Crypto Wallet

react-native-quick-crypto is the engine that powers many high-performance crypto wallets.

While it does not provide high-level wallet standards (like BIP39 wordlists) out of the box, it provides the fast cryptographic primitives (pbkdf2, hmac, randomBytes) that make wallet generation instant on mobile devices.

The Performance Bottleneck

Generating a wallet involves PBKDF2 (Password-Based Key Derivation Function 2) with 2048 iterations.

Pure JS: ~1500ms on older Android phones. ( Blocks UI )
RNQC: ~20ms. ( Instant )

Implementation

This guide shows how to implement the core cryptographic operations of a wallet manually using RNQC.

1. Generate Entropy (Randomness)

Every wallet starts with random data. We use the OS's cryptographically secure random number generator.

import { randomBytes } from 'react-native-quick-crypto';

const entropy = randomBytes(16);

In a full BIP39 implementation, you would convert this entropy into a list of 12 words using a standard wordlist.

2. Mnemonic to Seed (PBKDF2)

Converting the mnemonic (words) into a binary seed is the "heavy lifting". This is where RNQC shines.

import { pbkdf2 } from 'react-native-quick-crypto';

export function mnemonicToSeed(mnemonic: string, passphrase = ''): Promise<Buffer> {
  return new Promise((resolve, reject) => {
    const salt = 'mnemonic' + passphrase;
    
    // BIP39 Standard requires SHA-512, 2048 iterations, 64 bytes output
    pbkdf2(mnemonic, salt, 2048, 64, 'sha512', (err, key) => {
      if (err) return reject(err);
      resolve(key);
    });
  });
}

3. HD Key Derivation (HMAC-SHA512)

Once you have the seed, you derive child keys (for Bitcoin, Ethereum, etc) using HMAC-SHA512.

import { createHmac } from 'react-native-quick-crypto';

// A stripped-down example of BIP32 derivation
export function deriveChildKey(parentKey: Buffer, chainCode: Buffer, index: number) {
  const hmac = createHmac('sha512', chainCode);
  
  // Data = 0x00 || ParentKey || Index (BigEndian)
  const data = Buffer.alloc(37);
  data[0] = 0x00;
  parentKey.copy(data, 1);
  data.writeUInt32BE(index, 33);
  
  hmac.update(data);
  const I = hmac.digest();
  
  // Split I into Left (Private Key) and Right (Chain Code)
  const IL = I.subarray(0, 32);
  const IR = I.subarray(32);
  
  return { privateKey: IL, chainCode: IR };
}

Frequently Asked Questions

Do I need `bip39` libraries?

Yes, if you need the English Wordlist to convert random bytes into words like "horse battery staple". RNQC doesn't bundle dictionary files to keep the app size small.

You use a library like @scure/bip39 for the words, and configure it to use RNQC for the math (PBKDF2/SHA512) to get the best performance.

Hopefully, we will soon see a fully JSI-based BIP39 library for React Native that integrates directly with these primitives!