title: Can cookies be shared between subdomains over SSL on different servers?
body: <p>We are evaluating feasibility of the following solution for Single Sign On.</p>
  
  <p>Scenario.
  Website domain. <a href="https://www.example.com" rel="nofollow">https://www.example.com</a>  </p>
  
  <ul>
  <li>[SSL using multi-server wildcard certificate]</li>
  <li>Hosted on Server 1.</li>
  </ul>
  
  <p>Other portal. <a href="https://portal.example.com" rel="nofollow">https://portal.example.com</a> </p>
  
  <ul>
  <li>[SSL using the same certificate (multi-server wildcard certificate)]</li>
  <li>Hosted on Server 2.</li>
  </ul>
  
  <p>Solution:
  The intention is to share a cookie between the www.example.com and the portal.example.com subdomains, however, for this to work the SSL protocol needs to satisfy the following requirements:</p>
  
  <ul>
  <li>Continue to block Man-in-the-middle attacks.</li>
  <li>Encrypt/Decrypt in the same manner for both Server 1 and Server 2. So that they can get the same information from the cookie.</li>
  </ul>
  
  <p>Question is: Is there any limitations in terms of private keys or the SSL protocol perse that will make the solution above not feasible?</p>
  
  <p>Thanks,</p>