How to Protect PowerPoint files in C#

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In this article we are going to look into a free and useful .NET PowerPoint component.


We develop applications for education organizations and in one project PowerPoint files could not be edited or reviewed by others and found a PowerPoint library. The description of the library says it is free and it can protect the PowerPoint files with password in C#.Results turn out to be great and it is quite easy to use.


Free Spire.Presentation is a PowerPoint library designed for .NET developers to operate PowerPoint documents from .NET Platform and it is standalone and not need to install Microsoft PowerPoint on the machine.

How to get it:

First download and install it correctly on your machine. The Spire.Presentation installation is clean, professional and wrapped up in a MSI installer. It does not take much space (only 58 MB) for installation.


The MSI option provides a full experience, including:

  1. Installs the assemblies (multiple assemblies to support different versions of the .NET Framework)
  2. Installs the demo projects with source code
  3. Installs the documentation locally on the developer’s machine
  4. Adds the assembly to the Add Reference dialog box in Visual Studio

After the installation, developers need to add Spire.Presentation.dll manually as reference in the Bin folder though the below path:

 “…\Spire.Presentation\Bin\NET4.0\Spire. Presentation.dll”.

Using the Code

Add this line of code on the top to start to use the Spire.Presentation.

using Spire.Presentation;

First you need to create a new presentation document and load from file

Presentation presentation = new Presentation();


It only needs one single line of code to protect your document.

Encrypt the document:


Set the document to be read only:


At last, just save the document.

presentation.SaveToFile("result.pptx", FileFormat.Pptx2007);

Check the result here:

Encrypt the file:

Read Only:


Full codes:

namespace Protect_PowerPoint
    class Program
        static void Main(string[] args)
            Presentation presentation = new Presentation();
            presentation.SaveToFile("encrypt.pptx", FileFormat.Pptx2007);
            presentation = new Presentation();
            presentation.SaveToFile("readonly.pptx", FileFormat.Pptx2007);


Supported File Formats

Spire.Presentation supports different version of Microsoft PowerPoint, such as PPT, PPS, PPTX and PPSX.

There are many other elements that this library supports:

  • Insert all kinds of shapes (such as triangle, rectangle, BackOrPreviousButton );
  • Insert audio, video;
  • Add table, chart, hyperlinks;
  • Convert to other file format, such as PDF and Image;
  • Animation.

The free version and limits:

The free version is totally free and is limited to 10 presentation slides. If your document is exceeding this limitation, you need to use the commercial version of Spire.presentation.


Overall, I was impressed by the power and ease provided by this product. You are welcome to test the demo code. And I hope this article can help. 


You can download from here.

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About the Author

Full Name: Victoria Smith
Member Level: Starter
Member Status: Member
Member Since: 7/3/2014 4:22:45 AM
Country: United States

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