Question

How to use windows authentication (local machine administrator user) in windows application written in C#.

Need is whenever user opens my windows application GUI, it should authenticate local administrator credentials even if User is logged in as Administrator there.

Is this windows Impersonation?

Answer 1

You can call the LogonUser API method to check a username and password.
You can see the [DllImport] here.

If you want to show a standard username/password prompt, you can call the CredUIPromptForCredentials API function; see also here

EDIT

To check whether the user is an administrator, you can call CheckTokenMembership and check whether the user is in the Administrators group.

Alternatively, you can call NetUserGetInfo level 1 and check whether usri1_priv is USER_PRIV_ADMIN.

You can also use WMI or DirectoryServices.