Using Passwords to Protect PDF Files
PDF open password, permissions password & PDF protection software
Password Protect PDF
Increasingly, people have become concerned that documents they send out, particularly in PDF format, may be open to re-distribution or misuse. Very often people do not want recipients to be able to change what they have done. And experience with Facebook has also taught people that they do not always want their documents made public without their permission. If the documents have commercial value this becomes even more important.
PDF files are often used because there is a misperception that they are ‘secure’ and cannot have been altered. But do they have security features such as password protection?
The first thing to be aware of is that there are a number of PDF security capabilities in the Adobe PDF standard document format (ISO/IEC 32000). These are:
- Require a password to open a document
- Require a password to change permissions restricting the
- editing and (quality of) printing of a document
- copying text, images and other content
- Apply a ‘digital signature’ to prevent forgery
So any PDF file can be password protected in order to control its distribution and use.
PDF Password Protection Software
Although you can use loads of applications to produce a PDF file in the Adobe standard format, not all of them will allow you to implement PDF passwords or digital signatures. It’s a bit hit and miss. For instance, perhaps the commonest application used to create a PDF is part of Microsoft Office. Their applications will allow you to set the password to open a document, but you cannot use them to change permissions or apply digital signatures.
The obvious choice of application for adding passwords to PDF files is Adobe Professional – the originator of the PDF file format. But you may find that their particular solution is not cost effective, or is not readily integrated into existing applications that you already have for creating or handling PDF documents.
Don’t worry, there are a plethora of other suppliers who will allow you to apply the standard Adobe password controls to PDF documents that you create with their applications. If you already have a PDF writer application just check that they provide those capabilities. If they aren’t able to do that then it depends on how much (or little) you want to pay. Suppliers who charge that you might want to look at include:
- Foxit Software
- A-PDF and similar
- or freeware such as pdfforge or CutePDF
- or a toolkit approach such as PDF-TOOLS.com
- or a server based approach like that of pdflib.com
These all work on your local machine and have refinements such as running in batch mode or digitally signing all documents within a folder.
Cloud based PDF Password Protection
If you would prefer to use cloud based services (in other words run the application that is applying the PDF passwords on somebody else’s server) there are quite a few suppliers you could consider, although they often don’t support digital signatures. These include:
- PDFProtect where you can apply passwords online or on your own machine but may have to accept advertising
- conv2pdf which has a size restriction of 6Mb
- pdfconvertonline who offer online or download solutions
- Appligent is an example of another approach of bundling additional services with either desktop or server based solutions
So you can apply PDF password protection easily to protect PDF files against unauthorized use, and there are a wide number of suppliers who support that approach.
But you have to look at whether PDF password protection is actually offering you the kind of document security you actually want. It is not very flexible and doesn’t tick many boxes when it comes to controlling the actual use of documents (how long are they available, can use be revoked, personalised watermarking on printing or viewing, and so on).
If you have several recipients and several documents you need to look at how you manage that situation. Check out the article on Working with PDF Passwords which looks at what you need to do to get PDF password controls work for you.
If you are looking for additional security and more comprehensive and granular controls than the basic password protection then you will need to look at specialist PDF DRM providers such as Locklizard who provide PDF security with enhanced controls, license management and administration services.
How to add password to PDF in Adobe Acrobat
- When you open a PDF document, click on the ‘Secure’ button on the Security taskbar.
- Select the option ‘Encrypt with Password’. When the dialog box opens, press OK. This verifies that you want the selected PDF to have password security applied to it. The Password Security Settings dialog box will then be displayed.
- Chose the “Require a Password’ in order to “Open the Document” check box. In the text box, enter a password and ensure that the password you use is more than seven characters with the inclusion of at least one number and special symbol. Press OK.
- Re-enter the PDF password and press OK once more.
This is one of the most primary forms of security you can add to a PDF file and it prevents unauthorized users from opening the document. If needed, additional layers of security can be added to the document such as limiting the editing and printing of the PDF document and this requires an additional password to be set – see PDF Restrictions below.
There are various document permissions you can set in Acrobat to control what users can do with your PDF files.
Below is a list of PDF restriction options available:
- Printing: If printing is not allowed, the print button in Acrobat will be disabled.
Adobe also lets you select high-resolution and low-resolution printing. Low-resolution printing generates a low quality bitmapped image of the page which is suitable only for personal use. Bitmap printing also considerably slows down the printing process.
- Changing the Document (editing): If this is disabled, any document modification is prevented. Content extraction and printing are allowed.
- Document Assembly: If this is disabled, inserting, deleting or rotating pages, or creating bookmarks and thumbnails is prevented.
- Content Copying: If this is disabled, selecting document contents and copying it to the clipboard is prevented. The accessibility interface also is disabled.
- Page Extraction: If this is disabled, extraction pages from the document is prevented.
- Commenting: If this is disabled, adding, modifying, or deleting comments is prevented.
- Form Fields: If this is disabled, form field filling is prevented.
- Signing: If this is disabled, signing documents is prevented.
- Content Accessibility: Allows accessibility software (such as a screenreader) to use the document contents.
Removing PDF Restrictions
PDF permissions are ‘protected’ with the use of an owner password. However the owner password can be easily removed in seconds with freely available PDF password removal tools. See Removing PDF Password Permissions.
Also third party PDF readers do not have to honor these controls which effectively renders them useless.
Secure alternatives to PDF Password Protection
Passwords are just the initial piece of protection for a PDF document. Keeping PDF files and documents safe requires an exhaustive procedure for powerful password conception and an easy to use method for users to conform to, to ensure the safety of the those passwords.
To ensure that your PDF documents are properly protected, consider opting for a professional document security solution that does not rely on passwords to keep documents safe. Not using passwords means you do not have to rely on users choosing strong passwords, storing those passwords securely, and administrators managing passwords on behalf of users.