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How To Sign A Secured PDF: Grasping Protected PDFs & Security Tiers

Are you facing issues in signing your PDF documents? Where e-signing is a utility offered to users, there is a possibility that the PDF has a permission password associated with it. This might restrict it from being signed and edited by other users. PDFs are an important format, and securing them through passwords is a common act.

All essential yet confidential documents are available in PDFs. Meanwhile, you can also secure your PDF and even sign it. But how to sign a protected PDF in an ideal case? In this article, you'll find ways to sign the protected PDF through UPDF. First of all, download it on your computer and follow the instructions of Part 1.

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Part 1: How to Sign a Secured PDF with UPDF

When it comes to PDF editing and managing, UPDF takes the lead over all its competitors. After all, with UPDF, you can edit PDF documents, convert them into different formats, combine multiple files in a single PDF, or even organize them together. You can also apply OCR to turn your scanned PDFs and paper documents into searchable and editable PDFs.

UPDF also allows you to make a PDF signable, secure PDFs with password protection and even allows adding electronic signatures to improve a document's validity. So, if you want to know how to sign password protected PDF via UPDF, find easy and simple steps here:

Step 1: Open the Password Protected Document

Install and launch the UPDF application on your computer. Press the "Open File" button from the home screen, after which select and open the password-protected PDF.

open file how to sign a secured pdf

Step 2: Remove the Document Security

After opening your document, click the "Protect Using Password" icon from the toolbar on the right side. Continue to choose the "Remove Security" option from the "Encrypt with Password" side menu and click "Remove" from the prompt. Continue to save the password-removed file in the desired folder by clicking "Save" and setting the location.  

how to sign a locked pdf

Step 3: Add the Signature to the PDF

Add a Handwritten Signature to PDF

The password-removed file will automatically get opened. Proceed forward by clicking the "Comment" icon from the toolbar on the left side. From the tools bar in the screen's top middle side, select the "Signature" tool and press "Create." The "Create Signature" panel will open where you need to create a signature, and press "Create" again. Place the created signature on the desired area of the document and save it.

how to sign a protected pdf

Add a Digital Signature to PDF

Once you have removed the password and opened the file, go to the "Prepare Form" section by clicking the relevant icon on the left panel. Choose the "Digital Signature" icon from the top toolbar and click on your desired place on the document to add a field for the digital signature. 

Once added, go to the "Preview" mode by clicking on the Preview icon on the top toolbar and click on it to access the Sign Window. Now, you have two options: either create your digital ID by hitting the Create icon and adding your personal information or import one from your device. In case of importing, you will need to enter a password to authenticate your identity. Once you are done with all this, click on the "Sign" button to finally add a digital signature to your PDF. 

sign a secured pdf with digital siganture

Amazing, right? Give UPDF a try and solve the problem of signing a secured PDF now! Even better news is that if you upgrade UPDF now, you will get the best price of the year! Don't miss it!

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Part 2: Knowledge: What is a Secured PDF?

The secured PDF is also known as a protected PDF that is encrypted with dedicated password support. Hence, when you share the secured PDF with someone, they will require the respective password to open and access the file. Thus, it restricts all unauthorized access to your confidential information and data through a secured PDF.

Secured PDFs can help make your documents more authentic because they are protected with password protection. Thus, without the passwords, none can even edit the document.

Part 3: PDF Security Levels

PDF files are widely used for sharing and distributing electronic documents. This is because PDFs help preserve a document's original formatting and layout. In general, there exist different security levels in a PDF document:

1. Password Protection

This involves setting a user password to restrict access to the PDF document. Thus, a particular PDF cannot be accessed without the user's password. The password is set by the owner himself, who controls permission for actions like copying, editing, and printing PDFs. So, if you want to preview protected documents and access functions, you'll need a password.

In addition, password protection is divided into open and permission password features. With the open password feature, you need to enter the password to preview a password-protected document. In the case of the permission password feature, you need to enter a password before editing the password-protected document.

2. Watermarks

Watermarks are added to PDF files for copyright protection purposes. The watermarks are basically visual elements comprised of text, patterns, shapes, or even logos. Adding watermarks to your PDF documents automatically extends the layer of security. It's because watermarks can't be removed, and they prevent copyright infringement issues.

3. Encryption

Adding encryption is ideal for extending the security layer of PDF files. After all, encryption can help protect PDF content from unauthorized access. There exist different encryption algorithms, including AES (Advanced Encryption Standard). The encryption key lengths include 128-bit or 256-bit. This way, your PDF documents become fully secure.

4. Digital Signatures

Adding digital signatures or e-signatures to PDF documents is amongst the top PDF security layers. This is because digital signatures can help increase the authenticity and integrity of the document. They ensure the file has not been tampered with since the signature was applied. With signatures, your document becomes fully protected.

Part 4: FAQs on Signing Password Protected PDF

1. Why can't I sign a protected PDF?

If you cannot sign a protected PDF, it is likely because there might be no signing permission. Or there might be document encryption applied, or the document may have certificate-based security.

2. What is the best tool to sign a secured PDF?

Although you can find several online or offline tools for signing a secured PDF, the better and more reliable option is the UPDF PDF Editor. The reason behind recommending this tool is that it is pretty fast and provides numerous features at a cost-friendly price.

3. How do I sign a protected PDF in Foxit?

Foxit PDF Editor is also one of the reliable PDF tools for editing PDF documents. In general, you can also sign a protected PDF in Foxit. For this, follow the simple steps here:

  • Step 1: Launch the Foxit Reader or Editor on your system and access the password-protected PDF. Afterward, locate and access the "Fill & Sign" tab and tap the "+" icon to create your signature.
  • Step 2: In the Create Signature dialogue box, choose the type and create your signature. Following this, press the "OK" button and place the signature on the document wherever you want.

4. How do I sign a protected PDF in Adobe Acrobat?

To sign a protected PDF in Adobe Acrobat, follow these straightforward instructions guided here:

  • Step 1: Open the password-protected file on Adobe Acrobat and access the "Fill & Sign" from the left panel. This will open all the available sign tools of Adobe Acrobat.
  • Step 2: Following this, choose the required option, such as "Add Signature," and add your signature in the provided space. To complete the process, press the "Apply" button and adjust the signature size.


PDF documents are used in every industry that we encounter in our daily lives. Therefore, they incorporate valuable and essential information that is mostly confidential. In response, the PDF documents are primarily secured and signed to add validity to the content.

This article provided details on how to electronically sign a secured PDF. You also learned about UPDF, which is the trusted partner for all your PDF editing and managing tasks. Try it yourself and you will be impressed by its features! If you are still not sure, read the UPDF review on one of the best tech sites - howtogeek! You will see how trustful UPDF is!

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