WatchDox, a file sharing service for highly sensitive documents, announced it has raised $9 million in its latest round of funding.

WatchDox helps companies share highly sensitive data across across several devices and collaborate on documents in a secured environment. The service is like a more secure version of DropBox for businesses and government agencies.

Before a file is even shared, WatchDox also provides layers of security to documents to restrict how they can be viewed and shared. With a Microsoft Office plug-in, document owners can control whether or not a shared file can be printed, copied, or emailed. You can even set limits on how long someone else can access the document and track geographically where the document has been downloaded or viewed. And if someone downloads a file secured by WatchDox and then looses the device, the file can be remotely destroyed.

Similarly to Google Docs, WatchDox’s Workspace lets you create documents that can be worked on by a team of people in a protected environment. You can control who can access a specific data room, where sensitive documents can be upload and worked on by a group of people.

WatchDox’s service is available as a plug-in for Microsoft Office and Outlook, two native applications called WatchDox Uploader and Sync, and with iOS and Blackberry apps. The company is developing an Android app.

WatchDox faces competition from Accellion, which also offers secure file sharing and document collaboration for businesses across multiple devices and YouSendit, a secure file sharing service.

This latest round of funding for WatchDox was led by investment firm Blackstone, which announced it will begin using WatchDox’s services.

WatchDox has previously raised $14.4 million from Shasta Ventures, Gemini Israel Funds, and Shlomo Kramer. The company is based in Mountain View, California and was founded in 2007.

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