Can we protect excel workbook with Password using open XML SDK?

Question

I want to password protect the excel using C#. One approach is using interop libraries, but issue with this is we need to install MS office on our Server which is not allowed in organization. What is the other approach to password protect excel using C#?

Answer 1

Hi mamtachoudhary-6642,
You could not protect an Excel file with openxml.
Using password protection doesn't not generate an Office Open XML file and you will get a file in binary file format.
The Open XML SDK does not work with the binary file formats.
One suggestion is that you use Workbook.Password property to set the password:
Here are some similar threads you can refer to.
How to protect document with password using C# and openxml
Protecting Excel file created through OpenXML
Best Regards,
Daniel Zhang

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Answer 2

Alternatively, you may use Spire.XLS for .NET for encryption or decryption of your Excel workbooks. It is a tiny .NET Excel library and does not require MS Excel to be installed on server or end users' machines. Below is the code example for your reference.

using Spire.Xls;

namespace ProtectExcel
{
    class Program
    {
        static void Main(string[] args)
        {
            //Load Workbook
            Workbook book = new Workbook();
            book.LoadFromFile(@"E:\Documents\VendorInfo.xlsx");
            //Protect Workbook
            book.Protect("abc-123");
            //Save to file
            book.SaveToFile("ProtectExcel.xlsx", ExcelVersion.Version2013);
        }
    }
}