Best ways to secure your PDF

Victor Finkelstein
April 09, 2020

Losing sensitive data can costs companies a lot whether it be by losing customer's loyalty, company's reputation or even legal consequences. PDF files are really easy to share and a lot of online tools claim to help you to secure them but what are they worth? What is the best way to secure your PDFs? This article will discuss the most common ways to secure your documents and answer these questions.

#1 Password protection: the strongest option

Maybe one of the most popular and best ways to protect your PDFs is with a password. There are two passwords you can set on your file:

The first one is a password to prevent people from editing/printing your document. It is based on the document reader software so very weak. Let's face it, this is useless as it can be very easily removed. You can get rid of this type of password in less than 2 minutes with online tools.
The second one is a password used to encrypt the document itself and enables you to open and read it (image below). This type of password is much more secured. But there are a different things to consider.

First of all, the choice of the password is very important, if you choose a common password such as 123456789 or use dictionary words, your password is not safe at all. The most basic online tools to remove passwords on PDF can crack these in a few seconds as they test a lot of common combinations such as basic number sequences and dictionary words. Your best bet is to generate a random password containing letters, numbers and special characters of at least 12 characters to make it resistant to a brute-force attack.

Then, you shouldn't store any passwords on your computer. If you have a file and the password stored in the same place (your computer for example), if your computer gets compromised, your protected files are immediately compromised too. Remembering the password and never writing it anywhere is the best solution, but it's not always possible. A good habit is to store your passwords in special applications (such as 1Password or LastPass) and share them with members of your team. If you don't have applications like these, another way is to always send the password on a different platform than the file (for example, send the file by mail, and the password on Teams).

Finally, this solution is not suitable for a PDF that you need to send to hundreds of people. Sending the password to that many people greatly increases the risk of a leak as hundreds of people will have to use and maybe store your password.

Pros:

Very effective way to protect your PDF as it is encrypted

Cons:

A good password is needed
Not scalable, as it is not doable for PDFs distributed to a large number of people
Password's storage

#2 Watermarking: useful for largely distributed PDFs

Watermarking your PDFs is adding an image, or a text onto your content, to make it more difficult to copy or use your PDF without your permission. This can be useful especially if your PDF is meant to be distributed to a large number of people.

A big 'CONFIDENTIAL' watermark across your content will make people more careful about the PDF, but may not be enough. At UniquePDF, we strongly believe that adding a unique watermark on your PDF, that depends on the recipient (right image), can help increase the barrier to information leak. This watermark contains the recipient's email address, which means that each recipient will receive a different version of the PDF with their own watermark, making it 'more personal'. For more information and if you want to try it for free, check UniquePDF.

Pros:

Can be used to send PDFs to a large number of people

Cons:

Less secure than a password on an encrypted file.

#3 Redacting: not always the right solution

Redacting is the act of censuring or obscuring a part of a text for legal or security reasons. This tactic can be used in PDFs to remove personal or sensible data. However, simply adding a black line over the information that should be redacted is not enough: removing it is very easy with any PDF editor! The best way to redact is to actually remove the piece of content.

This method can not always be used as redacting a document means removing important pieces of information.

As long as the redacting does not prevent readers from understanding the document, it can be a good solution.

However, if too many things will be redacted in your PDF, you might want to consider the two first options we saw above.

Pros:

Effective if done right

Cons:

Important information may be missing from the document which makes it useless in some cases

What should you do to secure your PDF?

It depends on the number of peope you want to send your PDF to:
A password known and written by hundreds of people is not secured at all. Below a dozen of people, you should lock and encrypt your PDFs with a password. Above that number, it might be better to watermark and send them using UniquePDF or any other similar tools.
In addition to that, we have a premium feature at UniquePDF allowing you to watermark and lock your PDFs with a password, for even more security. Contact us for more information about this.