function EncryptFile(lpFilename: PChar): BOOL; stdcall;
external advapi32 name 'EncryptFileA';

function DecryptFile(lpFilename: PChar; dwReserved: DWORD): BOOL; stdcall;
external advapi32 name 'DecryptFileA';


procedure TForm1.Button1Click(Sender: TObject);
begin
if not EncryptFile('c:\temp') then
ShowMessage('Cant encrypt directory.');
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
if not DecryptFile('c:\temp', 0) then
ShowMessage('Cant decrypt directory.');
end;