dart_web3_signer #

A universal signing abstraction for the Dart Web3 ecosystem. It decouples identity management from execution logic, supporting local, hardware, and remote signing workflows.

🚀 Features #

• Unified Signer Protocol: One interface for all signing methods (EOA, MPC, HW).
• EIP-712 Support: Domain-separated, typed data signing for human-readable approvals.
• Hardware Integration: High-level hooks for Ledger, Trezor, and Keystone devices.
• Message Standards: Built-in support for personal_sign and Ethereum-prefixed message hashing.

Usage Flow #

sequenceDiagram
    participant U as User
    participant C as Controller
    participant S as Signer (Keys)
    participant E as ECDSA
    U->>C: signMessage("hello")
    C->>S: request permission
    S->>S: hash(prefix + "hello")
    S->>E: sign(hash, privateKey)
    E-->>S: signature (r,s,v)
    S-->>U: hex string

🏗️ Architecture #

graph LR
    User[User Intent] --> Controller[Signer Controller]
    
    subgraph Implementations [Identity Sources]
        PK[PrivateKeySigner]
        HW[HardwareSigner]
        AA[SmartAccountSigner]
    end
    
    Controller --> Implementations
    Implementations --> Sig[EthSignature]

📚 Technical Reference #

Core Classes #

🛡️ Security Considerations #

• Key Isolation: Keep PrivateKeySigner instances confined to the narrowest possible scope. Never share them across thread boundaries if possible.
• Approval Verification: When using signTypedData, always display the parsed JSON in the UI for the user to verify before calling the signer.
• Hardware Timeouts: Implement proper timeout handling when interacting with hardware signers (Level 6) to avoid app freezes.

💻 Usage #

Signing EIP-712 Typed Data #

import 'package:dart_web3_signer/dart_web3_signer.dart';

void main() async {
  final signer = PrivateKeySigner.fromHex('0x...', 1);
  
  final data = TypedData(
    domain: TypedDataDomain(name: 'MyDapp', version: '1'),
    types: {...},
    primaryType: 'Mail',
    message: {'contents': 'Hello!'},
  );

  final signature = await signer.signTypedData(data);
  print('Signature: ${signature.toHex()}');
}

📦 Installation #

dependencies:
  dart_web3_signer: ^0.1.0