Spreadsheet Locker
How to Protect Excel Files Using C#

How to Protect Excel Files Using C#

Protecting Excel files helps prevent unauthorized edits and ensures the integrity of critical spreadsheet data. In this article, you’ll learn how to use Aspose.Cells for .NET to apply workbook-level protection using C#.

Why Protect Excel Files?

  • Prevent accidental edits or overwrites
  • Secure sensitive information
  • Enable collaborative access with specific permissions

Step-by-Step Implementation Guide

Step 1: Create a New C# Project 

dotnet new console -n ExcelProtectionApp  
cd ExcelProtectionApp

Step 2: Install Aspose.Cells for .NET 

dotnet add package Aspose.Cells

Step 3: Load the Excel File 

Workbook workbook = new Workbook("Input.xlsx");

Step 4: Apply Protection 

workbook.Protect(ProtectionType.All, "secure123");

You can choose from:

  • ProtectionType.All
  • ProtectionType.Contents
  • ProtectionType.Objects
  • ProtectionType.Structure

Step 5: Save the Protected File 

workbook.Save("Protected.xlsx");

Best Practices

  • Store passwords securely using environment variables or secret managers.
  • Use strong alphanumeric passwords.
  • Validate protection by reopening the file post-processing.
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