looking for a way to put a time limit on a cd

[DnetMHZ]

Heres my situation

I want to make a CD-R with documents on it to give out to clients/etc.
The problem is i need the CD to have a time limit on it.
I'm looking for a way to make it unreadable after a certain period of time
perhaps with an encryption utility that will not decrypt after a certain date.

any ideas?
thanks in advance

DnetMHZ

 

[yakko]

It would require software to be installed on the computer in question. If it is a business they will probably have other computers to play it on though.

 

[bot2600]

you could have a file encrypted file type that only your program could read. Have your program autorun off the cd and put a date on the cd when you burn it and have you program only work until x number of days after that date. But you would have to burn a fresh copy everytime you handed one out as the date would have to be updated.

Bot

 

[DeeK]

Even if you used a program to decrypt the files, they could read the files past the date just by rolling back the clock on the computer. So in short, there is no foolproof way to do what you'd like.

 

[RussianSoldier]

Unless, you put some type of internal clock located on the CD-R itself...

 

[pulpp]

two that comes to my mind, are a company called glassbook that makes e-documents security solutions, and also look around on adobe site, they also have thier own pdf based secure publishing solution.

 

[Pretender]

If the client's computers will have internet access, make it so the decrypt program accesses one of the government time servers (I can't remember the addresses right now, I'm not at home), that should be reliable unless someone decides to hack it...

 

[Atlantean]

I think that there is also something that lets you put a time limit on the cd once it has been loaded onto a computer, so that the data will be unreadable on that computer, but it doesn't apply to computers that haven't had the software loaded. yoau could always ask for the discs back or find some way to destroy them

 

[Moohooya]

There are several ways. The more foolproof the method the more expensive/annoying for the consumer. You need to decide how foolproof you want this.

The 100% foolproof way is to supply a dongle. They are small devices that plug into a serial port/usb/parallel port. It would contain a clock, and when that clock says time is up, it is up. You could even custom burn a cd per dongle to ensure the key was correct, so they couldn't get a new dongle from you and use the old cd. You could then have a drive that would only access the CD is the dongle reported all was OK.

The easy to hack solution, when the decrypt driver is installed, add the current date into the registry and every tim the program is run, check the registry. Easy to foil. You could reinstall, install on another machine, set the computer time back etc etc etc.

Get self expiring media. Not sure if this is available to the masses, but the idea is that after either
1) It has been read X times
2) It is Y days old
the media degrades to such a poor quality it can no longer be read. I don't know how reliable X and Y are, or what kind of ranges are available.

I like the idea about using an NTP server. Assumes that computer is on the net, but this is less of a restriction now than it used to be.

What is the CD, who are the customers, and how long do you want them to have it? If the cd will sell for thousands, do it the right way. If all you have is a bunch of clipart, just use the registry.

Moohoo