Universal Asymmetric Cryptography Data Exchange Utils

A comprehensive TypeScript library for asymmetric cryptography operations using the Web Crypto API. This library provides easy-to-use functions for RSA key generation, encryption, and decryption that work universally across all modern JavaScript runtimes.

🌍 Universal Compatibility

✅ Node.js 16+ (with Web Crypto API)
✅ Browsers (Chrome, Firefox, Safari, Edge)
✅ Cloudflare Workers
✅ Deno
✅ Bun
✅ Web Workers & Service Workers

Features

• 🔐 RSA Key Pair Generation: Create public and private key pairs (CryptoKey & PEM formats)
• 🔒 Public Key Encryption: Encrypt data using public keys (RSA-OAEP)
• 🔓 Private Key Decryption: Decrypt data using private keys
• 📦 TypeScript Support: Full TypeScript support with type definitions
• 🚀 Multiple Formats: CommonJS and ES Module support
• 🛡️ Secure: Uses Web Crypto API with industry-standard algorithms
• ⚡ Async/Promise-based: Modern async API for better performance

Installation

npm install asymmetric-cryptography-data-exchange-utils

Quick Start

Modern Web Crypto API (CryptoKey format)

import {
  createKeys,
  encryptWithPubKey,
  decryptWithPrivateKey,
} from "asymmetric-cryptography-data-exchange-utils";

// 1. Generate a key pair (CryptoKey format)
const keyPair = await createKeys(2048);

// 2. Encrypt with public key, decrypt with private key
const message = "Hello, World!";
const encrypted = await encryptWithPubKey(message, keyPair.publicKey);
const decrypted = await decryptWithPrivateKey(encrypted, keyPair.privateKey);

console.log(decrypted); // "Hello, World!"

PEM Format (Node.js-style compatibility)

import {
  createKeysPEM,
  encryptWithPubKeyPEM,
  decryptWithPrivateKeyPEM,
} from "asymmetric-cryptography-data-exchange-utils";

// 1. Generate a key pair (PEM format)
const keyPair = await createKeysPEM(2048);

// 2. Encrypt with public key PEM, decrypt with private key PEM
const message = "Hello, World!";
const encrypted = await encryptWithPubKeyPEM(message, keyPair.publicKey);
const decrypted = await decryptWithPrivateKeyPEM(encrypted, keyPair.privateKey);

console.log(decrypted); // "Hello, World!"

API Reference

CryptoKey API (Recommended)

createKeys(keySize?: number): Promise<KeyPair>

Creates a new RSA key pair using Web Crypto API.

Parameters:

• keySize (optional): The size of the key in bits. Default: 2048

Returns:

• Promise<KeyPair>: Object containing publicKey and privateKey as CryptoKey objects

Example:

const keyPair = await createKeys(2048);
console.log(keyPair.publicKey.type); // "public"
console.log(keyPair.publicKey.algorithm); // { name: "RSA-OAEP", ... }

encryptWithPubKey(data: string | ArrayBuffer, publicKey: CryptoKey): Promise<EncryptedData>

Encrypts data using a public CryptoKey (RSA-OAEP padding).

Parameters:

• data: The string or ArrayBuffer data to encrypt
• publicKey: The public CryptoKey

Returns:

• Promise<EncryptedData>: Object with encrypted ArrayBuffer data

Example:

const encrypted = await encryptWithPubKey("secret message", keyPair.publicKey);
console.log(encrypted.data); // ArrayBuffer

decryptWithPrivateKey(encryptedData: EncryptedData, privateKey: CryptoKey): Promise<string>

Decrypts data using a private CryptoKey.

Parameters:

• encryptedData: The encrypted data object
• privateKey: The private CryptoKey

Returns:

• Promise<string>: The decrypted message

PEM API

createKeysPEM(keySize?: number): Promise<KeyPairPEM>

Creates a new RSA key pair and exports them as PEM strings.

Returns:

• Promise<KeyPairPEM>: Object containing publicKey and privateKey as PEM strings

encryptWithPubKeyPEM(data: string, publicKeyPEM: string): Promise<{data: string, encoding: 'base64'}>

Encrypts data using a public key PEM string.

decryptWithPrivateKeyPEM(encryptedData: {data: string, encoding: 'base64'}, privateKeyPEM: string): Promise<string>

Decrypts data using a private key PEM string.

Type Definitions

interface KeyPair {
  publicKey: CryptoKey;
  privateKey: CryptoKey;
}

interface KeyPairPEM {
  publicKey: string;
  privateKey: string;
}

interface EncryptedData {
  data: ArrayBuffer;
}

Platform-Specific Usage

Node.js

import { createKeys } from "asymmetric-cryptography-data-exchange-utils";

// Works with Node.js 16+ Web Crypto API
const keyPair = await createKeys();

Browser

<script type="module">
  import { createKeys } from "https://esm.sh/asymmetric-cryptography-data-exchange-utils";

  const keyPair = await createKeys();
  console.log("Crypto in browser!", keyPair);
</script>

Cloudflare Workers

// worker.js
import {
  createKeys,
  encryptWithPubKey,
} from "asymmetric-cryptography-data-exchange-utils";

export default {
  async fetch(request, env, ctx) {
    const keyPair = await createKeys();
    const encrypted = await encryptWithPubKey(
      "Hello from CF Workers!",
      keyPair.publicKey
    );

    return new Response(
      JSON.stringify({
        success: true,
        keyType: keyPair.publicKey.type,
      })
    );
  },
};

Deno

import { createKeys } from "npm:asymmetric-cryptography-data-exchange-utils";

const keyPair = await createKeys();
console.log("Crypto in Deno!", keyPair.publicKey.type);

Common Use Cases

1. Secure Message Exchange

// Alice creates a key pair
const aliceKeys = await createKeys();

// Bob encrypts a message for Alice using her public key
const message = "Secret information for Alice";
const encrypted = await encryptWithPubKey(message, aliceKeys.publicKey);

// Alice decrypts the message using her private key
const decrypted = await decryptWithPrivateKey(encrypted, aliceKeys.privateKey);

2. Cross-Platform Data Exchange

// Server (Node.js) generates keys
const serverKeys = await createKeysPEM();

// Send public key to client (browser/worker)
// Client encrypts data
const clientData = await encryptWithPubKeyPEM(
  "sensitive data",
  serverKeys.publicKey
);

// Server decrypts
const serverDecrypted = await decryptWithPrivateKeyPEM(
  clientData,
  serverKeys.privateKey
);

Development

Testing

# Run all tests
npm test

# Run tests in watch mode
npm run test:watch

# Run tests with coverage
npm run test:coverage

The library includes comprehensive Jest tests with high code coverage, testing all cryptographic operations, error handling, and edge cases across different API formats.

Example Usage

# Run the basic usage example
npm run example

Security Notes

• Key Size: Use at least 2048 bits for production use (4096 bits recommended for high security)
• Algorithm: Uses RSA-OAEP with SHA-256 for encryption
• Key Storage: Store private keys securely and never expose them in client-side code
• Message Size: RSA encryption has size limits based on key size and padding (~190 bytes for 2048-bit keys)
• Performance: Key generation is computationally expensive; consider caching keys when appropriate

Platform Compatibility Matrix

Platform	Web Crypto API	CryptoKey Support	PEM Support	Status
Node.js 16+	✅	✅	✅	Full Support
Chrome/Edge	✅	✅	✅	Full Support
Firefox	✅	✅	✅	Full Support
Safari	✅	✅	✅	Full Support
Cloudflare Workers	✅	✅	✅	Full Support
Deno	✅	✅	✅	Full Support
Bun	✅	✅	✅	Full Support
Web Workers	✅	✅	✅	Full Support

Migration from Node.js crypto

If you're migrating from the Node.js crypto module:

Before (Node.js crypto)

import { generateKeyPairSync, publicEncrypt, privateDecrypt } from "crypto";

const { publicKey, privateKey } = generateKeyPairSync("rsa", {
  modulusLength: 2048,
  publicKeyEncoding: { type: "spki", format: "pem" },
  privateKeyEncoding: { type: "pkcs8", format: "pem" },
});

const encrypted = publicEncrypt(publicKey, Buffer.from(message));
const decrypted = privateDecrypt(privateKey, encrypted).toString();

After (Universal Web Crypto)

import {
  createKeysPEM,
  encryptWithPubKeyPEM,
  decryptWithPrivateKeyPEM,
} from "asymmetric-cryptography-data-exchange-utils";

const { publicKey, privateKey } = await createKeysPEM(2048);

const encrypted = await encryptWithPubKeyPEM(message, publicKey);
const decrypted = await decryptWithPrivateKeyPEM(encrypted, privateKey);

Requirements

• Node.js >= 16.0.0 (for Web Crypto API support)
• Modern browsers with Web Crypto API support
• TypeScript (for development)

Scripts

• npm run build - Build the library for production
• npm run dev - Build in watch mode for development
• npm test - Run Jest tests
• npm run test:watch - Run tests in watch mode
• npm run test:coverage - Run tests with coverage report
• npm run example - Run the usage example

License

MIT

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.