Usage: this implementation would be invoked as follows:

  var password = 'L0ck it up saf3';
  var plaintext = 'pssst ... đon’t tell anyøne!';
  var ciphertext = Aes.Ctr.encrypt(plaintext, password, 256);
  var origtext = Aes.Ctr.decrypt(ciphertext, password, 256);