Secure PDF Files

How to create secured PDF files without passwords

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  Securing PDF documents and files

When creating secured PDF files, you first need to determine the protection and controls you require.

How secure are PDF passwords?

Simple PDF password encryption might be okay if you trust the recipient and are not worried about them easily removing the password protection, but it’s not particularly useful outside of that. The simple removal of editing or printing controls makes them more of a suggestion than a real security measure.

Simple encryption, meanwhile, stops unauthorized users from opening files, but it does not stop copying, printing etc. once an unauthorized user has opened a document.  That is where Digital Rights Management (DRM) solutions come into play.  Licensing controls further strengthen protection by locking PDFs to devices and IPs to stop sharing and use in unauthorized locations.

How to create a secured PDF document without passwords using Locklizard

Every PDF that is secured by Locklizard is automatically protected using AES encryption, DRM controls and licensing with transparent key management.  There are no passwords to enter, share or remove.  Users cannot edit a secured PDF, print or copy text, or remove security.

Here are the basic steps to secure a PDF file:

  1. Right-click on the PDF you want to secure and select ‘Make Secure PDF’.

    Creating a a protected PDF file

  2. Select the restrictions you’d like to apply, including restricting access after a certain date, which can be found in the “Expiry & Validity” tab.  By default, editing, copying, and printing are disabled.

    Restrict editing without passwords using Locklizard Safeguard PDF DRM

  3. Press the Publish button to secure the PDF document and apply restrictions.  On pressing the Publish button, Locklizard will create a secured PDF file, which can only be opened by users you give access to in the Safeguard Admin portal.  It can’t be edited, and content cannot be copied and pasted.  Printing is also blocked by default unless you specifically allow it.

    Publishing a PDF using Locklizard Safeguard PDF DRM

  4. Add new users, and/or select existing users you want to give access to your secure PDF files using the cloud-based Safeguard Admin System:

    Safeguard Admin system

  5. Distribute your secure PDF documents just like any other file – email them or let users download them from your website or file sharing site.  It does not matter who downloads your secured PDF files (.PDC files) as only those authorized will be able to view them.

How to remove security from a PDF

  Why passwords make for poor security

Adobe Acrobat and similar apps create password-protected PDFs.  All passwords are crackable with enough time, and this includes the open passwords required to access protected Adobe PDF files.  Most open passwords are not long or complex because they need to be easy to remember and convey.  This leads to situations where they can often be cracked in seconds with password removal software.  Alternatively, a user that knows the password can simply remove it and then share it with anybody they like or provide the PDF along with its password.

The permissions password or owner password (used to restrict editing, printing, and copying security) is much easier to remove.  The process can be performed by numerous online apps, as outlined below.

  How to print a secured PDF

  1. Upload your PDF to a PDF password removal service and then download the unprotected copy.
  2. Open the unprotected PDF in Adobe Acrobat reader (or any other PDF reader) and print as normal.

Note that Locklizard Safeguard does not allow printing restrictions to be removed and does not use passwords.  If you want to print a Locklizard protected document then you have to ask the Publisher for permission.

  How to save a secured PDF

You can save an Adobe secured PDF as many times as you like, even without removing its protection.  However, if you want to save an unsecured version, the process is as follows:

  1. Upload your PDF to a PDF password removal service and then download the unprotected copy.
  2. Make any changes to the document in your PDF viewer and then press “File > Save As”.

  How to edit a secured PDF

  1. Upload your PDF to a PDF password removal service and then download the unprotected copy.
  2. Press “Edit PDF” in your Adobe Acrobat sidebar or use a similar PDF Editor.
  3. Modify the content as you require.

  How to copy text from a secured PDF

  1. Upload your document to a PDF password removal service and then download the unprotected copy.
  2. Select the text and press Ctrl + C or right-click to copy it.

PDF protection options & security issues

When creating a secured PDF file environment there are many features and functions that must work together if you are going to be successful, from the PDF protection method to locking PDFs to locations.

Here we discuss each of these in more detail below.

  • PDF Protection method

    The first question to consider when creating a secured PDF is how easy it is for others to remove the security.

    The most popular method for creating  secured PDF files was and still is password protection, but passwords are easily removed using any of the PDF password recovery programs – see PDF Encryption & Security.  If you truly want to secure your PDF files, passwords are clearly not the way forward.

    Some businesses use secure document sharing sites such as secure data rooms but these have many security weaknesses.  Users can share login info, and modify or disable JavaScript to remove protection.  See Google Docs Security as an example of how easy it is to remove security from a PDF file and other document formats.

    Adobe Content Server used PKI technology (see Public Key Infrastructure), to replace passwords – see password or certificate encryption – but that meant that the publisher needed the customer’s public key in order to create a unique secure PDF file.  When using its PKI, a PDF file had to be protected independently for each individual recipient.  The same PDF file could end up being secured hundreds or thousands of times depending on how many recipients there were.  This was not a readily scalable architecture, particularly if your business went global.

    Locklizard DRM secured PDF files only need to be encrypted once and use long and random encryption keys.  Decryption keys are required for authorized users to open protected PDF documents.  They do not travel with the PDFs themselves but are instead transparently relayed securely to the recipient’s device and stored encrypted in a keystore.  There are no passwords for users to enter so there are none to share, and users don’t have to send their public key to anyone.

  • Preventing sharing

    If you use passwords to create secure PDF files, then users can easily share both the PDF file and the password with others.

    Unauthorized recipients won’t be able to open a Locklizard DRM secured PDF since it is encrypted.  To open a Locklizard PDF, the user has to be both registered with the publisher and authorized to view it.  To stop users from sharing the PDF file along with their keystore, the keystore is locked to their individual device(s) and if it is copied to another device it will not work.

  • Preventing forwarding

    You can’t prevent users from forwarding secured PDF files (or indeed any files) to others.  Even if a corporate email policy system is in place, users will find a way around the system (e.g. saving the file to disk and sending it by webmail, usb stick, converting it to a zip file, etc.).

    What you can prevent, however, is the opening of the PDF file on an unauthorized device.  This is because unauthorized recipients cannot use a PDF file without the publisher’s authority, which is controlled via the Locklizard administration system.

  • Preventing copy and paste

    There is not much point in creating a secure PDF file if authorized users are allowed to copy and paste content from it.  It’s a bit like building a strong prison and then leaving the gaol door open.

    Locklizard PDF DRM software prevents copying and pasting by using our own secure viewer environment to limit the functions available to users.  We prevent plug-ins from being loaded so that third party plug-ins cannot compromise the system by enabling features or bypassing other controls.

  • Preventing editing

    If users can edit or add to the content of a secured PDF, then they have to be able to copy and paste as a minimum, and likely have Save and Save As functionality too.  And as we already covered, allowing copy and paste is a bad idea.

    In theory, you could allow Save/Save As functionality and create new encrypted files, but then there would be version control questions, access rights management hurdles with the new document, and so on to deal with.

    So, on both counts, allowing editing is not compatible with secure PDF use.  Locklizard PDF DRM products prevent saving and editing of PDF documents as a result.

  • Preventing screenshots

    Locklizard employs various techniques to prevent the use of printscreen and third-party screen grabbers.

    Whilst DRM cannot totally prevent screen grabbing from taking place (nothing can stop a photograph of the screen from being taken with an external device), it can make the task more laborious (and expensive).  When combined with other controls such as dynamic watermarking, it can also discourage users from grabbing screen content in order to share copies.

  • Preventing printing

    Stopping users from printing a PDF file is one of the most effective ways of preventing copies of your documents from being circulated since printed documents can be readily photocopied or scanned and then duplicated.  But it may be a requirement to let users print.  If you want to allow printing, then Locklizard DRM software enables you to apply secure watermarks (see Watermarking on view and/or print).  It can also enforce degraded printing, limit the number of high-quality prints allowed, and log print requests made by users so you can watch out for inappropriate behavior.

    Locklizard PDF DRM software automatically prevents printing to PDF and other file formats so that PDFs cannot be readily converted to unprotected files.  Also, documents that have been printed, scanned back in, and then converted to PDF will only be image documents (so basically one big image in a PDF file).  They lose all the bookmarks, embedded links, and text search capabilities – which are key usage differentiators of electronic documents over paper copies.

  • Dynamic Watermarks

    Publishers can add dynamic watermarks to secured PDF files that automatically insert the user’s name, email, company name, and a date/time stamp at print time to discourage sharing of printed documents.  Once a user knows a shared printed copy will be immediately traced back to them, they’re much less likely to do so. Similarly, these dynamic variables can be inserted at view time to discourage screenshots from being taken and distributed.

    Because Locklizard DRM software uses dynamic variables, the publisher only has to protect one PDF document for all users.  With Acrobat PDF security, you have to protect each PDF file individually for each user to customize it with their user details.

    Locklizard DRM software also allows static watermarks (text and graphic images) to be applied at the same time as dynamic ones.

  • Document expiry

    Document expiry can be enforced either on a fixed date or following document usage rules.

    There are many reasons you may want to expire PDF documents such as:

    • to comply with document retention policies
    • to enforce version control
    • trial usage (e.g. 1 or 2 views before purchase)
    • enforcing compliance with disclosure requirements
    • enforcing subscription periods to a service or series of documents

    Locklizard PDF DRM software enables you to expire PDFs:

    • After a number of views
    • After a number of days
    • On a fixed date
    • After a number of prints
    • When a subscription period has ended
    • At any time you decide
  • Tracking opens & prints

    Tracking if or when a  document has been opened or printed can be essential for accountability or auditing purposes.  You may need to prove that the recipient has not only received the PDF file but has also read and/or printed it.

    You can track and monitor PDF use by recording document opens and prints and displaying the number of times each document has been opened and printed by each user.

  • Locking use to locations

    There may be occasions when you do not want confidential or important documents to leave your office premises.  But with BYOD, this has become a difficult problem to solve.

    Locklizard enables you to lock PDFs to specific locations (say an office) so that documents will only be viewable from this location and no other.

    Location locking can be enabled on a global or user basis and at both country and IP levels.

  • Revoking access

    Being able to revoke access can be vital when confidential documents have been distributed or where chargebacks have been applied against a purchase (e.g. a book, a report, or a training course).

    Publishers can revoke access at any time, ensuring your documents are always under your control.

  • Use in thin client / virtual environments

    Being able to limit the number of computers that a PDF can be viewed on is at the heart of any DRM licensing system.  However, most DRM systems don’t prevent the viewing of PDF files in thin client / virtual environments.  If a PDF file can be viewed in a thin client or virtual environment then it means that a secured PDF licensed for a single computer can be used on all computers in that environment.  It may make you question why you bothered to secure it to begin with.

    Locklizard automatically prevents the use of secured PDF documents in thin clients and virtual environments unless they have been specifically authorized by the publisher of those files.

  • Allowing offline use

    Not everyone wants to be (or is able to be) connected to the internet every time they open a PDF.  Some PDF DRM systems force the user to always be connected to the internet when they want to view and/or print a secured PDF file, or even to be online the whole time it is in use.

    Locklizard supports both online and offline use.  You can require users to always be connected to the Internet (so checks can always be made with the licensing server for any updates – like removal of access, etc.), make them go online every n days (e.g. check with the licensing server once a month for any updates), or allow them to view and print PDF files permanently offline.  The latter gives the publisher less control and means they cannot instantly revoke access, but it does provide greater flexibility for the user.  In the case of some documents, such as ebooks, this may be a market requirement.

  • Zero Installation Viewers

    Some business may not always be able to install software, so Locklizard provides zero installation viewers for locked PDF files.

    We have two types of zero installation Viewer:

    • Safeguard Web Viewer– enables users to view PDFs in a browser (Google Chrome, Edge, Firefox, etc.) on any operating system or device.
    • Safeguard PDF Portable – is a method of loading a secure environment (Viewer, encrypted keystore and documents) onto a portable device such as a flash drive or USB stick.  Documents are linked to the USB stick instead of being linked to the computer on which they are loaded.  From a licensing perspective, it means that secured PDF documents may be used on any machine capable of running the viewer application.  This is exactly like owning a book in that the purchaser of the book may lend it to others (or even rent it), but only by giving it to them physically and thus being denied a right to continue to use it unless and until it is returned.

Why use DRM for Secure PDF files & documents?

DRM is, ultimately, really about responding to risk assessment.  You have to balance the need to protect information against the inconvenience the user may have in using it.  You must also juggle the expectations the user has about how they can use information against your requirements surrounding what it is that you want to license and your business model.  That requires a granular series of overarching and overlapping methods and techniques since there is no one size fits all.

At one extreme, a determined thief can always sit down and reproduce, by hand, a copy of a secured PDF document they have authorized access to.  But this is time-consuming and expensive, and there may be a significant loss of quality to their product.  At another extreme, a hacker may try to develop an automatic method for removing security, and that is also expensive, complex, and uncertain, but not impossible.  Locklizard secure PDF solutions aim to provide you with tools that combine to make the various piracy approaches challenging to automate and difficult to reverse engineer.

Why Locklizard for Secured PDF files?

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 enforce access, location, expiry, and usage controls.  Revoke PDFs at any time regardless of where they are.

Our DRM technology ensures your PDF files remain safe regardless of their location.

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


What is a secured PDF?

A secured PDF refers to any document in the PDF format that has controls applied to stop unauthorized opening, printing, editing, or copying.

Can a secured PDF be opened?

It depends entirely on what was used to secure it.  Password-protected PDFs can usually be opened through the use of password-cracking tools in a matter of minutes or hours.  PDFs protected by Locklizard can only be opened by authorized users with a valid license file installed on their devices.

How do I unsecure a PDF that is password-protected?

You can unsecure a PDF (remove the permissions password) through various means, from online and offline password removal tools to simply opening it in a PDF reader that doesn’t support Adobe Permissions and saving it.  See Why password protecting a PDF is not secure.

How do you create a secured PDF?

You can create a secured PDF with Locklizard by right-clicking on a PDF document in Windows file explorer and selecting “Create Secure PDF”.  Publishing the document will automatically apply editing, copying, and printing controls that cannot be removed.

Can you change PDF security settings after distribution?

Yes, for PDFs protected with Locklizard, you can change access, print settings, expiry, and location controls.  See How to change PDF security settings after sending.

Does Locklizard support macOS?

You can only protect PDFs on a Windows PC but users can view secure documents on Mac, Windows, iOS, and Android.

Is it safe to send a secured PDF by email?

Absolutely, only authorized users will be able to open them.  See How to send a secure PDF.

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