Either they did it one at a time using Acrobat or, they use an expensive digital rights management system (very likely).
But they definitely did not do it using the free Reader.
It sounds to me like standard password security, as opposed to DRM. As graffiti mentioned, this can be done with Acrobat, but there is a lot of other software out there that can secure PDFs. Some is suitable for use on a server so it can be automated. Some off the top of my head include PDFlib PLOP, some component of Adobe's LiveCycle/ADEP offerings, Appligent's APCrypt, and Debenu's QuickPDF library.
So what do I need to be able to assign each customer with a unique password to access the same PDF file?
George - I've sent inquiries to a couple of the companies you mentioned to see if one of their products has this capability.
Do I need to hire a programmer to create unique password access to the PDF? Or is there some company that sells such a solution?
Manually assigning passwords for each customer is not practical.
I'm assuming that what you were given is a PDF with a document open password. If this is the case, they probably has some automated process that determined a password and applied it to the PDF, and delivered the unique secured PDF to you along with the password.
If you decide to use standard password security, you should consider peronalizing the document with details about the custoomer as well. For example, each page could contain their name, or you could add the details to the document metadata. This too can be done with some of the software I mentioned.
If you provide more details about how you intend to sell your documents, someone may be able to provide more guidance.
I can create for you a stand-alone app that can read a list of names/passwords and produce a set of copies of a PDF file, each one with the unique password from the list.
If you're interested, contact me personally by PM or at try6767 at gmail dot com.
Look at the document properties and it'll say what software was used to create the PDF file.
I expect they are using a library such as TCPDF or FPDIP, which can apply encryption to PDF files at the moment they're served. It's an extremely-common way to deal with digital downloads, and provided your webserver runs PHP it doesn't cost anything, just requires some programming skill.
George - what I will be selling is a 650-page PDF eBook. Given the amount of content (especially the quality of the content), it's worth protecting it. LockLizard and such products are too high for a startup like mine. They are geared more for the enterprise business level.
Dave Merchant - I right clicked on the PDF eBook I mentioned in my original post that seems to have a unique password for each customer. On the 'general' tab, it says at the bottom:
"Security: This file came from another computer and might be blocked to help protect this computer."
I'm not sure if that tells you anything.
What's interesting is that after I cancelled the order for that $20 eBook product, the password still works - so the company using that password system either does not have the capability to revoke access or they simply forgot to revoke access to the eBook for me personally.
BTW, I found out that e-junkie.com has a PDF stamping option that will stamp each buyer's PDF with their name, email address, and transaction number. That would help. But I would still like to have the customer have to login with a unique password or key code to access the eBook contents. Having tenchology that revokes access to the eBook would also be ideal, but that might be too expensive to implement.
In order to be able to revoke access, you would need to use DRM, which as you've found is costly to implement.
To see what security is applied to the document, open it and select "File > Properties > Security".
File > Propterties > Security doesn't show anything insightful on their file other than it requires Adobe 7.0 or later and is protected by password security.
If you're still interested in a tool like this, I've just published one on my website, here:
It is a stand-alone tool (so no Acrobat required) which can produce any number of encrypted copies of a file you wish, using a variety of settings for botht he owner and user passwords, including generating random passwords.
See the link above for the full info...