simple-secure-webcrypto

This Simple Secure WebCrypto library was created to make it easy to do symmetric encryption and decryption of strings using the Web Crypto API, which provides the SubtleCrypto interface with low-level cryptographic functions.

Features

✅ Zero package dependencies - exclusively uses WebCrypto API.

✅ Works on browser platforms like Cloudflare Workers.

✅ Secure defaults; uses AES-GCM (authenticated encryption) with a 256 bit key.

✅ Written in TypeScript.

Who is this library for?

If you're a developer building on platforms such as Cloudflare Pages or Cloudflare Workers and want to easily encrypt and decrypt some data with just an secret from an environment variable, this library provides a simple interface to do so.

Usage

Install via your package manager:

bun install simple-secure-webcrypto

Then invoke the async encrypt and decrypt functions:

import { encrypt, decrypt } from "simple-secure-webcrypto";

const someData = "hello world";
try {
    const encrypted = await encrypt(env.ENCRYPTION_SECRET, someData);
    const decrypted = await decrypt(env.ENCRYPTION_SECRET, encrypted);
} catch (error) {
    console.log(error);
}

Note: the decrypt function will throw an error if the encrypted data is in an invalid format.

To generate a new random encryption secret key, we created the genkey.ts helper:

import { generateKey } from "./src/index";
console.log(await generateKey());

which you can run from this repository root with:

bun run ./genkey.ts

How does it work?

Under the hood the SubtleCrypto interface provides encryption and decryption functions which support multiple algorithms.

The encrypted string returns from our encrypt function will be encoded as iv.ciphertext where:

• IV is the base64 encoded Initialization Vector (IV) aka nonce, randomly generated on each encrypt function invocation.

• Ciphertext is the base64 encoded AES-GCM encrypted value.

The returned string can safely be stored in a database or cookie; AES-GCM uses authenticated encryption, which will fail if either the ciphertext or IV cannot be verified, per Appendix B: Authentication Assurance in NIST SP 800-38D.

License

MIT

Credit

Thank you to Nadrama.com for sponsoring this work! Nadrama enables you to run a Kubernetes PaaS in your cloud account, in minutes.

References

• MDN Web Crypto API documentation

• MDN Example AES-GCM implementation

• MDN SubtleCrypto supported algorithms

• Cloudflare Web Crypto supported algorithms

• NIST SP 800-38D: AES in Galois/Counter Mode

Development

We're using TypeScript, Bun, Bun test, Prettier, and ESLint.

To install dev dependencies:

bun install

To run prettier and eslint:

bun run pretty
bun run lint

To run tests:

bun test

To build:

bun run build

Security

Please reach out to Nadrama or @ryan0x44 if you have any security related questions or concerns.