BlackBerry Ltd. announced Tuesday that it has reached a deal to purchase a California-based company that makes technology to secure shared documents. The company being bought is called WatchDox Ltd. Terms of the deal were not disclosed. BlackBerry said in a press release that WatchDox' software allows organizations to view and control documents even after they have been shared among different devices. It gives businesses control over the editing, copying, printing and forwarding of documents, and allows them to revoke access or delete them remotely if circumstances warrant, BlackBerry said. The new technology will become "a value-added service that complements" BlackBerry's enterprise mobility management portfolio, the company said.