How to Protect Excel Files Using C#

Protect Excel Files in C# Using Aspose.Cells

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.