expo-crypto-universal

A universal crypto implementation for Expo that works across all platforms, including web. This package provides a consistent interface for crypto operations that can be implemented differently based on the platform.

Features

• Platform-agnostic crypto interface
• SHA-2 hashing (256, 384, 512 bits)
• Secure random bytes generation
• TypeScript support
• Platform detection utility
• Separate implementations for Web and Native platforms

Installation

# Install the main package
npm install expo-crypto-universal
# or
yarn add expo-crypto-universal

# Install platform-specific implementation
npm install expo-crypto-universal-web    # For web platform
npm install expo-crypto-universal-native # For native platforms (iOS/Android)

Dependencies

This package requires one of the following platform-specific implementations:

• expo-crypto-universal-web for web platform
• expo-crypto-universal-native for native platforms (iOS/Android)

Usage

import { isWeb } from 'expo-crypto-universal';
import { WebCryptoModule } from 'expo-crypto-universal-web';
import { NativeCryptoModule } from 'expo-crypto-universal-native';

// Get the appropriate crypto module for your platform
const crypto = isWeb() ? new WebCryptoModule() : new NativeCryptoModule();

// Generate random bytes
const randomBytes = crypto.getRandomBytes(32);

// Generate SHA-256 hash
const data = new TextEncoder().encode('Hello, World!');
const hash256 = await crypto.sha256Async(data);

// Generate SHA-384 hash
const hash384 = await crypto.sha384Async(data);

// Generate SHA-512 hash
const hash512 = await crypto.sha512Async(data);

// Or use the generic SHA-2 method
const hash = await crypto.sha2Async(256, data); // Same as sha256Async

API

isWeb()

Returns true if the current environment is a web environment, false otherwise.

CryptoModule Interface

The package exports a CryptoModule interface that defines the contract for crypto implementations:

interface CryptoModule {
  getRandomValues(values: Uint8Array): Uint8Array;
  getRandomBytes(size: number): Uint8Array;
  sha256Async(data: Uint8Array): Promise<Uint8Array>;
  sha384Async(data: Uint8Array): Promise<Uint8Array>;
  sha512Async(data: Uint8Array): Promise<Uint8Array>;
  sha2Async(bits: number, data: Uint8Array): Promise<Uint8Array>;
}

getRandomValues(values: Uint8Array): Uint8Array

Fills the provided Uint8Array with cryptographically secure random values.

getRandomBytes(size: number | undefined): Uint8Array

Generates a new Uint8Array of specified size filled with cryptographically secure random bytes. If no size is specified, it defaults to 32 bytes.

sha256Async(data: Uint8Array): Promise<Uint8Array>

Computes the SHA-256 hash of the input data.

sha384Async(data: Uint8Array): Promise<Uint8Array>

Computes the SHA-384 hash of the input data.

sha512Async(data: Uint8Array): Promise<Uint8Array>

Computes the SHA-512 hash of the input data.

sha2Async(bits: number, data: Uint8Array): Promise<Uint8Array>

Computes the SHA-2 hash of the input data with the specified number of bits (256, 384, or 512).

Platform Support

The package provides platform-specific implementations:

• Web: expo-crypto-universal-web using Web Crypto API
• Native (iOS/Android): expo-crypto-universal-native using Expo's native crypto implementation

Testing

The package is designed to work seamlessly with Vitest. No special configuration is required as the platform-specific implementations are now separate packages.

License

MIT