Protect Base64 PDF with a password using iText 7

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Posted On: 06-Sep-2019 23:10

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c#.netcore pdf base-64 itext-7

Using iText 7, we can define two passwords: a user password and an owner password. A pdf that is encrypted with an owner password can be opened by every one who receives the document. The owner password is there to define permissions (for instance: the document can be viewed, but not printed). If a pdf is encrypted using a user password, everybody who knows the user password can open the file. There is no username, only a user password.

Nuget Package:

Install-Package itext7 -Version 7.1.7

Import Following packages:

using iText.Kernel.Pdf;
using System;
using System.Text;
using System.IO;

Source Code

public static string EncryptPDFwithPassword(string pdfBase64, string passwordUser, string passwordOwner)
{
    var encryptedBase64 = string.Empty;
    var srcBytes = Convert.FromBase64String(pdfBase64);
    var userPassword = Encoding.ASCII.GetBytes(passwordUser);
    var ownerPassword = Encoding.ASCII.GetBytes(passwordOwner);

    PdfReader reader = new PdfReader(new MemoryStream(srcBytes));
    WriterProperties props = new WriterProperties()
            .SetStandardEncryption(userPassword, ownerPassword, EncryptionConstants.ALLOW_PRINTING,
                    EncryptionConstants.ENCRYPTION_AES_128 | EncryptionConstants.DO_NOT_ENCRYPT_METADATA);

    using (var memoryStream = new MemoryStream())
    {
        PdfWriter writer = new PdfWriter(memoryStream, props);
        PdfDocument pdfDoc = new PdfDocument(reader, writer);
        pdfDoc.Close();
        encryptedBase64 = Convert.ToBase64String(memoryStream.ToArray());
    }

    return encryptedBase64;
}

Use it as:

EncryptPDFwithPassword("base64pdf-without-any-prefixes", "niceuser", "niceowner");

References:

https://www.nuget.org/packages/itext7/
https://itextpdf.com/en/resources/faq/technical-support/itext-7/how-protect-pdf-username-and-password
https://itextpdf.com/en/resources/faq/technical-support/itext-7/how-protect-already-existing-pdf-password

1 Comments

Yes, you're right— iText 7 allows you to set two types of passwords for a PDF file: a user password and an owner password . These serve different purposes and are widely used for securing PDF documents programmatically.

Understanding PDF Passwords with iText 7

User Password:

* Required to open and view the PDF.
* Only users who know this password can access the content.
* There is no concept of a username , just a password.

Owner Password:

* Used to set permissions like disallowing printing, editing, or copying.
* Anyone can open the PDF, but their actions will be restricted according to the permissions set.
* The owner password is not prompted when opening the file , but needed if someone tries to change permissions or remove security.

Example: Setting User and Owner Passwords using iText 7 (C#/.NET)

Make sure you have the NuGet package installed:

```
Install-Package itext7 -Version 7.1.7
```

Here’s a sample code snippet:

```csharp
using iText.Kernel.Pdf;
using iText.Kernel.Pdf.Encryption;
using System.IO;

string src = "input.pdf";
string dest = "output_protected.pdf";

// User and Owner passwords
string userPassword = "user123";
string ownerPassword = "owner456";

PdfReader reader = new PdfReader(src);
PdfWriter writer = new PdfWriter(dest, new WriterProperties()
.SetStandardEncryption(
System.Text.Encoding.UTF8.GetBytes(userPassword),
System.Text.Encoding.UTF8.GetBytes(ownerPassword),
EncryptionConstants.ALLOW_PRINTING, // Permission example
EncryptionConstants.ENCRYPTION_AES_128));

PdfDocument pdfDoc = new PdfDocument(reader, writer);
pdfDoc.Close();
```

This code encrypts the file with both passwords and allows only printing (other actions like editing and copying will be restricted).

---

Alternative for Non-Programmers: SysTools PDF Locker

If you don’t want to write code and prefer a user-friendly, GUI-based solution, [SysTools PDF Locker](https://www.systoolsgroup.com/pdf-locker.html) is a reliable desktop tool.

Key Features:

* Add both user and owner passwords
* Restrict printing, copying, editing, and extracting pages
* Bulk lock multiple PDF files
* Fully offline – no data uploaded
* Compatible with Windows OS

SysTools PDF Locker (https://www.systoolsgroup.com/pdf/lock/) is ideal for users who need to secure PDF files without diving into development environments like iText or scripting.

---

Summary

* Use iText 7 if you're comfortable with C# and want full control programmatically.
* Use SysTools PDF Locker if you prefer a GUI-based, no-code solution for securing PDFs with password protection and permission settings.