title: php error: The Encrypt library requires the Mcrypt extension in codeigniter
body: <p>I have a login and sign up form and use the encrypt library to encrypt the password.. I am using Xampp for my server and my system works correctly..</p>
  
  <p>code to encrypt the password:</p>
  
  <pre><code>$this-&gt;encrypt-&gt;encode('my password'); 
  </code></pre>
  
  <p>add encrypt library </p>
  
  <pre><code> $autoload['libraries'] = array('encrypt');
  </code></pre>
  
  <p>and setting the secret key in config:</p>
  
  <pre><code>$config['encryption_key'] = 'nmsc encrypt secret key';
  </code></pre>
  
  <p>My code works well using xampp server in windows but when Im trying to upload my website to ubuntu server I've got an error says </p>
  
  <blockquote>
    <p>The Encrypt library requires the Mcrypt extension</p>
  </blockquote>
  
  <p>how to fix that problem? refering this guide <a href="https://www.codeigniter.com/user_guide/libraries/encryption.html" rel="noreferrer">https://www.codeigniter.com/user_guide/libraries/encryption.html</a> but I dont know how to install that mcrypt. my website needs to run from ubuntu server. how to install or fix that problem?</p>