Though it's been somewhat of a gray area, making a backup copy of 'purchased' copyrighted media has been regarded as permissible for personal use.
However, circumventing copy protection to make a copy is still only legal in U.S. under a few exceptions relating to academic, criticism, research, and accessibility. You can find more info from the Librarian of Congress.
Since some apps mentioned can be used for both backup and circumvention purposes, don't post specifics about their capability to break DRM or copy protection , as this potentially violates forum rules. Better discussed on other Internet forums.