Rocket.Chat/app/livechat/client/externalFrame/crypto.ts

function ab2str(buf: ArrayBuffer): string {
	return String.fromCharCode(...new Uint16Array(buf));
}

function str2ab(str: string): ArrayBuffer {
	const buf = new ArrayBuffer(str.length * 2); // 2 bytes for each char
	const bufView = new Uint16Array(buf);
	for (let i = 0, strLen = str.length; i < strLen; i++) {
		bufView[i] = str.charCodeAt(i);
	}
	return buf;
}

export async function generateKey(): Promise<string> {
	const key = await crypto.subtle.generateKey({ name: 'AES-GCM', length: 256 }, true, ['encrypt', 'decrypt']);
	const exportedKey = await crypto.subtle.exportKey('jwk', key);
	return JSON.stringify(exportedKey);
}

export async function getKeyFromString(keyStr: string): Promise<CryptoKey> {
	const key = JSON.parse(keyStr);
	return crypto.subtle.importKey('jwk', key, { name: 'AES-GCM', length: 256 }, true, ['encrypt', 'decrypt']);
}

export async function encrypt(text: string, key: CryptoKey): Promise<string> {
	const vector = crypto.getRandomValues(new Uint8Array(16));
	const data = new TextEncoder().encode(text);
	const enc = await crypto.subtle.encrypt({ name: 'AES-GCM', iv: vector }, key, data);
	const cipherText = new Uint8Array(enc);
	return encodeURIComponent(btoa(ab2str(vector) + ab2str(cipherText)));
}

export async function decrypt(data: string, key: CryptoKey): Promise<string> {
	const binaryData = atob(decodeURIComponent(data));
	const vector = new Uint8Array(new Uint16Array(str2ab(binaryData.slice(0, 16))));
	const buffer = new Uint8Array(new Uint16Array(str2ab(binaryData.slice(16))));
	const decoded = await crypto.subtle.decrypt({ name: 'AES-GCM', iv: vector }, key, buffer);
	return new TextDecoder().decode(decoded);
}