Delphi7 - Encrypted User Logon to Domain Controller over Network

Create small Delphi 7 application which allows logging onto a domain controller (windows Server 2003) with an encrypted password. Problem: the function LogonUser (win 32 function) which I currently used, sends the password as plain text to the domain controller. Therefor I need another function which allows the sending of the encrypted password. However I have no idea which function to use. When bidding for this project kindly indicated which function you are planning to use. If possible kindly also indicated a way how I can verify that the password is indeed transmitted encrypted and not as plain text. - Delphi 7 (Build 4.453) - Domain controller (windows Server 2003) no exchange server used - Operating system on which the application / logon is going to be used is Windows XP embedded