How to Password Protect a .PDF File with Adobe Acrobat Standard or Adobe Acrobat Professional
Adobe .PDF files have revolutionized our ability to send documents to each other in a fixed, standardized format. By using .PDF files, you can ensure that everyone can see a document exactly as you see it – no longer will a client see tables in a document differently than you do because they have a version of Word that is different from yours and doesn’t display tables the same way.
Because .PDF files are so lightweight, flexible, easy to send via email and therefore easy for everyone to read, it is sometimes important that a password is added to a .PDF file in order to provide some level of basic security on the document.
In order to add a password to a .PDF file, you must have a copy of Adobe Acrobat Standard or Professional . When I use the term “Acrobat” in the instructions below, I am referring to either Acrobat Standard or Acrobat Professional. Recall that Acrobat Reader is the free version of Adobe Acrobat, and is only for reading .PDF files. For a list of differences among the versions of Adobe Acrobat (Reader, Standard, Professional) see this post.
Note that while this tutorial only covers Adobe Acrobat Standard and 
rofessional, there are some third-party (e.g. non-Adobe) applications that can manipulate .PDF files. For a video tutorial about how to create .PDF files for free, see this video post.
1. Open the .PDF file in Acrobat. Under the Advanced menu bar heading select Security, and then Password Encrypt
2. You may then be prompted to acknowledge that you are changing the security settings on the document. This warning is so you don’t accidentally lock yourself out of a document. Go ahead and press Yes. Fee free to check the “Do not show this message again” box if you don’t want to be reminded each time you secure a document.
3. You will then be presented with the Password Security dialogue box. In the image below you will see the “Require a password to open the document” checkbox highlighted in red (the other colored boxes are for the additional security settings of restricting printing and editing of the document – please see this post for more information about these security settings).
4. Click this box and enter a password. You will then see a warning about third-party applications. This warning is Adobe’s way of saying that while all Adobe products support the password settings you have just made, Adobe cannot guarantee that ALL programs that can read .PDF files will honor your security settings. Click OK and once again feel free to click the Do not show this message again check box. Note that you may be prompted to re-enter the password you just selected to verify that the password is correct.
5. Click OK at the bottom of the Password Securitydialogue box. You will get a final prompt explaining that these settings will not be applied until you save the document again.
6. Go ahead and save the document. You should now see the words SECURED next to the file name in the title bar.
Your .PDF file is now password-protected.
Tagged Adobe Acrobat, PDF
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JABADI - File Secure Pro AdminJuly 18, 2011 at 1:09 pm
Putting an Acrobat password on a PDF file is, unfortunately, meaningless since the file and password can still be shared freely. The Acrobat copy/paste protection does not protect against common screen capture/sharing utilities which are available for free everywhere on the Internet. This makes it very easy for your PDF document to be accessed by unauthorized users.
To properly protect a PDF, the author must protect it using a anti-piracy service like File Secure Pro.
David WJuly 18, 2011 at 6:29 pmAuthor
Well yes and no. Passwording a PDF file is not meaningless — it really depends on your goals. If you are sending a document to a client that you don’t want altered or printed, for example, then setting a password is a good idea. I agree that it’s not foolproof — there are 3rd party programs that don’t always respect these passwords — but for basic functionality I believe it’s effective. It’s clear that a determined person can get to your information, and the effort it takes to use screen capture software to copy a PDF — at least in my opinion — is prohibitive for a long work.
But yes — if you are writing a book and you protect it with a password, there is little (other than honor) that prevents people from distributing the password for your work– and acrobat at this time does not support complex algorithms that would make different passwords for different purchasers. There are services out there, such as e-junkie, that allow you to provide a custom watermark on your PDF so that each time someone purchases your work, they PDF is watermarked wit their name. At least in this manner if the work gets distributed when it shouldn’t, you can track down the person who did it.