Secure PDF Files on thumb drives?

No, it's not. While you can set security on a PDF to make printing difficult, there is no viable way to restrict the file itself from being copied or distributed.

Even the digital rights management systems such as Livecycle and Adobe Digital Editions don't prevent copies of their files from being made; they just check if the logged-in user is allowed to open it or not. In your application I guess DRM wouldn't be a practicable option anyway, as you'd need to individually assign licenses to the files on each drive to the particular student who received it.

Thanks, UVSAR - I have read some of your other posts and was hoping that you might respond.

DRM might still be an option. I would like to register and watermark the PDF copies for each Student so that I know the source of any unauthorized copies.

The next question, still based on the first question; are there special thumb drives that allow the developer to create a read-only copy on the thumb drives (not an Adobe product). I think there would be great demand for a non-copy thumb drive so I could give a "book" to a student that they could always read, but never copy, and then hopefully the Adobe package could insert the watermarks and prohibit printing.

One of my customers claims that another training provider of different courses has done just that, but the customer is not allowed to put me into contact with the other provider.

No, it's not possible. By definition to open any file in an application on your computer, the data within the file must be transferred from the external drive into memory - so a copy can always be made by the same process. Even if you can't open the file (a secured PDF with an unknown password) provided the drive is readable you can still move it about on disk, email it to people, etc. There have been some disastrous high-profile attempts to prevent disc copying (notably by Sony) by installing software that hacks into the user's operating system but it's been ruled illegal and cost those trying it a fortune.


Bear in mind that a DRM solution is going to be very expensive and potentially annoying for users - for the files to be opened, the license must be checked with the DRM server, so you as the author must lease an almost-perpetual account with such a server (running your own is beyond the budgets of all but the likes of iTunes). Users must have regular Web access to verify their access - though DRM can allow a grace period between checks, you can't escape from the need to connect. They also expect to be able to make legitimate backups of things they "own" - a right enshrined in copyright law for many countries.

It's important to consider if the cost (including the overheads of dealing with the complaints, account setups etc. for each recipient) of the security solution is higher than the losses should a copy be shared illegally. It's less likely that those costs are justifiable than you'd think - which is why most of the online music vendors are moving back to DRM-less MP3 sales.

Thanks, UVSAR -

Not the answer I was hoping for but I appreciate the education.

Regards - Cliff