Quote:
Publishers
The most common distribution model for today's electronic document publishers requires the seller to prepare a unique copy of the file for each buyer. PDF Merchant removes this barrier by enabling publishers to encrypt the content once, distribute it everywhere, and sell the access keys to consumers. Since the keys are tied to the buyer's computer, no one other than the buyer is able to access the document. Someone trying to open a file without a valid key is sent to the seller's Web site to purchase it.
Taken from the Adobe web site... at