const key = await window.crypto.subtle.generateKey(
    {
      name: "AES-GCM",
      length: 256
    },
    true,
    ["encrypt", "decrypt"]
  );

  const note = "A very secret note";
  const noteBuffer = new TextEncoder("utf-8").encode(note);

  const nonce = window.crypto.getRandomValues(new Uint8Array(12));

  const cyphertext = await window.crypto.subtle.encrypt(
    {
      name: "AES-GCM",
      iv: nonce
    },
    key,
    noteBuffer
  );

   const plaintext = await window.crypto.subtle.decrypt(
    {
      name: "AES-GCM",
      iv: nonce
    },
    key,
    cyphertext
  );

  const decoder = new TextDecoder("utf-8");
  const decryptedNote = decoder.decode(new Uint8Array(plaintext));

  console.log(decryptedNote); // A very secret note

  const password = "The user's secret password"
  const enc = new TextEncoder();

  const passwordAsKey = await window.crypto.subtle.importKey(
    "raw",
    enc.encode(password),
    {name: "PBKDF2"},
    false,
    ["deriveBits", "deriveKey"]
  );

  const salt = window.crypto.getRandomValues(new Uint8Array(12));

  const key = await window.crypto.subtle.deriveKey(
    {
      name: "PBKDF2",
      salt: salt,
      iterations: 100000,
      hash: "SHA-256"
    },
    passwordAsKey,
    { name: "AES-GCM", length: 256},
    true,
    [ "encrypt", "decrypt" ]
  );

const keyPair = window.crypto.subtle.generateKey(
  {
    name: "RSA-OAEP",
    modulusLength: 4096,
    publicExponent: new Uint8Array([1, 0, 1]),
    hash: "SHA-256"
  },
  true,
  ["encrypt", "decrypt"]
);