Viem Integration

# Accounts and Keys

Reference for private key management, HD wallets, and message signing with viem.

## Private Key Account

### Basic Usage

```typescript
import { privateKeyToAccount } from 'viem/accounts';

// ⚠️ Anvil default test key #0 — NEVER use in production!
const account = privateKeyToAccount(
  '0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80'
);

console.log(account.address); // 0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266
```

### With WalletClient

```typescript
import { createWalletClient, http } from 'viem';
import { privateKeyToAccount } from 'viem/accounts';
import { mainnet } from 'viem/chains';

const account = privateKeyToAccount(process.env.PRIVATE_KEY as `0x${string}`);

const client = createWalletClient({
  account,
  chain: mainnet,
  transport: http(),
});
```

### Generate New Private Key

```typescript
import { generatePrivateKey, privateKeyToAccount } from 'viem/accounts';

const privateKey = generatePrivateKey();
const account = privateKeyToAccount(privateKey);

console.log('Private Key:', privateKey);
console.log('Address:', account.address);
```

---

## Mnemonic / HD Wallet

### Create Account from Mnemonic

```typescript
import { mnemonicToAccount } from 'viem/accounts';

// ⚠️ NEVER use test mnemonics with real funds! This is a well-known example phrase.
const account = mnemonicToAccount(
  'legal winner thank year wave sausage worth useful legal winner thank yellow'
);

console.log(account.address); // Default path: m/44'/60'/0'/0/0
```

### Custom Derivation Path

```typescript
import { mnemonicToAccount } from 'viem/accounts';

// Different account indices
const account0 = mnemonicToAccount(mnemonic, { addressIndex: 0 }); // m/44'/60'/0'/0/0
const account1 = mnemonicToAccount(mnemonic, { addressIndex: 1 }); // m/44'/60'/0'/0/1
const account2 = mnemonicToAccount(mnemonic, { addressIndex: 2 }); // m/44'/60'/0'/0/2

// Custom account path
const account = mnemonicToAccount(mnemonic, {
  accountIndex: 1, // m/44'/60'/1'/0/0
});

// Full custom path
const account = mnemonicToAccount(mnemonic, {
  path: "m/44'/60'/0'/1/5",
});
```

### Generate New Mnemonic

```typescript
import { generateMnemonic, english, mnemonicToAccount } from 'viem/accounts';

// Generate 12-word mnemonic
const mnemonic = generateMnemonic(english);

// Generate 24-word mnemonic
const mnemonic24 = generateMnemonic(english, 256);

const account = mnemonicToAccount(mnemonic);
```

### Other Languages

```typescript
import {
  generateMnemonic,
  english,
  spanish,
  french,
  italian,
  japanese,
  korean,
  simplifiedChinese,
  traditionalChinese,
  czech,
  portuguese,
} from 'viem/accounts';

const mnemonic = generateMnemonic(spanish);
```

---

## HD Key Derivation

### From Master Seed

```typescript
import { HDKey, hdKeyToAccount } from 'viem/accounts';

// From seed (Buffer/Uint8Array)
const hdKey = HDKey.fromMasterSeed(seed);
const account = hdKeyToAccount(hdKey);
```

### From Extended Key

```typescript
import { HDKey, hdKeyToAccount } from 'viem/accounts';

// From xpriv/xpub
const hdKey = HDKey.fromExtendedKey('xprv9s21ZrQH143K...');
const account = hdKeyToAccount(hdKey);
```

### Derive Child Keys

```typescript
import { HDKey, hdKeyToAccount } from 'viem/accounts';

const masterKey = HDKey.fromMasterSeed(seed);

// Derive specific path
const childKey = masterKey.derive("m/44'/60'/0'/0/0");
const account = hdKeyToAccount(childKey);

// Multiple accounts
const accounts = Array.from({ length: 10 }, (_, i) => {
  const child = masterKey.derive(`m/44'/60'/0'/0/${i}`);
  return hdKeyToAccount(child);
});
```

---

## Message Signing

### Personal Sign (EIP-191)

```typescript
import { privateKeyToAccount } from 'viem/accounts';

const account = privateKeyToAccount('0x...');

// Sign a message
const signature = await account.signMessage({
  message: 'Hello, World!',
});

// Sign raw bytes
const signature = await account.signMessage({
  message: { raw: '0x68656c6c6f' },
});
```

### Verify Message Si