
Sales US Tel: 800 707 4492 UK & Europe Tel: +44 (0) 870 766 9379

Education -> Information security center -> PDF encryption

What is PDF encryption? - a beginners guide

PDF Security
PDF Digital Rights Management
PDF Password Protection
PDF Copy Protection

Security Learning Center
Information Security Glossary

PDF ENCRYPTION

What is encryption?

Encryption is the use of a mathematical system (algorithm) to make information secret from anyone not authorized to use it. Encryption uses a secret key to scramble information applied to files so that only those with the correct key can view them. PDF encryption is therefore the encryption of PDF files, the result of which is an encrypted PDF file.

Encryption keys are sometimes taken from passwords, but passwords are a poor choice for encryption keys – see PDF password protection. Encryption keys are usually very long, and their values are almost random, making them almost impossible to find and impossible to guess.

What is PDF encryption?

PDF encryption is therefore the encryption of PDF files and this may be carried out in a number of different ways. At the simplest level one can encrypt an entire PDF file. At a second level one could encrypt parts of the PDF information thus making the PDF file effectively unusable but without having to encrypt all of its content.

So why would I want to encrypt my PDF documents?

There are many reasons why you would want to use PDF encryption. The information in the pdf document is confidential and only a restricted number of people should be able to see it. This could include training courses, price lists, bid documents, takeover plans, healthcare records, and so on. The information is valuable – you sell it – perhaps a newsletter, or an analyst’s report, or a consulting report or a periodical or a book. You obviously don’t want to give it away!

If you don’t encrypt the PDF file then anyone can read it and the value of your information is lost. But if you are going to encrypt your PDF files you need to select a package using a reliable encryption method.

What should I look for in a PDF encryption software package?

Well, one that uses US Government strength encryption (and is not password based – read PDF password protection to see why). The US government has approved an algorithm called AES for protecting US government information that is confidential. It has two key lengths, 128 bit and 256 bit (16 or 32 bytes of data). You will see many other algorithms proposed in many products, but they do not have the recommendation of the US government to back up their claims.

Download PDF encrypter software that uses AES 256 bit encryption and digital rights management controls and does not rely on passwords to encrypt your PDF files. You control if your encrypted PDF documents can be copied, shared and printed (and how many times) and when they expire (if ever).

So how does PDF encryption differ from PDF Security or PDF Digital Rights Management controls?

Well, PDF encryption prevents those who are not authorized from using the PDF document. But those who are authorized to use it can decrypt it and then do whatever they wish with it – copy it, send it to friends, edit it, print it and so on. In some instances, such as transferring financial data for computer processing, encryption on its own provides all the requirements. But information in published documents such as the ones we listed above means you need additional controls to actively prevent a user who is authorized to see the document from doing other things that you do not want to approve.

For more information on extending controls beyond PDF encryption please see PDF security and PDF digital rights management.

Further reading on encryption

To learn more about encryption, please take a look at the following white papers.

PDF Security and Encryption

Encryption is not enough for DRM

PDF encryption guide - why you should encrypt pdf documents. Covers pdf document encryption, pdf file encryption and pdf encryption software. Lizard Safeguard PDF encryption software provides PDF document encryption. Encrypt PDF files with AES 256 bit encryption and PDF DRM controls.