title: How to pass data securly between web sites?
body: <p>If I have a portal which i use to access other websites.</p>
  
  <p>Say I have a portal <code>A</code> . And I wanna to access the website <code>B</code>.</p>
  
  <p>If <code>B</code> needs some critical info to work like <code>username</code> . I wanna to pass these info securely . </p>
  
  <hr>
  
  <p>so i make form like this :</p>
  
  <pre><code> &lt;%--------------------------------------------------------------------------------------%&gt;
      &lt;form id="frm_sal" action="B URL the first page" method="post"&gt;
      &lt;input id="hdn_sal_Emp_Num" type="hidden" runat="server" name="hdn_sal_Emp_Num" /&gt;
      &lt;input id="hdn_sal_user_name" type="hidden" runat="server" name="hdn_sal_user_name" /&gt;
      &lt;input id="hdn_sal_result" type="hidden" runat="server" name="hdn_sal_result" /&gt;
      &lt;/form&gt;
    &lt;%--------------------------------------------------------------------------------------%&gt;
  </code></pre>
  
  <p>and in the event client click of a link in the portal <code>A</code> , i will submit to this form .</p>
  
  <p>One form for each website.</p>
  
  <p>My question is about How to secure those data and prevent Tampering.</p>