Depending on what software you are using, this can be done at the actual PDF creation stage. Not all PDF creators or print drivers will allow you to add a password. You will need to check the help files of your software, but a general rule of thumb is…. if you are using a free product, then options may be limited, including the ability to add a password.
The benefits to password protecting your ebook are, that only those who have been given the password can open your files. There is software available to crack passwords, but at least you have made people work a little harder to gain unathorized access
If someone decides to share you download link with others on a forum or Facebook (how nice of them!), then they also have to share the password. Or if your download page is dicovered by other means, then the PDF download isn’t much use without the password. You could even upload a new version of your PDF (with a new password) on a regular basis, remembering to update the password details on your download page.
This only gives you limited protection. But limited is better than none at all.
Password protect with Nitro PDF Professional
This is quick and simple to do. Open up your Word document, and look for the Create Secure PDF icon.
Make your password at least eight characters, with a mix of letters and numbers. Leave the owner option box unchecked, to allow your customers the ability to print the PDF. Many people will want to do this.
Choose the 128 bit encryption level. Anything less than that is a waste of time, as free password cracking software can break this. 128 bit at least requires more advanced software to crack.
Password protect with DeskPDF
This gives the same 128 bit level of security as Nitro, but you have to look a little harder for the option to add a password. Once you get the save file window appear, look for the display advanced options checkbox.
Click on the security tab, to see the available options.
Is it worthwhile to password protect your PDF?
This is something you need to think about. Adding a password is an annoyance to your honest customers. Each time they open the document, they have to go through the process of inputting a password. And you can bet that some will be emailing you for help, after they forget the password. Which means that you need to allow for time eaten up answering these emails.
My personal feelings are: password protection is unnecessary for ebooks (in general) unless you have particular reasons to believe that you are vulnerable to ebook theft. However, if you take the steps outlined in the protect pdf files page then a password is probably not needed.
Also, consider that if someone who has purchased your ebook intends to share it, they also have the password. So you have done nothing to deter those sorts of people. Overall, I feel the drawbacks to password protection outweight the benefits.