The photograph is incorporated in a new product or simply stored in a computer system or digital archive for later use. Years later the purchaser of the picture decides that he wants to create a new slide show for a client. The photograph has the embedded watermarked DOI, and using the query form, the customer can send a message to the Directory to find the current owner and the current price for the photo. Another potential application might involve an infringement where a photographer finds a photograph on a web site and wonders if that particular picture is from his own repertory. You can imagine that a photographer with millions of images might not be so sure of every single picture he has taken but something about it feels familiar.
Authenticity checks Another problem that publishers face is concern over authenticity.
The DOI can be linked to the object as an authenticity check. These two numbers can be run through a program that will create a number sometimes referred to as a cryptographic hash, that can be used to immediately tell when the content has been tampered with. This system has two levels of protection. The first is simply a computation, which is useful for verifying to recipients that what they ordered is what they received. It is useful for publishers to provide them assurance that their customers are also getting what they intended and not something that has been in some way compromised.