How to Set PDF Passwords and Permissions in C#

What's the Difference Between User and Owner Passwords?

The User Password (also known as the open password) is required to open and view the PDF document. Without this password, the PDF cannot be accessed at all. In contrast, the Owner Password (or permissions password) grants full control over the document's security settings. When you open a PDF with the owner password, you can modify permissions, remove passwords, and have unrestricted access to all document features. This dual-password system provides flexible security options for different use cases, from simple document protection to complex permission management scenarios.

Why Should I Use Both Password Types?

Using both password types creates a comprehensive security strategy. The user password ensures only authorized individuals can view the document, while the owner password provides administrative control. This is particularly useful in business environments where you might want employees to view documents (using the user password) but only managers to modify permissions or remove protection (using the owner password). Additionally, this approach aligns with compliance requirements in many industries that mandate different access levels for sensitive documents.

What Happens When Users Enter Each Password?

When users enter the user password, they gain read access to the document based on the permissions you've set. They can view the content but may be restricted from printing, copying text, or making modifications. When the owner password is entered, all restrictions are lifted, and the user gains full administrative privileges over the document, including the ability to change passwords and modify permission settings.

We have an example PDF file that we want to protect using IronPDF. Let's execute the following code to add a password to the PDF. In this example, we will use the password password123. This approach works seamlessly whether you're creating PDFs from HTML or working with existing documents.

:path=/static-assets/pdf/content-code-examples/how-to/pdf-permissions-passwords-add-password.cs

using IronPdf;

ChromePdfRenderer renderer = new ChromePdfRenderer();

PdfDocument pdf = renderer.RenderHtmlAsPdf("<h1>Secret Information:</h1> Hello World");

// Password to edit the pdf
pdf.SecuritySettings.OwnerPassword = "123password";

// Password to open the pdf
pdf.SecuritySettings.UserPassword = "password123";

pdf.SaveAs("protected.pdf");

The result is the following PDF which you can view by typing the password password123.

What Parameters Does FromFile Accept?

The PdfDocument.FromFile method accepts two main parameters: the file path and an optional password string. When working with password-protected PDFs, you must provide the correct password as the second parameter. The method automatically detects whether the provided password is a user or owner password and grants appropriate access levels. This seamless integration makes it easy to work with protected documents in your C# applications.

How Do I Handle Incorrect Password Attempts?

When an incorrect password is provided, IronPDF throws a specific exception that you can catch and handle appropriately. Best practice involves implementing a try-catch block to manage password failures gracefully:

try 
{
    var pdf = PdfDocument.FromFile("protected.pdf", userPassword);
    // Process the PDF
}
catch (IronPdf.Exceptions.IronPdfPasswordException ex)
{
    // Handle incorrect password
    Console.WriteLine("Invalid password provided");
}

try 
{
    var pdf = PdfDocument.FromFile("protected.pdf", userPassword);
    // Process the PDF
}
catch (IronPdf.Exceptions.IronPdfPasswordException ex)
{
    // Handle incorrect password
    Console.WriteLine("Invalid password provided");
}

Can I Remove Password Protection After Opening?

Yes, once you've opened a PDF with the owner password, you can remove all password protection using the RemovePasswordsAndEncryption() method. This is useful when you need to distribute previously protected documents or integrate them into systems that don't support password-protected PDFs.

This section describes how to open a PDF that has a password. The PdfDocument.FromFile method has a second optional parameter which is the password. Provide the correct password to this parameter to open the PDF. This functionality integrates well with other IronPDF features like merging PDFs and extracting text.

:path=/static-assets/pdf/content-code-examples/how-to/pdf-permissions-passwords-open-password.cs

using IronPdf;

var pdf = PdfDocument.FromFile("protected.pdf", "password123");

//... perform PDF-tasks

pdf.SaveAs("protected_2.pdf"); // Saved as another file

Which Permissions Can I Control?

IronPDF provides granular control over PDF permissions through its SecuritySettings class. You can manage various permissions including:

• AllowUserAnnotations: Controls whether users can add comments and annotations
• AllowUserCopyPasteContent: Restricts text and image copying
• AllowUserFormData: Manages form filling capabilities
• AllowUserPrinting: Sets printing permissions with options for high-quality or low-resolution printing
• AllowUserEditing: Controls document modification rights

These permissions work in conjunction with password protection to create comprehensive security policies that match your specific requirements.

How Do Permissions Interact with Passwords?

Permission settings behave differently based on the password configuration. When no password is set, permissions are enforced but can potentially be bypassed by PDF editing software. With only a user password, entering it grants access according to the defined permissions. However, when both passwords are set, the user password provides restricted access while the owner password overrides all permissions, granting full control. This hierarchical system ensures proper access control for different user roles.

What Metadata Fields Can I Set?

The PdfDocument object also has metadata fields you may set such as Author and ModifiedDate. Additional metadata properties include Title, Subject, Keywords, Creator, and Producer. These fields are essential for document management systems and compliance requirements. You can set custom metadata fields as well, which is particularly useful for internal tracking and categorization. Learn more about metadata management in our detailed guide.

When Should I Use MakePdfDocumentReadOnly?

The MakePdfDocumentReadOnly method is ideal when you need to create a final, uneditable version of a document while maintaining some level of access control. This method combines password protection with restrictive permissions in a single call, making it perfect for archival purposes, legal documents, or final reports that should remain unchanged. It's particularly useful in document workflows where you need to ensure document integrity.

You can also disable user annotations, user printing, and many more as shown below:

:path=/static-assets/pdf/content-code-examples/how-to/pdf-permissions-passwords-advanced.cs

using IronPdf;

// Open an Encrypted File, alternatively create a new PDF from HTML
var pdf = PdfDocument.FromFile("protected.pdf", "password123");

// Edit file security settings
// The following code makes a PDF read only and will disallow copy & paste and printing
pdf.SecuritySettings.RemovePasswordsAndEncryption();
pdf.SecuritySettings.MakePdfDocumentReadOnly("secret-key");
pdf.SecuritySettings.AllowUserAnnotations = false;
pdf.SecuritySettings.AllowUserCopyPasteContent = false;
pdf.SecuritySettings.AllowUserFormData = false;
pdf.SecuritySettings.AllowUserPrinting = IronPdf.Security.PdfPrintSecurity.FullPrintRights;

// Save the secure PDF
pdf.SaveAs("secured.pdf");

The permissions setting is related to the document password and behaves as follows. For example, setting the AllowUserCopyPasteContent property to false is intended to prevent copy/paste of content:

• No password set: Without a password, copy/paste of content remains blocked.
• User password set: When a user password is set, entering the correct password will allow copy/paste of content.
• Owner password set: When an owner password is set, entering only the user password will not unlock the copy/paste feature. However, entering the correct owner password will allow copy/paste of content.

A closely related article discusses predefined and custom metadata. Learn more by following this link: "How to Set and Edit PDF Metadata."

Ready to see what else you can do? Check out our tutorial page here: Sign and Secure PDFs

For enterprise applications requiring advanced security features, consider exploring PDF/A compliance for long-term document preservation or implementing digital signatures with HSM for enhanced authentication. IronPDF's security features integrate seamlessly with Azure deployment scenarios and support various rendering options to meet your specific requirements.