If I have a portal which i use to access other websites.

Say I have a portal `A` . And I wanna to access the website `B`.

If `B` needs some critical info to work like `username` . I wanna to pass these info securely . 

---

so i make form like this :

```
 <%--------------------------------------------------------------------------------------%>
    <form id="frm_sal" action="B URL the first page" method="post">
    <input id="hdn_sal_Emp_Num" type="hidden" runat="server" name="hdn_sal_Emp_Num" />
    <input id="hdn_sal_user_name" type="hidden" runat="server" name="hdn_sal_user_name" />
    <input id="hdn_sal_result" type="hidden" runat="server" name="hdn_sal_result" />
    </form>
  <%--------------------------------------------------------------------------------------%>

```

and in the event client click of a link in the portal `A` , i will submit to this form .

One form for each website.

My question is about How to secure those data and prevent Tampering.