public static void EncryptExcelFile(string sourceExcelPath, string destinateExcelPath, string password) { Aspose.Cells.Workbook workbook = new Aspose.Cells.Workbook(sourceExcelPath); workbook.SetEncryptionOptions(Aspose.Cells.EncryptionType.XOR, 40); workbook.SetEncryptionOptions(Aspose.Cells.EncryptionType.StrongCryptographicProvider, 128); workbook.Settings.Password = password; workbook.Save(destinateExcelPath); }