Password confirmation dialog

I'm trying to create a custom password confirmation dialog in navision. The purpose of this is for a manager to authorize a process while another user is logged in. However, I can't seem to match the supplied password hash to the stored one in navision. I'm currently using an input dialog box to get the password but that will probably be changed for security later. Here's the code I'm using so far ('Login' is the Navision User table)

   Prompt.OPEN('Only managers can void a sale.\'+
               'Please enter login credentials\'+
               'User:     #1##############\'+
               'Password: #2##############');
   Prompt.INPUT(1,UserName);
   Prompt.INPUT(2,Passw);
   Prompt.CLOSE;
   Login.INIT;
   Login.VALIDATE(Password,Passw);
   Hash := Login.Password;
   IF NOT Login.GET(UserName) THEN
      ERROR('User %1 does not exist!',UserName);
   MESSAGE(Login.Password);
   IF (Login.Password = Hash) THEN
   BEGIN
      'do some stuff
   END ELSE
      ERROR('Incorrect password for user %1',UserName);

I'm assuming that navision must padd the password in some manner before it hashes it. Can anyone tell me what I need to do here? :twisted: