expo-crypto-lib

Standalone Expo module providing hybrid RSA + AES encryption with mnemonic-based key derivation for React Native / Expo and Node.

This is a JavaScript-only module; it has no native iOS/Android code and does not require prebuild hooks.

Requirements: Node 18+ for local development and tests. For Expo/React Native apps: Expo SDK 50+ (or compatible), plus peer dependencies below.

Install

npm install expo-crypto-lib

With Expo, ensure peer dependencies are installed (they usually are in an Expo project):

npx expo install expo-crypto expo-secure-store

Quick start

Expo / React Native (one-line manager)

import { createRSAManager } from 'expo-crypto-lib';
import { Platform } from 'react-native';

const manager = createRSAManager({ platform: 'expo', platformOS: Platform.OS });
await manager.generateRSAKeypair(2048);
const encrypted = await manager.encryptDataForLocalStorage(fileBytes);
const decrypted = await manager.decryptDataFromLocalStorage(encrypted);

Node (or tests)

const { createRSAManager } = require('expo-crypto-lib');

const manager = createRSAManager({ platform: 'node' });
await manager.generateRSAKeypair(2048);
const encrypted = await manager.encryptDataForLocalStorage(data);
const decrypted = await manager.decryptDataFromLocalStorage(encrypted);

You can also build the manager manually with EnhancedRSAManager, createExpoKeyStorage / createNodeKeyStorage, and createExpoRandomValues / createNodeRandomValues (see GETTING_STARTED.md).

Features

• RSA (2048/3072-bit, OAEP) + AES-256-CBC hybrid encryption for data and keys
• Mnemonic (24-word BIP39-like) generation and seed derivation for deterministic key recovery
• Adapters for Expo (expo-secure-store, expo-crypto) and Node (in-memory + crypto.getRandomValues)
• Optional React Native performance: use expo-crypto-lib/react-native and applyForgeOptimization() with react-native-modpow

Troubleshooting

• Module not found: expo-secure-store (or expo-crypto): You are using the Expo adapters in an Expo/React Native app but the peer packages are not installed. Run:

  npx expo install expo-secure-store expo-crypto

  Import from expo-crypto-lib (the main entry), not from expo-crypto-lib/react-native, unless you specifically need applyForgeOptimization.

• Error in Node when using createExpoKeyStorage: The Expo adapters are for React Native/Expo only. In Node or tests, use createNodeKeyStorage() and createNodeRandomValues().

Docs

• GETTING_STARTED.md — Install, build, usage examples, API summary, dependencies
• PUBLISHING.md — How to publish the package (npm, GitHub Packages)

Source: https://github.com/mryan-iadeptive/expo-crypto-lib

License

MIT

Maintained by Matthew Ryan @ HonestTech