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How to Lock A PDF File: A Quick Guide (Adobe Reader, Mac, Mobile, and More)

June 28, 2022
Author
Inkit Team

Did you know that cybercrimes went up by 600% during the COVID-19 pandemic? 

The rise of work work-from-home culture has made it easier for hackers to access confidential business information and for sensitive information to leak

If you’re regularly communicating, collaborating with co-workers, or sharing work documents over email and other channels, the least you can do is lock your PDF files.

Locking or password-protecting a PDF file is a simple and easy solution to keep your private information secure.

In fact, it’s one of the most useful data management practices if you work in an organization where information is essential in your daily operations.

As we’re about to cover below, there are many different ways you can encrypt your PDF documents and important information.

In this post, we’ll cover all the different ways you can lock your PDF documents. Whether you want to do it with Adobe Acrobat, on a Mac, remotely with your mobile device, and more.

Here’s what we’ll cover:

  • 2 Main Types Of PDF Password Locks And Secure PDFs
  • How To Lock A PDF Document From Editing (Adobe Reader, On Mac With Preview, On Mobile, Online)
  • How To Unlock A PDF Document If You Forgot Your Password
  • How To Password Protect Your Google Docs?

2 Main Types Of PDF Password Locks And Secure PDFs

There are 2 main types of password locks you can use to secure your PDF: open and permission passwords.

Here’s what’s the difference between an open and a permission password.:

PDF open password (user password)

A document open password (also known as a user password) is a password type that restricts people from opening or viewing a PDF document. 

This is the password that any PDF viewer prompts you to input when you open a certain document. 

Permissions password (owner password)

A permissions password (also known as an owner password) is a password type that sets restrictions on a PDF document’s usage. 

For instance, on printing, content copying, editing, commenting, etc. You’ll be prompted to provide this password if you try to make any changes to a certain document. It is an extra level of protection on top of the PDF open password.  

How To Lock A PDF Document From Editing (Adobe Reader, On Mac With Preview, On Mobile, Online)

You can lock a PDF from editing by putting an owner password on it. 

There are multiple ways in which you can achieve this. Some of the major ways to lock a PDF from editing include doing so with Adobe Reader, Preview, a free online PDF tool, and more.

Below, we’ll cover each method for locking a PDF from editing.

How to password protect a PDF document in Adobe Reader

In order to password protect your PDF in Adobe reader, you’ll require the paid version, i.e., the Adobe Acrobat Pro DC. 

Once you have it, follow the following steps to password protect your PDF from editing:

Step 1: Open the PDF Document

Open the PDF document in Adobe Acrobat Pro DC. If it’s set as your default PDF viewer, then your document will open automatically in it. 

If not, then open Adobe Acrobat, go to ‘File’, click on ‘Open’, navigate to the PDF that you want to password protect, and click ‘Open’.

how to open a file

Step 2: Open the Protect Tool

Once the file is open, go to the ‘Tools’ section, and find the ‘Protect’ option. Click on it. 

protect tool option

Step 3: Create User and Owner Password

In the ‘Protect’ tool, click on ‘Encrypt’. A dropdown will appear, choose ’Encrypt with Password’.

encrypt your document with a password

Tick the ‘Require a password to open the document’ option, and enter a strong password next to ‘Document Open Password’. 

Now, tick ‘Restrict editing and printing of the document’. 

A password will be required in order to change these permission settings, and enter a password next to ‘Change Permission Password’. You can play around with the permissions by clicking the dropdown next to ‘Printing Allowed’ and ‘Changes Allowed’. 

change to the security settings

Step 4: Confirm Passwords

You will be prompted to confirm the Document Open Password. Click ‘Ok’ to confirm the document open password.

enter password

Step 5: Save the PDF

Your password setting won’t be saved unless you save the document. A new window will pop up to remind you of this, click on ‘Ok’, and then press Ctrl + S to save the document.

security alert

Looking for more ways to edit, manage, or manipulate your PDF documents with or without Adobe Acrobat?

Be sure to also read:

How to lock a PDF file on Mac with Preview

You can password-protect a PDF in Mac without requiring any external software. The Mac’s built-in PDF viewer, Preview, allows you to set both owner and user passwords. Here’s how:

Step 1: Open PDF in Preview

Head over to the PDF file that you want to password-protect. Double click on the file to open it in Preview. If Preview isn’t the default app, then right-click on the file name, select ‘Open With’, and select ‘Preview’.

opening a document on a mac

Step 2: Export the PDF

Once the PDF file is open in Preview, click on ‘File’, and select ‘Export’. You can either update the current PDF file or you can save it as a different file through this option. 

export file as... option

Step 3: Create Password

Click ‘Permissions...’, which is at the bottom of the Export window.

change the permission of your document

Tick the ‘Require Password To Open Document’ box, type a password, and verify it in the next tab. Select whichever permissions you require. Now, input a password in the Owner Password, and verify it by re-typing it. 

ask to require a password when opening your document

Click ‘Apply’ and then ‘Save’ to save the new password setting. 

Wondering what are some other edits you can do to PDF documents on Mac with Preview?

Also read:

Out-of-the-box PDF generation
The easiest way to automatically generate and manage paperless documents at scale.
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How to lock a PDF file on mobile

You can lock a PDF on your Android or iPhone by using the Kdan PDF Reader app. Here’s how:

Step 1: Download a PDF Reader app for your phone

Most PDF apps from the app store will do the job if you want to lock a PDF document remotely from your mobile.

Download one whether you’re an iPhone or Android user.

Step 2: Encrypt the PDF
Open the PDF in the PDF Reader, and then tap on three vertical dots on the top right of the screen.

pdf mobile settings

A new menu will open, select ‘Encrypt’ from it. 

encrypt settings on mobile

Enter a password in the Password section on the new pop-up and click ‘Ok’. 

set a password to encrypt your pdf

The password-protected PDF file will be saved in a new folder ‘Encrypt & Decrypt’ in your files section. 

encrypt & decrypt files

For more ways to edit or manipulate your PDF documents remotely on mobile, also check out:

How to lock a PDF document online

We usually don’t recommend using online tools for PDFs containing confidential data. But if you are in a pinch, then most free, online PDF tools will get the job done.

For this example, we’ll be using Smallpdf. Though, regardless of the online tool you use, the steps will be similar, if not the same.

Essentially, you’ll be uploading your PDF document to a web-page and locking it online.

Step 1: Upload the PDF file

Click on ‘Choose File’ to upload your PDF file. A new window will open, navigate to the file that you want to password-protect, and click ‘Open’. 

choose a pdf to lock

Step 3: Encrypt the PDF File

Enter a password in the ‘Choose Your Password’ bar. Retype the password to verify it in the ‘Repeat Your Password’ tab. 

repeat your password and make sure it's something you'll remember

After entering passwords, the ‘Encrypt Your File’ option will become visible. Click on it to encrypt your file.

encrypt your file

How To Unlock A PDF Document If You Forgot Your Password

What if you locked your PDF file and forgot your password?

If you’ve forgotten the password to your document, then there are multiple ways to unlock it. 

Probably the easiest option is to use an online tool. Though, once again, it’s not recommended to do so if you’re dealing with confidential, sensitive data.

Here’s how you can unlock a PDF document online:

  1. Open the Smallpdf’s online PDF password remover tool.
  2. Click on ‘Choose File’ to upload the password-protected PDF. A new window will open, navigate to the required PDF file, and click ‘Open’. 
select a file to unlock
  1. The Smallpdf’s password removal tool will ask you to pinky promise that it’s your PDF document. Do it by clicking on the check box.
security banner for unlocking a document
  1. The ‘Unlock PDF’ button will become visible, click on it to unlock the PDF. 
confirm you want to unlock your pdf
  1. Click on ‘Download’ to download the new unprotected PDF file. You can export and share the document as well. 
download the now unlocked file

Unfortunately, removing password protection through an online source isn’t the safest option. 

So, if you’re looking for more ways to unlock your PDF document if you’ve forgotten your password, be sure to also read:

How To Password Protect Your Google Docs?

There are numerous ways to password protect your documents on Google Docs. 

Though, the easiest option is to password protect it using MS Word and then upload it to Google Docs. 

Here’s how to password protect your Google Docs file:

  1. Open the word document that you want to protect in MS Word. You can use this trick to protect PDFs as well by converting them to a word document. 
  2. Once the document is open, click on ‘File’, and then ‘Info’. Click on ‘Protect Document’, and then select ‘Encrypt with Password’ from the drop-down.
password protect your files in MW
  1. The following window will open. Select a strong password and remember it as you won’t be able to recover the document if you forget it. 
create a password to encrypt your file
  1. Upload the password-protected document to Google Docs.

Looking for more ways to password protect and lock your Google Docs?

Be sure to also see:

Conclusion

We hope that by now you have learned how to password protect your PDF documents! 

Remember, leaving your confidential documents unprotected in today’s world of cyber security threats isn’t wise, and thus, you shouldn’t skim on their security. 

Now, for more information on getting the most out of your PDF files and documents, be sure to also read:

Out-of-the-box PDF generation
The easiest way to automatically generate and manage paperless documents at scale.
By submitting this form, I confirm that I have read and understood Inkit's Privacy Policy.
Oops! Something went wrong while submitting the form.