Make the protection certificate valid for one-time only

[MuhJWbD]

Hello,

I know how to protect a pdf and save the private key. after saving the private key any person have this key and install it to his/her computer will have access to the pdf. If I am creating my pdf and sharing it with students with the same key for everyone they will be able to share it with others, so how can I make a private key that is valid only for one time (a single computer only) If there is no such a way, what is other suggests that you have for the mentioned incident?

Thanks,

[Test Screen Name]

If your budget has 5-6 figures and your students don't work on mobile consider DRM software. But remember students can still photograph their screen or do other tricks. And students are motivated and able to do tricks. Probably best to rethink your aim.

[MuhJWbD]

I notice that students might be able to do tricks, but I want to protect my contents as much as I can. I have found a great freeware do the job, here is it's called Secretpdf you can found it here: Secret PDF - Free PDF DRM Software

Thanks,