How to mask External input field with *****?

Hi Boaders,
Can anyone help with code to mask the external input value with " * " sign? The reason is because i wanted to password protect my EA for distribution. My current code is this;

extern string Please_Enter_Password="0";

You can't do that as far as I know.

But a quick alternative solution that I thought of is to 1) ecnrypt your password/authentication code along with user data in a file, 2) send the encrypted file by mail to the user and 3) the user places the file in the MT /files folder where you can open it and validate the contents etc...