title: How do I replace column after encrypting it by using Spark (PySpark)?
body: <p>I have a question about replacing personal information to encrypted data using Spark.</p>
  <p>Let's say for example, if I have a table like:</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>std_name</th>
  <th>phone_number</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>John</td>
  <td>585-1243-2156</td>
  </tr>
  <tr>
  <td>Susan</td>
  <td>585-4567-2156</td>
  </tr>
  </tbody>
  </table>
  </div>
  <p>I want to change phone_number to encrypted form like:</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>std_name</th>
  <th>phone_number</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>John</td>
  <td>avawehna'vqqa</td>
  </tr>
  <tr>
  <td>Susan</td>
  <td>vabdsvwegq'qb</td>
  </tr>
  </tbody>
  </table>
  </div>
  <p>I have tried using <code>withColumn</code> with <code>udf</code>, but it does not work well.
  Can someone help me out?</p>