Excel Software has shopped Doc Protect 4 for Mac OS X (10.7 or later) and Windows. It’s an update of the application that allows an author to protect popular file types to ensure the docs are only viewable on licensed computers.

Version 4 can protect an EPUB file by embedding a reader and licensing process in the protected document. Other enhancements include improved PDF protection that supports the latest versions of Adobe Reader.

In addition to delivering a protected document as a Mac or Windows application, DocProtect 4 supports a new delivery vehicle, the SafeWebApp viewer. DocProtect can generate a protected file that’s activated for a specific device and viewed within SafeWebApp running on a variety of platforms.

SafeWebApp is free and runs on Mac, Windows, Linux, and Android platforms. DocProtect 4 costs US$495 for a single user license on either Mac or Windows — or $795 for both platforms. It includes royalty-free runtime distribution rights for unlimited documents or licenses. Go to http://www.excelsoftware.com for more info.