<sigh> I can't just quit the discussion, it appears.
@Ilasram: in fact, I am a programmer and have been involved in online systems since the pre-Compuserve era. Trust me, I understand cryptography, compression, OCR, etc. and have written systems ranging from online tax appraisal databases for governments to complete online ecommerce sites from the ground up. I've also been involved in print and publishing for decades, engineering RIPs, OCR software, developing fonts, multi-media content distribution, and so on. I emphatically do not think that individual private keys prevent universal reader applications from being written. In fact, one of the appealing features of the PK-based system is that just the opposite is true.
@Peter:
"Now, some programs won't honor it and open the content anyway or fake the license or allow you to save decrypted content, but these will exist no matter what. That's a legal, not technical problem. (Encryption just makes that legal problem a bit simpler to solve)." Exactly. Thank you.
@moz:
"Can you explain again how encrypting something so that only I can decrypt it stops me from sharing it once I've decrypted it? That's where I get confused." I would suggest the confusion comes in because 1) I never did explain this, so cannot explain it
again and in fact 2) have explicitly stated several times that stopping pirates from sharing their decrypted files isn't possible and isn't what we're talking about. Perhaps you're in the wrong thread?
For latecomers to the thread, please at least read post #1, #8, and maybe #22 and #30 before asking me to explain "again" how this prevents piracy, or before you point out the fatal flaw in the system: at some point you'll actually be able to read your book and thus can copy it!
OH, you got me.