In the physical world, when you share a record or a book with a friend, it's still technically yours. But in the digital world, where documents aren't so much shared as they are copied, it's difficult for content creators to maintain control.

Sharing a Word document chock-full of sensitive information isn't like lending out your beloved old copy of Paul's Boutique, after all. You can forward that document to multiple people, edit its contents, and print out as many copies as you want. And in most cases, the content creator is likely none the wiser. Clément Cazalot believed there had to be a better—and easier—way to keep such crucial documents in check.

Rather than create a paranoid tool for paranoid people, Cazalot and his cofounder Alex Negrea created DocTrackr, a file tracking service that also gathers usage analytics. The service tracks how and where documents are being viewed and shared—and boasts a handy kill switch to revoke access altogether, if needed—with the hopes of giving creators a better idea of how their content is being used.

Cazalot and Negrea previously worked in the innovation department of French security firm Gemalto before leaving to found their document-tracking startup over a year and half ago. After a stint in Paris with startup accelerator Le Camping, the pair have been working with TechStars Boston since January.

"If I send you a document by e-mail, Dropbox, whatever, the second you have it on your computer, I don't know where it is," Cazalot told Ars. "If I want to understand how you're using the document, we have no way to do that."

DocTrackr, on the other hand, makes gathering this sort of data possible. Now, if you can open a document in Word, PowerPoint, Excel or Adobe Reader, then you can track its use—and it doesn't require any additional software to be installed on a user's Mac or PC.

The process works something like this: your boss has an important document he or she wants to share with you and the rest of your team. Your boss uploads the document to DocTrackr, and sends each of you an invite over e-mail to view the file. Using what Cazalot calls "cryptography applied to document management," Microsoft Word or Adobe Reader checks with DocTrackr's authentication server to confirm whether access is allowed.

Because I care about the trees, I'm not going to let this Matthew Braga fellow print copies of the Ars Technica secret recipe.

And the type of access can vary too. Your boss might decide that no one should be able to print the file, or that the file should be read-only, and inaccessible offline. These permissions can be applied to everyone on your team, or just certain people. Or, if your boss has a new version of the document to distribute, access to the old file can be revoked. Meanwhile, the number of users who access the file, and for how long, are tracked and measured using a series of graphs online.

The genius here is that authentication is handled by security mechanisms already built into Microsoft Office and Adobe Reader, saving Cazalot from having to "reinvent the wheel." Instead, DocTrackr provides a simple, unified front-end interface to manage these permissions online—something a business would have previously had to handle itself.

However, this reliance on Microsoft and Adobe's approach to security is also one of DocTrackr's main caveats. A protected PDF or Word document—even if shared in an "unlocked" state—can't be opened using just any program. Because applications such as Preview.app on OS X or Open Office lack the necessary security features to verify access permissions on a protected file, the file can't be opened by anything other than apps from Microsoft and Adobe. Cazalot says this is unavoidable without having to develop and deploy additional software on each machine.

That anonymous usage data is what allows DocTrackr to measure and track file usage.

Currently, DocTrackr determines permissions based on e-mail, but Cazalot says the eventual goal is to use any form of online identification—say, a LinkedIn profile, or a Facebook account—as verification. The goal here is to "put intelligence on both sides of the table," so that files aren't only secured by the document creator's precautions, but by the closely guarded credentials of a user's social media account as well.

For now, the site is still in beta, and access to protected Microsoft Office documents, for the moment, appears to be down. However, Cazalot and Negrea are working to bring this and other features online quickly—including partner integration with cloud storage provider Box.

"One you share something outside of the managed cloud, you don't have anymore control," Cazalot said. "That's what we're trying to solve."

Update: Clément Cazalot has clarified that DocTrackr is meant to make document tracking an analytics easier, and is not intended to be a tool for paranoid people. The article has been updated accordingly.