Badinage: "O
bviously there are ways around these security settings (as with anything thesedays) but genrally they are secure!! "

Generally they're secure? I don't see how. Could you explain?

My logic goes that it is impossible to prevent editing. If you can read something, then you can edit it. You can put whatever DRM technologies you like in it but if at any point it reaches output, it is compormised.

It's like trying to stop music from being copied. You can put it in a DRM format, but the moment it reaches speakers then those speakers could also be recording it. And once it has been recorded, you can have it in any file format you like - and so, easily editable. You don't even need to reverse engineer the format if it's secret.

Well, I suppose the point is like many DRM technologies, it stops users who don't have the knowledge - in this case, how to use google...

A quick google turns up ww.cs.cmu.edu/~dst/Adobe/Gallery/PDFsecurity.pdf or in HTML http://216.239.59.104/search?q=cache:zTA8yxcJthYJ:www.cs.cmu.edu/~dst/Adobe/Gallery/PDFsecurity.pdf+PDF+security&hl=en

Don't rely on PDF or any format for stopping people editing. It's impossible! If you want to prevent people reading it, then encrypt it with some strongish encryption. (Recommendation would be PGP - although arguably the encryption of the data is done with IDEA cipher, IIRC.)

One notable exception to capturing and editing is a technology that I think (I could have imagined it, I can't remember it clearly) is distorting somehow (I said I couldn't remember it clearly) an image that a human would not notice (as the brain corrects it) but would make any recordings obfuscated. This, I would argue, is a failure in recording equipment and would still suffer the same problems if captured directly - i.e. not through a camera.