expo-trust-core

v1.0.9

Published

5 days ago

Production-ready multi-blockchain wallet SDK for React Native and Expo. Built on Trust Wallet Core with native transaction signing (Ethereum, Solana, Bitcoin), EIP-712 support, and comprehensive blockchain helpers.

expo-trust-core

Multi-blockchain wallet SDK for React Native and Expo applications.

Built on Trust Wallet Core with comprehensive blockchain integration helpers.

Features

Core Cryptography

✅ BIP39 Mnemonic generation (12/24 word phrases)
✅ HD Wallet support (BIP44/BIP84)
✅ Multi-chain address generation
✅ Message signing (EIP-191, Ed25519)
✅ EIP-712 Typed Data signing (production-grade)
✅ Multiple accounts per mnemonic (0-∞)

Advanced Features

✅ Private key export and import
✅ Public key export
✅ Single-key wallet mode

Native Transaction Signing (v1.0+)

✅ Full Protobuf signing on iOS & Android
✅ Ethereum (Legacy + EIP-1559)
✅ Solana (SOL transfers)
✅ Bitcoin (SegWit UTXO-based)
✅ signRawTransaction() for advanced flows
✅ Private keys NEVER exposed to JavaScript

Blockchain Integration Helpers

EVM Chains (Ethereum, Polygon, Arbitrum, BSC, Base, Optimism, Avalanche)

Balance checking
ERC20 token support
Transaction builder with gas estimation
EIP-1559 support
Full transaction signing

Solana

SOL balance checking
SPL token support
Transaction builder
Full transaction signing (including Jupiter/Raydium swap support)

Bitcoin

Balance checking via multiple APIs
UTXO management
Transaction builder with fee calculation
SegWit support

Dogecoin

Balance checking
UTXO management
Transaction builder

Installation

1. Install SDK

npm install expo-trust-core

yarn add expo-trust-core

2. Install Required Dependencies

The SDK requires these peer dependencies:

npm install ethers@^6.13.0 @solana/web3.js@^1.95.0

3. Install Solana Polyfills (Required)

For Solana support, install these polyfills:

npm install react-native-get-random-values fast-text-encoding buffer

4. Configure Polyfills

Add to your app entry point (App.tsx or app/_layout.tsx) before any other imports:

import 'react-native-get-random-values';
import 'fast-text-encoding';
import { Buffer } from 'buffer';
global.Buffer = Buffer;

// Now your other imports
import { App } from './App';

Why polyfills? The @solana/web3.js library requires Node.js crypto APIs (crypto.getRandomValues, TextEncoder) that are not available in React Native by default.

5. Platform-Specific Setup

iOS: No additional setup required.

Android: No additional setup required.

Complete Dependency List

{
  "dependencies": {
    "expo-trust-core": "^0.4.0",
    "ethers": "^6.13.0",
    "@solana/web3.js": "^1.95.0",
    "react-native-get-random-values": "^1.11.0",
    "fast-text-encoding": "^1.0.6",
    "buffer": "^6.0.3"
  }
}

---

## Quick Start

### Generate Wallet

```typescript
import { Mnemonic, HDWallet } from 'expo-trust-core';

// Generate 12-word mnemonic
const mnemonic = await Mnemonic.generate(128); // 128 bits = 12 words

// Create HD wallet
const wallet = new HDWallet(mnemonic);

Generate Addresses

import { Address, CoinType } from 'expo-trust-core';

// Bitcoin address (account 0)
const btcAddress = await Address.generate(mnemonic, CoinType.Bitcoin, 0);

// Ethereum address (works for all EVM chains)
const ethAddress = await Address.generate(mnemonic, CoinType.Ethereum, 0);

// Solana address
const solAddress = await Address.generate(mnemonic, CoinType.Solana, 0);

// Dogecoin address
const dogeAddress = await Address.generate(mnemonic, CoinType.Dogecoin, 0);

// Multiple accounts from same mnemonic
const ethAccount1 = await Address.generate(mnemonic, CoinType.Ethereum, 1);
const ethAccount2 = await Address.generate(mnemonic, CoinType.Ethereum, 2);

Sign Messages

import { Message, CoinType } from 'expo-trust-core';

// Ethereum Personal Sign (EIP-191)
const signature = await Message.signEthereumMessage(
  mnemonic,
  'Sign in to OpenSea',
  0 // account index
);

// Solana Message Sign
const solSignature = await Message.signSolanaMessage(
  mnemonic,
  'Sign in to Magic Eden',
  0
);

Sign Typed Data (EIP-712)

import { TypedData, CoinType } from 'expo-trust-core';

const typedData = {
  domain: {
    name: 'MyDApp',
    version: '1',
    chainId: 1,
    verifyingContract: '0x...',
  },
  types: {
    Person: [
      { name: 'name', type: 'string' },
      { name: 'wallet', type: 'address' },
    ],
  },
  primaryType: 'Person',
  message: {
    name: 'Alice',
    wallet: '0x...',
  },
};

const signature = await TypedData.sign(mnemonic, typedData, CoinType.Ethereum, 0);

Blockchain Integration

Check EVM Balance

import { BalanceChecker } from 'expo-trust-core';

const myRpcUrl = 'https://eth-mainnet.g.alchemy.com/v2/YOUR_KEY';
const result = await BalanceChecker.checkEVM(address, myRpcUrl, 18);
console.log(`Balance: ${result.balance} ETH`);

// Works with ANY EVM chain
const maticBalance = await BalanceChecker.checkEVM(
  address,
  'https://polygon-rpc.com',
  18
);

Check ERC20 Token Balance

import { TokenChecker } from 'expo-trust-core';

const usdcAddress = '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48';
const token = await TokenChecker.checkERC20(
  walletAddress,
  usdcAddress,
  myRpcUrl
);
console.log(`${token.balance} ${token.symbol}`);

Build EVM Transaction

import { TransactionBuilder } from 'expo-trust-core';

const unsignedTx = await TransactionBuilder.buildEVMTransaction(
  fromAddress,
  toAddress,
  '0.5', // 0.5 ETH
  myRpcUrl
);

// Now sign with your wallet
// Then broadcast using ethers.js or web3.js

Check Solana Balance

import { SolanaBalanceChecker } from 'expo-trust-core';

const solanaRpc = 'https://api.mainnet-beta.solana.com';
const balance = await SolanaBalanceChecker.checkSOL(address, solanaRpc);
console.log(`Balance: ${balance.balance} SOL`);

Check SPL Token Balance

import { SolanaSPLChecker } from 'expo-trust-core';

const usdcMint = 'EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v';
const token = await SolanaSPLChecker.checkSPL(
  walletAddress,
  usdcMint,
  solanaRpc
);
console.log(`${token.balance} USDC`);

Bitcoin Support

import { BitcoinBalanceChecker, BitcoinTransactionBuilder } from 'expo-trust-core';

// Check balance
const balance = await BitcoinBalanceChecker.checkBTC(
  'bc1qxy2kgdygjrsqtzq2n0yrf2493p83kkfjhx0wlh',
  'mempool.space'
);
console.log(`Balance: ${balance.balance} BTC`);

// Build transaction
const unsignedTx = await BitcoinTransactionBuilder.buildBTCTransaction(
  fromAddress,
  {
    toAddress: 'bc1qxy2kgdygjrsqtzq2n0yrf2493p83kkfjhx0wlh',
    amount: 100000, // 0.001 BTC in satoshis
    feeRate: 10, // satoshis per byte
    apiProvider: 'mempool.space',
  }
);

// Sign with Transaction.sign()
// Then broadcast to Bitcoin network

Dogecoin Support

import { DogecoinBalanceChecker, DogecoinTransactionBuilder } from 'expo-trust-core';

// Check balance
const balance = await DogecoinBalanceChecker.checkDOGE(
  'DH5yaieqoZN36fDVciNyRueRGvGLR3mr7L',
  'blockchair.com'
);
console.log(`Balance: ${balance.balance} DOGE`);

// Build transaction
const unsignedTx = await DogecoinTransactionBuilder.buildDOGETransaction(
  fromAddress,
  {
    toAddress: 'DH5yaieqoZN36fDVciNyRueRGvGLR3mr7L',
    amount: 100000000, // 1 DOGE in koinu
    feeRate: 100000, // 0.001 DOGE per byte
    apiProvider: 'blockchair.com',
  }
);

// Sign with Transaction.sign()
// Then broadcast to Dogecoin network

Native Transaction Signing (v1.0+)

Full Protobuf signing on iOS & Android - Private keys NEVER exposed to JavaScript!

import { Transaction, CoinType } from 'expo-trust-core';

// Ethereum transaction (Legacy)
const signedEthTx = await Transaction.sign(mnemonic, CoinType.Ethereum, {
  to: '0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb',
  value: '0x0de0b6b3a7640000', // 1 ETH in wei (hex)
  gasPrice: '0x04a817c800', // 20 gwei
  gasLimit: '0x5208', // 21000
  nonce: 0,
  chainId: 1, // Mainnet
  data: '0x',
}, 0); // account index
// Returns: "0x02f87..." ready to broadcast

// Ethereum EIP-1559
const signedEIP1559 = await Transaction.sign(mnemonic, CoinType.Ethereum, {
  to: '0x...',
  value: '0x0de0b6b3a7640000',
  gasLimit: '0x5208',
  nonce: 0,
  chainId: 1,
  maxFeePerGas: '0x77359400', // 2 gwei
  maxPriorityFeePerGas: '0x59682f00', // 1.5 gwei
  data: '0x',
}, 0);

// Solana transaction
const signedSolTx = await Transaction.sign(mnemonic, CoinType.Solana, {
  recentBlockhash: '11111111111111111111111111111111',
  recipient: 'DYw8jCTfwHNRJhhmFcbXvVDTqWMEVFBX6ZKUmG5CNSKK',
  amount: '1000000000', // 1 SOL in lamports
}, 0);
// Returns: Base64 signed transaction

// Bitcoin transaction (SegWit)
const signedBtcTx = await Transaction.sign(mnemonic, CoinType.Bitcoin, {
  utxos: [
    {
      txid: 'abc123...',
      vout: 0,
      value: 100000,
      scriptPubKey: '0014...'
    }
  ],
  toAddress: 'bc1qxy2kgdygjrsqtzq2n0yrf2493p83kkfjhx0wlh',
  amount: 50000,
  changeAddress: 'bc1q...',
  byteFee: 10,
}, 0);

Advanced: Sign Raw Transaction Hash

For custom transaction building workflows:

import { Transaction, CoinType } from 'expo-trust-core';
import { ethers } from 'ethers';

// 1. Build transaction externally
const unsignedTx = {
  to: '0x...',
  value: ethers.parseEther('1.0'),
  gasLimit: 21000,
  nonce: 0,
  chainId: 1,
};

// 2. Serialize to get hash
const serialized = ethers.Transaction.from(unsignedTx).unsignedSerialized;
const txHash = ethers.keccak256(serialized);

// 3. Sign hash natively (private key stays in native code!)
const signature = await Transaction.signRawTransaction(
  mnemonic,
  txHash,
  CoinType.Ethereum,
  0 // account index
);

// 4. Attach signature
const signedTx = ethers.Transaction.from({
  ...unsignedTx,
  signature,
}).serialized;

// 5. Broadcast
await provider.broadcastTransaction(signedTx);

React Hooks

import { useWallet, useAddress, useMessageSign } from 'expo-trust-core';

function MyWalletComponent() {
  const { wallet, createWallet, importWallet } = useWallet();
  const { generateAddress, addresses } = useAddress();
  const { signMessage, signTypedData } = useMessageSign();

  const handleCreateWallet = async () => {
    const newWallet = await createWallet();
    console.log('Mnemonic:', newWallet.mnemonic);
  };

  const handleGetAddress = async () => {
    const address = await generateAddress(CoinType.Ethereum, 0);
    console.log('Address:', address);
  };

  return (
    <View>
      <Button title="Create Wallet" onPress={handleCreateWallet} />
      <Button title="Get Address" onPress={handleGetAddress} />
    </View>
  );
}

Supported Blockchains

| Blockchain | Symbol | Coin Type | Address Type | |-----------|--------|-----------|--------------| | Bitcoin | BTC | 0 | SegWit (bc1...) | | Ethereum | ETH | 60 | EVM (0x...) | | Solana | SOL | 501 | Base58 | | Dogecoin | DOGE | 3 | Legacy (D...) | | Polygon | MATIC | 60 | EVM (0x...) | | Arbitrum | ARB | 60 | EVM (0x...) | | Base | BASE | 60 | EVM (0x...) | | BSC | BNB | 60 | EVM (0x...) | | Optimism | OP | 60 | EVM (0x...) | | Avalanche | AVAX | 60 | EVM (0x...) |

Note: All EVM chains use the same CoinType.Ethereum (60) for address derivation.

Architecture

expo-trust-core/
├── Native Layer (Trust Wallet Core)
│   ├── iOS (Swift)
│   └── Android (Kotlin)
├── TypeScript SDK
│   ├── Core Modules (Mnemonic, HDWallet, Address)
│   ├── Signing (Message, TypedData)
│   ├── Advanced (PrivateKey, PublicKey)
│   └── Blockchain Helpers (P2)
└── React Hooks

Key Principles:

RPC Agnostic: You control your infrastructure
No Hardcoded URLs: All RPC endpoints are user-provided
Universal EVM Support: Works with any EVM-compatible chain
Privacy First: All cryptographic operations happen locally

API Reference

Core Classes

Mnemonic - Generate & validate BIP39 mnemonics
HDWallet - Hierarchical deterministic wallet
Address - Multi-chain address generation
Message - Message signing (EIP-191, Solana)
TypedData - EIP-712 typed data signing
PrivateKey - Private key operations
PublicKey - Public key operations
SingleKeyWallet - Import from private key

Blockchain Helpers - EVM

BalanceChecker - Native balance queries
TokenChecker - ERC20 token operations
TransactionBuilder - Transaction construction

Blockchain Helpers - Solana

SolanaBalanceChecker - SOL balance queries
SolanaSPLChecker - SPL token operations
SolanaTransactionBuilder - Transaction construction

Security Best Practices

Never expose mnemonics - Store securely with expo-secure-store
Never log private keys - Even in development
Validate all addresses - Before sending transactions
Use HTTPS RPC endpoints - Protect data in transit
Test on testnet first - Before mainnet deployment

Troubleshooting

Error: crypto.getRandomValues() not supported

You need to add polyfills for Solana. See Installation section.

Error: Module not found

Make sure you've installed the package and restarted Metro bundler:

npm install
npx expo start --clear

iOS Build Issues

cd ios
pod install
cd ..
npx expo run:ios

Android Build Issues

cd android
./gradlew clean
cd ..
npx expo run:android

Platform Requirements

iOS: 13.0 or higher
Android: API level 21 (Android 5.0) or higher
React Native: 0.70 or higher
Expo: SDK 49 or higher

Performance

Address Generation: ~50ms (native)
Message Signing: ~100ms (native)
Balance Check: 200-500ms (network dependent)
Transaction Build: 300-800ms (network dependent)

License

MIT License - See LICENSE file for details.

Support

If you find this SDK helpful, consider supporting its development:

Author

George Popescu - GitHub

Published

Vulnerabilities

Links

Maintainers

Keywords

Readme

expo-trust-core

Features

Core Cryptography

Advanced Features

Native Transaction Signing (v1.0+)

Blockchain Integration Helpers

Installation

1. Install SDK

2. Install Required Dependencies

3. Install Solana Polyfills (Required)

4. Configure Polyfills

5. Platform-Specific Setup

Complete Dependency List

Generate Addresses

Sign Messages

Sign Typed Data (EIP-712)

Blockchain Integration

Check EVM Balance

Check ERC20 Token Balance

Build EVM Transaction

Check Solana Balance

Check SPL Token Balance

Bitcoin Support

Dogecoin Support

Native Transaction Signing (v1.0+)

Advanced: Sign Raw Transaction Hash

React Hooks

Supported Blockchains

Architecture

API Reference

Core Classes

Blockchain Helpers - EVM

Blockchain Helpers - Solana

Security Best Practices

Troubleshooting

Error: crypto.getRandomValues() not supported

Error: Module not found

iOS Build Issues

Android Build Issues

Platform Requirements

Performance

Links

License

Support

Author