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How You Can Password-Protect Your PDF Files

Portable Document Format (PDF) files have become the standard for sharing documents digitally. PDFs can contain text, images, multimedia elements, and advanced features like form fields and interactivity. Crucially, PDFs preserve the formatting and layout of a document regardless of the software, device or operating system used to view the file. This makes it easy to share PDFs widely across platforms.

However, the same broad compatibility that makes PDFs so useful also presents security risks if sensitive information is included in the documents. Unlike a physical paper document, digital PDF files can be easily copied, modified, forwarded and distributed without the owner‘s knowledge or permission.

Fortunately, password-protecting PDFs is an effective way to restrict access and maintain control over these ubiquitous document files. Let‘s look at why you may want to secure your PDFs, how password protection works, and step-by-step instructions for adding PDF security on Windows, Mac, Android and iOS devices.

Why Password Protect Your PDFs?

There are many good reasons to consider adding password protection when creating and sharing PDF files:

  • Prevent unauthorized access – Requiring a password prevents unknown recipients from accessing and viewing the contents of a PDF without permission. According to HP research, 61% of office workers share potentially sensitive documents. Password protection reduces accidental data leakage.
  • Protect confidential data – PDFs can include confidential personal, financial, medical or company data that should not be exposed externally. For example, human resources departments often password protect sensitive employee records shared digitally as PDFs.
  • Limit recipient actions – PDF passwords can restrict actions like editing, printing and copying content in addition to just viewing. For example, you can allow access to read a PDF book or manual but prevent unauthorized printing and sharing of the contents.
  • Control distribution – By only communicating the PDF password to designated recipients, you maintain tight control over who can actually access and view the contents. This selective sharing helps prevent misuse.
  • Expiring access – Some PDF editors allow setting an expiration date or timeframe after which the password will no longer grant access to the protected document. This is useful for time-limited sharing.
  • Track activity – Advanced PDF software enables tracking statistics showing how often a password-protected document was accessed, by whom, when and what they did. This auditing capability increases accountability.

According to an Adobe survey, over one-third of professionals share sensitive documents regularly. Password protection offers an easy way to secure PDFs containing data that should not be exposed outside your organization.

How PDF Password Protection Works

In simple terms, password-protecting a PDF involves creating a document open password that users must supply to view the contents:

How PDF password protection works

More specifically, when you apply password protection in PDF editing software such as Adobe Acrobat:

  • A cryptographic hash value representing the password is calculated and stored in the PDF metadata. This hash uses algorithms like SHA-256 to convert variable length passwords into fixed length values.
  • A user access key is derived from the password hash and used to encrypt the PDF document contents. This access key scrambles the contents to make them unreadable.
  • To view the PDF, the password is hashed again and used to generate the access key that decrypts the contents so they can be displayed.
  • Entering an incorrect password will fail to generate the correct access key so the contents remain scrambled.

In addition to the document open password, a permissions password can be set to selectively restrict actions like printing and editing even if users supply the main password. Overall, PDF password protection aims to maintain document integrity and confidentiality.

Setting PDF Passwords

Now let‘s go through the steps required to set PDF passwords on each major platform – Windows, Mac, Android and iOS:

Password Protect PDF on Windows

There are several good options for adding password protection to PDFs on Windows PCs:

Using Adobe Acrobat Reader

Adobe Acrobat Reader is free and enables basic PDF password protection:

  1. Open the PDF file in Acrobat Reader.
  2. Select Protect -> Add Security in the toolbar ribbon.
  3. Create a Document Open password and confirm it. Can also set permissions.
  4. Click Apply to save the password protected PDF.

Using Microsoft Print to PDF Function

No special software needed. The built-in Windows Print to PDF function includes password protection:

  1. Open the PDF file in any application then select Microsoft Print to PDF as the printer.
  2. Check the box for requiring a password to open the document.
  3. Type and confirm the password then save the PDF.

Using PDF Password Protect Tool

Adobe provides a handy online PDF password tool. Simply upload a PDF to apply password protection:

  1. Upload the PDF file.
  2. Enter and confirm the desired password.
  3. Click Set Password and download protected PDF.

So in summary, securing PDFs with passwords on Windows is straightforward using either Adobe‘s free software or built-in OS tools.

Password Protect PDF on Mac

Mac users also have a couple options for applying PDF password security:

Using Preview App

The Preview app included on all Macs provides basic PDF encryption:

  1. Open the PDF in Preview.
  2. Go to File -> Export as PDF.
  3. Enable password protection and create a password.
  4. Export and save the protected PDF.

Using Adobe Acrobat Reader

The process is the same as on Windows – open the PDF in Acrobat Reader, go to Protect -> Add Security to set the password.

So Mac users don‘t need any paid software to password protect PDFs securely thanks to built-in Preview capabilities.

Password Protect PDF on Android

There are many great PDF apps for Android that support password protection:

Using Adobe Acrobat Reader

Adobe‘s free Android app enables password protecting PDFs:

  1. Open the PDF in Acrobat Reader.
  2. Tap the Protect icon in the top toolbar.
  3. Configure password settings and create a password.
  4. Tap Apply to save the protected PDF.

Using Foxit PDF Reader

Foxit is a popular free alternative for working with PDFs on Android.

  1. Tap the hamburger menu and select Protect.
  2. Choose password restrictions and create a password.
  3. Tap OK to apply protection.

Using Google Drive

You can also password protect PDFs stored in Google Drive:

  1. Open the PDF and select the 3-dot menu.
  2. Tap Get shareable link.
  3. Enable link restrictions and create a password.
  4. Tap Apply to generate the protected link.

So Android users have excellent options for securing PDF files using apps likely already installed on their device.

Password Protect PDF on iOS

Apple‘s iOS also makes it simple to add password protection to PDFs:

Using Adobe Acrobat Reader

As with other platforms, Adobe‘s free Reader app enables passwords on iOS:

  1. Open the PDF in Acrobat Reader.
  2. Tap the Protect icon in the top toolbar.
  3. Configure protection settings and create a password.
  4. Tap Apply to save the secured PDF.

Using Safari

Apple‘s Safari browser can also password protect PDFs:

  1. Open the PDF in Safari.
  2. Tap the Share icon and select Create PDF.
  3. Enable password protection and create a password.
  4. Save the protected PDF to Files.

Using Print to PDF Function

The native iOS Print to PDF function can also be used to copy a PDF with a password.

So iPhone and iPad users have built-in options for applying password protection to PDF files as part of the operating system.

Removing PDF Passwords

To remove password security from a protected PDF:

  • You need to open the PDF in editing software that supports passwords, like Adobe Acrobat.
  • Enter the current user or owner password when prompted.
  • Go to Protect -> Encrypt -> Remove Security.
  • Delete the current password and save the changes.

The PDF will now open without requiring a password. But remember – you must have the original password in order to be able to remove protection.

Choosing Strong PDF Passwords

To ensure maximum security, it‘s important to choose strong passwords when protecting your PDF files:

  • Use passwords that are long and complex – at least 12 characters, mixing uppercase/lowercase letters, numbers and symbols.
  • Avoid common passwords, personal information, or dictionary words that are easy to guess.
  • Don‘t reuse the same password across different PDF documents or sites. Reuse makes you vulnerable if one password is compromised.
  • Consider using a password manager like LastPass or 1Password to generate and store unique, strong passwords for all your protected PDFs.
  • Change PDF passwords periodically or whenever you need to share with new recipients. Don‘t let passwords stay static for years.
  • Always store PDF passwords securely – never write them down or email in plain text.

Taking these measures will ensure your secured PDF documents remain protected against unauthorized access even if the password is lost or stolen.

Storing and Sharing Secure PDFs

In addition to strong passwords, you should follow security best practices for transmitting and storing PDF files protected with passwords:

  • Use secure channels like encrypted email or messaging when sharing password-protected PDF links rather than plain text.
  • Limit sharing only to recipients who need access rather than distributing widely.
  • Avoid public cloud uploads that could expose encrypted PDFs – use enterprise cloud storage with access controls instead.
  • Remove passwords promptly when sharing is complete or expires.
  • Leverage digital rights management (DRM) solutions to control document usage, track activity history, and revoke access remotely.

Adopting these data security practices will minimize the risk of sensitive information within your password-protected PDFs falling into the wrong hands.


Adding password protection provides an important security layer when sharing PDF documents containing private or confidential data. Fortunately, it‘s easy to password protect PDFs using free built-in tools on Windows, Mac, Android and iOS.

Using strong passwords and following best practices ensures your secured PDFs live up to their name by keeping information private and restricting access only to authorized recipients. So don‘t hesitate to lock down your sensitive PDFs!


Streamr Go

StreamrGo is always about privacy, specifically protecting your privacy online by increasing security and better standard privacy practices.