Question: A long-time client has asked us to help screen their work machines for pornography. They're worried about liability if sensitive materials were found. Their main concerns (for obvious reasons) are video, audio, and image files. If possible, they'd also like to scan text-based documents for inappropriate content. They have a hierarchy of not-for-work content starting with blatantly illegal (I don't have to list details), moving down to obviously offensive, and also including things that may be offensive to some - think lingerie ads, joke cards featuring butt cracks, and anything related to Howie Mandel.

My questions are:

* Is this ethical? I think it is since every employee legally agrees that their work machine belongs to the company and is subject to search. The screenings are not to occur on personal machines brought to work.
* Is it feasible? I've done a lot of image processing/indexing but this seems like a whole new world of complexity.
* Any references to successful techniques for discovering porn?
* Is it appropriate for me to archive the results when something is discovered?

Answer: 
About legal aspects, in France:

The boss owns the computers and the internet connection: He can do whatever pleases him.

BUT, employee privacy cannot be violated. If a directory on the computer is labelled PERSONAL, the boss is not allowed to scan it.

The only way to bypass that is to get elements of evidence that employee stores illegal material and to get a court request a scan of computer (Note that pornography is not illegal in France.)
Everyone's computer operating system was probably installed from a disk image. 

1. start with the disk image and get a list of files you probably don't need to scan.
2. get a list of all the other files on each PC.
3. pull the actual files from 10-20 random machines and use as a test bed
4. search for items in a profanity and questionable word (hotties, jugs, 'barely legal', joke, etc) dictionary
5. View the video - should anyone have any video at all?
6. View photos
7. Any video or image files that are questionable can be used to search the other machines

It will take one or two employees to get caught before any one will put anything on their work computer.

Charge an obscene amount of money for this service. I'll be Zappos would never do this to their employees.