EasyXLS

How to protect Excel file with password in C#.NET

/* -----------------------------------------------------------------------------
 * Tutorial 27
 *
 * This tutorial shows how to create an Excel file in C# and
 * encrypt the Excel file by setting the password required for opening the file.
 * ----------------------------------------------------------------------------- */
Click here to see the Excel file	

using System;
using EasyXLS;

public class Tutorial27
{
    [STAThread]
    static void Main()
    {
        Console.WriteLine("Tutorial 27\n----------\n");

        // Create an instance of the class that exports Excel files, having two sheets
        ExcelDocument workbook = new ExcelDocument(2);
  
        // Set the sheet names
        workbook.easy_getSheetAt(0).setSheetName("First tab");
        workbook.easy_getSheetAt(1).setSheetName("Second tab");

        // Set the password for protecting the Excel file when the file is open
        workbook.easy_getOptions().setPasswordToOpen("password");
  
        // Export Excel file
        Console.WriteLine("Writing file C:\\Samples\\Tutorial27.xls.");
        workbook.easy_WriteXLSFile("C:\\Samples\\Tutorial27.xls");

        // Confirm export of Excel file
        String sError = workbook.easy_getError();
        if (sError.Equals(""))
            Console.Write("\nFile successfully created. Press Enter to Exit...");
        else
            Console.Write("\nError encountered: " + sError + "\nPress Enter to Exit...");

        // Dispose memory
        workbook.Dispose();

        Console.ReadLine();
    }
}

EasyXLS Excel libraries:

.NET
Excel Library for C#
full .NET version to import, export or convert Excel files
Excel Writer for C#
.NET version to create and export Excel files
Download EasyXLS™ Excel Library for C#

File formats:

MS Excel 97 - 2003
MS Excel 2007 - 2010
MS Excel 2013
MS Excel 2016
MS Excel 2019
XLSX XLSM XLSB XLS
XML HTML CSV TXT