procedure EncryptBMP(const BMP: TBitmap; Key: Integer);
 var
   BytesPorScan: Integer;
   w, h: integer;
   p: pByteArray;
 begin
   try
     BytesPorScan := Abs(Integer(BMP.ScanLine[1]) -
       Integer(BMP.ScanLine[0]));
   except
     raise Exception.Create('Error');
   end;
   RandSeed := Key;
   for h := 0 to BMP.Height - 1 do
   begin
     P := BMP.ScanLine[h];
     for w := 0 to BytesPorScan - 1 do
       P^[w] := P^[w] xor Random(256);
   end;
 end;
 procedure TForm1.Button1Click(Sender: TObject);
 begin
   EncryptBMP(Image1.Picture.Bitmap, 623);
   Image1.Refresh;
 end;
 { Call the function again to decrypt it }
 { Zum Entschlusseln die Funktion nochmals aufrufen }