persistentState.js

import { fromJS } from 'immutable';
import sjcl from 'sjcl';

/*
 * This function gets the encrypted object from the session storage,
 * decrypt it and set the state back into the store.
 */
export function recoverStateFromSession(key, state, password) {
  const encryptedData = JSON.parse(sessionStorage.getItem(key));
  if(!encryptedData) { return state; }

  const json = sjcl.decrypt(password, encryptedData);
  const data = JSON.parse(json);
  return state.set(key, fromJS(data));
}

/*
 * Saves the state locally in session storage.
 */
export function saveStateInSession(key, data, password) {
  const encryptedData = sjcl.encrypt(password, JSON.stringify(data));
  sessionStorage.setItem(key, JSON.stringify(encryptedData));
}