Simple AES string encrypt/decrypt

aes-string-crypto.js

// Simple AES encryption and decryption
// The password should be of high complexity
// as it is just pashed through a SHA256 before
// it is used to encrypt/decrypt

async function encrypt(message, password) {
	let iv = window.crypto.getRandomValues(new Uint8Array(12));
	let alg = {name: "AES-GCM", iv: iv};
	let pwHash = await window.crypto.subtle.digest('SHA-256', new TextEncoder().encode(password));
	let key = await window.crypto.subtle.importKey('raw', pwHash, alg, false, ['encrypt']);
	let cipher = await window.crypto.subtle.encrypt(
		{name: "AES-GCM", iv: iv},
		key,
		new TextEncoder().encode(message)
	);
	let r = new Uint8Array(iv.byteLength + cipher.byteLength);
	r.set(new Uint8Array(iv), 0);
	r.set(new Uint8Array(cipher), iv.byteLength);
	return r.buffer;
}

async function decrypt(cipher, password) {
	cipher = new Uint8Array(cipher);
	let iv = cipher.slice(0, 12).buffer;
	let alg = {name: "AES-GCM", iv: iv};
	let pwHash = await window.crypto.subtle.digest('SHA-256', new TextEncoder().encode(password));
	let key = await window.crypto.subtle.importKey('raw', pwHash, alg, false, ['decrypt']);
	try {
		let message = await window.crypto.subtle.decrypt(
			{name: "AES-GCM", iv: iv},
			key,
			cipher.slice(12, cipher.length).buffer
		);
		return new TextDecoder().decode(message);
	} catch (e) {
		return null;
	}
}