pdf file security

PDF File Security

PDF File Security – secure PDF files to stop sharing, copying, printing

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Secure PDFs with Safeguard PDF security

How to create a secure PDF file

Securing PDF files with Safeguard is very simple.  Select your PDFs then the ‘Make Secure PDF’ menu option.

In Safeguard Secure PDF Writer, choose the PDF security controls:

  1. Stop printing, allow printing or limit the number of prints.
  2. Add dynamic watermarks to viewed and or printed pages.  Dynamic variables replace actual user and system data when they view/print the document so you only have to protect it once for all users.
  3. Make the PDF expire on a specific date, after a number of views, after a number of prints, or after a number of days from opening.
  4. Stop screen grabbing applications (even from remote connections), prevent use of Windows print screen.
  5. Track and log document views and prints.
Safeguard’s default PDF security
  • Stops users editing, copying and pasting text and images
  • Locks PDF files to specific devices so they cannot be shared
  • Revoke PDFs at any time regardless of where they reside
  • There are no passwords for users to enter, manage, or remove

Securing PDFs with Safeguard is more secure than Adobe password protection.  Once your PDF is secured with Safeguard, you’ll benefit from total PDF security regardless of where your PDF files are located.

   DID YOU KNOW?

You should NOT password protect a PDF

  1. users can share passwords and thus ‘secure’ PDFs with others
  2. passwords are easily removed with password recovery software
  3. Adobe PDF permissions (stop copy, print etc.) can be removed without using any tools
  4. once the user has the password they can unprotect the PDF and do what they like with it

“We purchased Safeguard PDF Security to secure PDF files and control access and un-authorised use. We now have greater control on who/how our material is accessed when distributed around the world, including limiting the number of prints and using expiry controls to manage subscriptions.

Safeguard PDF Security does what it says – it provides a manageable, cost effective uncomplicated way to secure PDF documents, your investment.

We would recommend Locklizard to other companies.”

PDF security & methods used to secure PDF documents

What is PDF file security?

While PDF encryption is used to protect PDF documents so they can be securely sent to others, you may need to enforce other controls over the use of your documents to prevent authorized users using documents inappropriately.  For example, you may want to stop users from copying text or printing PDFs.

So, PDF file security is delivered by a combination of different features – encryption, controls (digital rights management controls), etc. – that are relevant to the overall document controls you wish to achieve.

PDF file security can consist of the following components:

The amount of security you achieve depends on the effectiveness of the controls you implement and how the system is designed.

Underpinning the controls is the strength of the PDF encryption and the implementation method.  If it is weak or users can easily subvert it, it adds no value.

  PDF Security components

  • PDF Encryption

    Encryption is used to prevent unauthorized users from accessing your PDF files.

    • Once a user has the decryption key they can unprotect the PDF and do what they like with it unless DRM controls have also been used
    • If a PDF has been encrypted with a password, users can easily remove it with password recovery programs
    • The most commonly used secure encryption algorithm for PDF encryption is AES (US Government strength)
    • PDF copy protection is implemented through the use of PDF encryption. It is almost impossible to prevent people from copying files – after all, everything on a computer has been copied to use it.  But if a user doesn’t know the decryption key for a file, they cannot use the file regardless of whether someone has copied it or not.
  • PDF Restrictions

    PDF Restrictions give you some control over what an authorized user can do with a document.  In Adobe Acrobat they are called PDF Permissions and enable you to restrict editing, printing, or copying text.

    However they do not provide any actual security:

    There is no point in applying PDF security controls that users can readily bypass.

  • DRM controls

    DRM controls enforce what an authorized user can do with a document.  These enable you to:

    Unlike Adobe permissions these cannot be removed.

    PDF digital rights management is discussed in more detail here – PDF digital rights management.

  • PDF Password Protection

    To encrypt a PDF you need to use a key.  The most common method is using a password as the key.  However, PDF Password Protection has serious issues and is not recommended if you want to secure PDF files from unauthorized use and distribution.

    • Passwords can be shared around – they have to be sent in a readable form, so users can copy and forward them to anyone
    • The password interface has to be exposed so can be readily attacked by password recovery programs – see Removing PDF Passwords
    • Strong passwords are difficult to set up and use, so users and admin typically implement weak ones instead.
    • You have to manage a list of passwords if you use different passwords for each PDF document which can be complicated.
  • Public Key Technology or PKI

    PKI has two major uses.  It is used to:

    • protect the secret decryption key, preventing the user or attacker from finding it
    • create a digital signature which establishes that the document has not been altered and verifies the sender

    Public Key Technology is much more secure than password protection – the key is not exposed to the user so cannot be attacked.  In addition there are no passwords to manage or for users to forget.

  • Licensing controls

    Licensing controls allow you to establish policies, watermarks, and restrictions that are unique to each user.

    You can distribute a single document that has different license conditions depending on the user.  For example:

    • User A is allowed to print document A but user B is not
    • User A is allowed to view document A for 15 days but user B can view it forever
    • You can revoke any access to a specific document for an individual user(s) or all users

    Licensing controls also enable you to lock PDFs to specific devices and track document use.

  • Proprietary security mechanisms

    These are used to control Operating System specific behaviour such as:

    • preventing screen grabbing and third party screen grabbers from taking screenshots
    • stopping printing to file drivers (i.e. Adobe PDF files)
    • preventing temporary files being created that store unprotected copies of a PDF

    Additional security implementations can be used to:

    • identify unique machine information to enable locking of PDF documents to devices, IP address(es) and locations
    • store decryption keys securely and prevent them from being shared

Securing PDF files – FAQs

  What is a secured PDF file?

A secured PDF file simply refers to a PDF file that has been protected by a piece of software.

However, the security of PDF files grouped under this banner can vary wildly depending on the solution used to protect them.

  Why would I want to secure my PDF documents?

There are many reasons why you would want to secure your PDF documents using PDF file security.  The main reason, however, is that you need protection for your PDF documents beyond what encryption provides.

This is likely because you want to have some control over your PDF documents once they have been decrypted (for example, whether a recipient can copy text from your document).  This can be because the document contains privileged information or you are selling information that you do not want to be distributed for free.

  How can I secure my PDF documents?

At the basic level, you could use a product like Adobe Acrobat.  However, it is wise to remember that there are freely available Internet tools that can remove the copy controls you have applied in seconds.  This is also true of other secure PDF products that use passwords or plugins to Adobe Acrobat.

If you are serious about protecting your documents, then you will probably want to purchase a PDF file security product that is not password-based – read PDF password protection to see why – and uses US Government strength encryption.

Download PDF file security software that uses US Government strength encryption, digital rights management controls, and does not use either passwords or plug-ins to secure your PDF documents.

  Can you secure PDF files for free?

It depends on what you consider ‘secure’.

While you can password lock a PDF with an online tool for free, it’s trivial to remove the security from the PDF file again.  It’s unlikely that you will find a free solution that is able to effectively protect documents.

  How to remove security from a PDF file

As mentioned, the password protection used in Adobe Acrobat is not a good way to secure PDFs.  Flaws in the Adobe Security handler make it completely trivial to edit a secured PDF file – as we’ll show you below.

Here’s how easy it is to edit a secured PDF file from Adobe:

  1. Upload the document to an online password remover tool
  2. Enter the open password
  3. Wait for the website to strip the permissions password
  4. Download the modified PDF and edit it in any PDF editing software


If the user does not have the PDF open password, it doesn’t mean they can’t remove the protection – just that they need to crack the open password first.  This can be time-consuming, but it’s still entirely possible with a PDF security removal tool.

Locklizard Safeguard DRM cannot be bypassed using these tools.  It does not use passwords and its permissions aren’t based on an honor system.  Instead, a combination of strong encryption, a secure viewer application, DRM controls, and a transparent licensing system keep your PDF files safe.

  Is it safe to secure a PDF online?

Some PDF security applications enable you to protect PDF files online on a cloud server (securing PDF files in the cloud).

Most of these programs, however, only provide standard PDF password protection.  The other major disadvantage of this approach is that you have to upload unprotected PDF files to a cloud server where they could be easily compromized.

A much more secure way of securing PDF files is to do so on your local computer (offline), and then distribute the encrypted files online.  This ensures both your unprotected and secure PDFs are always under your control.

  How to print a PDF file that is secured

Printing a secured PDF file that has been protected using a password, is just as easy as editing one.

You can use the method above to strip print and editing protections, or open it in an editing program that doesn’t honor Adobe’s permissions, such as Word, Google Docs, or a Mac PDF editor.  Users can print straight to a file too, creating an identical copy of the PDF with no controls applied.

  How to copy from a secured PDF file

There are various ways to copy from a secured PDF file, provided it has been protected with an ineffective tool like Adobe Acrobat or an online PDF password protector.

The first and easiest method is to upload the document to an PDF password removal program or website.  This will strip Adobe’s permissions and allow you to do whatever you wish with the document, including copying and pasting.

If printing is enabled, you could instead drag and drop the PDF into a Chrome browser window, press the print icon, then print it to a PDF.  This will create a version without the copy/paste restrictions.  Alternatively, you can upload it to Google Drive and open it in Google Docs.

Finally, if none of that works, you still have the option of screenshotting the document and uploading the image to an OCR recognition site.  The site will convert the image of the text into real characters that you can copy and paste.

  Can you comment on a secured PDF file?

Locklizard Safeguard DRM lets you comment on and highlight a PDF file even if it has been protected.  Unlike Adobe Acrobat, it does so without compromising the document’s security.

Further reading on PDF Security

To learn more about the PDF security, read the following white papers.

  PDF Security and Encryption
   How Secure is Adobe PDF Security?

Also see PDF Security Issues which covers flaws and cracks in various PDF Security implementations.

  Weak PDF Security Implementations

There is no point in applying controls if users can easily remove security from the PDF file.

  • PDF Passwords

    PDF password protection has been the traditional way to impose PDF digital rights management controls on PDF document users, but it has several drawbacks.  One problem in password-based PDF file security is that a number of suppliers provide tools for removing the protection controls on the basis that you are the document owner and you have ‘forgotten’ how to use a document that is yours.  The weaker the password, the sooner it is broken.

    In Adobe Acrobat, you can add a number of additional controls (PDF permissions) such as stopping printing, editing, and copying text when you secure a PDF file with a password.  However, because the Adobe implemented its Security Handler poorly, users can remove PDF restrictions in seconds no matter how strong the password used to secure the PDF is.  So, reliance on some of the controls being provided is not as wise as it seems – they are totally useless.

  • PDF Plugins

    Some PDF Security products use plugins to prevent unauthorized use and to control what users can do with documents.  However, plug-ins may (and often do) act in conflict with each other, and other plug-ins may be used to compromise the security of the PDF file.

    Also, the Adobe PDF Reader was not designed to operate in a secure manner, and it is not possible, as a plug-in, to control what the application can do, so any ability to compromise the application will also compromise the security.  See PDF Security Plug-ins.

    PDF file security is achieved when the different components work together correctly.  So, if some of the controls are implemented by one supplier and others by another, you need to make sure that the combinations work together.

    Plug-ins cannot compromise Locklizard PDF Security because we use our own Secure PDF viewers that prevent plug-ins from being loaded.  We supply and control the environment so that no vulnerabilities can be introduced.

  • Web based PDF security systems

    Web-based PDF security systems, such as those used for secure online document sharing, may seem convenient, but they still use passwords that users can be share with others.  Additionally, since no software is installed on the device, they cannot control Operating System behavior. This lets users can screen grab content or print to file drivers (e.g. Adobe PDF) if printing is allowed.

    Strong web-based PDF security systems, such as Locklizard’s, let you control the number of times a user can log in simultaneously and let you lock document use to specific locations so that PDF files cannot be readily shared.

  Strong PDF security software to secure PDF files & documents


Safeguard PDF Security gives you complete control over your PDF files, preventing unauthorized copying, modifying, printing and distribution.

Securely share or sell PDF files by controlling who can access them and enforcing how long they can be used, no matter where they reside.

Safeguard PDF security enables you to:

  • stop copying & editing
  • stop or limit prints
  • expire and revoke access
  • stop screen shots
  • watermark PDFs with dynamic data to identify users

Protected PDFs are locked to authorized devices so they cannot be shared with other users and PDF files are decrypted in memory so there are no unprotected files that users can distribute.

  Why Locklizard for PDF Document Security?

US Gov Strength PDF Security – Secure PDF files without passwords

Locklizard takes your document protection seriously.

Our DRM PDF Security products enable you to share documents securely without insecure passwords or plug-ins, and enforces access, location, expiry, and usage controls.  Your PDF files remain safe no matter where they reside, with the ability to revoke them regardless of their location or device.

See our customer testimonials or read our case studies to see why thousands of organizations use Locklizard PDF security to securely share and sell their documents.

Customer Testimonials