Allow an external web site to automatically login to an ASP.Net si

[Tim]

Hi

I have a requirement for an external web site to be able to automatically
log in to my ASP.Net web site that is managed using Forms Authentication

To do this I have created a simple HTML Form, that submits a userId and
password as a Form Post submission to my ASP.Net web site that can then
process it

The problem is the HTML Form passes the userId and password UNENCRYPTED
which is not secure

- The question is, how can I pass the userId and password in an ENCRYPTED
way to my ASP.Net application?

I am thinking of some sort of web service call to get a GUID, which will
then act as a temporary Id to my site, but I am not sure how the web service
can receive authentication details that are encrypted?

Thanks in advance for advice on this matter