entity.

💻 Usage

2-of-2 Distributed Signing (Concept)

import 'package:dart_web3_mpc/dart_web3_mpc.dart';

void main() async {
  final mpc = MpcSigner(localShare: myShare);

  // Initialize a signing round with a remote peer
  final round1 = await mpc.startSigningRound(transactionData);
  
  // Exchange data with Server B...
  final finalSig = await mpc.finalize(round2Data);
  print('Final MPC Signature: ${finalSig.toHex()}');
}

📦 Installation

dependencies:
  dart_web3_mpc: ^0.1.0