init.ts

// This code is used to init the private key of the server in order to encrypt the localStorage data.
// Note : The key is not used to encrypt the user data, it is used to encrypt the localStorage data.
// The user data is encrypted using the user password. The user password is used to encrypt the localStorage data.

//Check locally if the key is already generated `server.key`
// If not, generate a new key and save it locally
import { base64ToBytesArr } from "./utils.ts";
try {
  Deno.statSync("./server.key");
  console.log("The key is already generated");
  const res = prompt(
    "Say OK to regenerate the key, warning this will delete all the data\n\r",
  );
  if (res === "OK") {
    Deno.removeSync("./server.key");
    console.log("The key has been deleted");
  } else {
    console.log("Exiting");
    Deno.exit(1);
  }
} catch {
  //
}

localStorage.clear();
const smtpData = localStorage.getItem("smtpData") ?? "{}";

//prompt user for the KEY to use to generate the key
const PASSWORD = prompt(
  "Enter a secret phrase to generate the key (please make it dificult to recreate!) \n\r",
);
if (!PASSWORD) {
  console.log("Empty secret phrase, Exiting");
  Deno.exit(1);
}
if (PASSWORD.length < 8) {
  console.log("The secret phrase is too short, Exiting");
  Deno.exit(1);
}
const iv = crypto.getRandomValues(new Uint8Array(12));
const KEY_FROM = await window.crypto.subtle.importKey(
  "raw",
  new TextEncoder().encode(PASSWORD),
  "PBKDF2",
  false,
  ["deriveBits", "deriveKey"],
);
const salt = window.crypto.getRandomValues(new Uint8Array(16));

const DERIVED_KEY = await window.crypto.subtle.deriveKey(
  { "name": "PBKDF2", salt: salt, "iterations": 100000, "hash": "SHA-512" },
  KEY_FROM,
  { "name": "AES-GCM", "length": 256 },
  true,
  ["encrypt", "decrypt"],
);
//save the salt and iv in the localStorage
localStorage.setItem(
  "salt",
  btoa(salt.reduce((data, byte) => data + String.fromCharCode(byte), "")),
);
localStorage.setItem(
  "iv",
  btoa(iv.reduce((data, byte) => data + String.fromCharCode(byte), "")),
);
//save the key in a file
const keydata = await crypto.subtle.exportKey("raw", DERIVED_KEY);
await Deno.writeFile("./server.key", new Uint8Array(keydata), { mode: 0o600 });

const data = await window.crypto.subtle.encrypt(
  { name: "AES-GCM", iv: iv },
  DERIVED_KEY,
  new TextEncoder().encode(smtpData),
);
const buffer = new Uint8Array(data);
const base64String = btoa(
  buffer.reduce((data, byte) => data + String.fromCharCode(byte), ""),
);
localStorage.setItem("smtpData", base64String);

try {
  const keydata_file = Deno.readFileSync("./server.key");
  const keydata_import = await window.crypto.subtle.importKey(
    "raw",
    keydata_file,
    "AES-GCM",
    true,
    ["encrypt", "decrypt"],
  );
  const iv_s = base64ToBytesArr(localStorage.getItem("iv")!);
  const decodedbuffer = base64ToBytesArr(base64String);
  const data_decoded = await window.crypto.subtle.decrypt(
    { name: "AES-GCM", iv: new Uint8Array(iv_s) },
    keydata_import,
    new Uint8Array(decodedbuffer),
  );
  console.log(new TextDecoder().decode(data_decoded));
} catch (e) {
  console.error(
    "Error while decrypting the data, deleting the key and the data",
  );
  Deno.removeSync("./server.key");
  localStorage.clear();
  console.error(e);
}