How to Sign a Secured PDF File [Locked & Protected Signing]

Written By Kumar Raj
Anuraag Singh
Approved By Anuraag Singh  
Published On April 4th, 2024
Reading Time 6 Minutes Reading

It may seem a little tricky to sign a secured PDF document, but fear not! In this guide, we’ll walk you through the simple steps to sign a locked PDF. Whether it’s password protected or not, users will be able to put a digital signature on it.

Table of Contents

Important Points to Know Before You Start

Before we dive into signing secured PDF files, here are a few important points to remember:

  • There are two password types: Open-Password and Permission-password.
  • Open-password restricts access to the PDF document i.e., you cannot open the PDF without the password.
  • Permission password adds restrictions to the PDF document i.e., you cannot perform certain tasks like edit, print, etc.
  • To sign a PDF that has open-password, you MUST know the password.
  • To sign a PDF that has permission-password depends on the method used. There are solutions whether you remember the password or not.
  • To sign a secured PDF, you’ll typically need a PDF editor with signing capabilities.

The Tools You’ll Need

If the PDF file has open-password then you have two methods:

  • Adobe Acrobat Pro DC (password required)
  • Professional Tool (password required)

If the PDF file has permission-password then you have two methods:

  • Adobe Acrobat Pro DC (password required)
  • Professional Tool (no password required)

How to Sign a Secured PDF using Adobe Acrobat (Password Required)

The premium version of Adobe Acrobat provides the option to sign a protected PDF. Do note that this method won’t work with Adobe Reader; you’ll need to subscribe to Adobe Acrobat Pro DC to get the relevant options.

For Open-Password

Here’s a step-by-step guide on signing a secured PDF using Adobe Acrobat:

  1. Firstly, open the password protected PDF document in Adobe Acrobat.
  2. If it has open-password, Adobe will ask for it; enter the password to proceed. If not, skip to the next step.
  3. Look for the Fill & Sign option, usually found in the right-hand pane.
  4. Then, click on Fill & Sign, then select Sign from the toolbar that appears at the top.
  5. After that, choose Add Signature.
  6. If you’ve already created a digital signature, select Use a signature I have created. If not, you can choose to create a new signature.
  7. Now, follow the on-screen instructions to create or insert your signature.
  8. Once your signature is ready, click to place it in the appropriate location within the PDF.
  9. Then, you can resize or reposition your signature as needed.
  10. Finally, save the PDF with your digital signature.

For Permission-Password

If the sign feature is greyed out/disabled, then that means the PDF has a permission-password and sign is restricted in it. So, first we need to remove restrictions from PDF. To do this, follow these steps:

  1. Open the file in Adobe.
  2. Click on the Protect option in Tools.
  3. Choose Advanced Options and select Remove security.
  4. Type the permission password and click OK.
  5. Save the PDF file to apply the changes.
  6. Now, you can sign the PDF without any hindrance.

How to Sign a Locked PDF with Professional Tool (No Password)

SysTools PDF Password Remover is the easiest and fastest way to enable signing in secured PDF files. It can batch process multiple PDF files without any hassle. So, users can unlock PDF for signing in bulk.

Please note that the tool itself does not provide options to sign the PDF file. However, it removes the signing restriction and password from it. By doing this, you can easily use any PDF editor (including Adobe) to sign the PDF file.

Here’s a general outline of the process:

  • Open the software on your system. It supports both Windows & Mac.
  • Once done, use Add Files button to add all the locked PDF files that you want to sign.
    add pdf
  • If the file has open-password, enter it. If not, skip to the next step.
    enter password
  • After that, click the Unlock button and the software will bypass permissions password and directly unlock signing option in the PDF documents.
    how to sign a locked pdf
  • Now you can use Adobe or any other PDF editor to sign the document.

Tips for Signing Secured PDF Files

Here are some additional tips to keep in mind:

  • While Adobe Acrobat Reader is a popular choice, other PDF readers or editors may also offer signing capabilities.
  • Always check the security settings of the PDF to ensure you have the necessary permissions to add a signature.
  • If you’re asked to create a digital signature, you can often choose between drawing your signature, using a stylus, or typing your name in a signature font.
  • Make sure your digital signature is legible and looks professional.
  • Double-check the placement of your signature within the document to ensure it aligns with any designated signature fields.


When it comes to signing a secured PDF, what type of password makes it secure is important. After all, if has open-password, then you must enter it and sign the PDF file in any PDF reader or editor. But if it has permission-password, then remembering it is unnecessary. You can simply use the professional tool to remove the secured status from PDF file. Then, add signature to locked or protected PDF documents.


Q) Can I sign a secured PDF without the necessary permissions?

No, you generally cannot sign a secured PDF without the required permissions. You must first remove it by using the relevant password or bypass it using a software.

Q) Can I sign a locked PDF on a mobile device or tablet?

Yes, you can sign a protected PDF on a mobile device or tablet using PDF reader apps that offer signing capabilities. The process is similar to signing on a computer.

Q) Is there a difference between a locked PDF and a protected PDF?

In the context of signing, both terms usually refer to the same action.


By Kumar Raj

Kumar Raj has more than 14 plus years of expertise in migration technology. He likes to create, edit, and optimize web material on topics conversion of email data, and migration of email data. For the majority of the past ten years, he has been a devoted fan of the technology scene.