7-Zip is not shipped by default with Microsoft Windows or Mac OS X. If you need to use your 7-Zip files on those platforms you will need to install the appropriate version of 7-Zip on those computers. See the 7-Zip download page
GNOME's File Roller application will recognize your .7z files and attempt to open them, but it will fail with the error "''An error occurred while loading the archive.''" when it attempts to do so. This is because File Roller does not currently support the extraction of encrypted 7-Zip files. A bug report ([https://bugzilla.gnome.org/show_bug.cgi?id=490732 Gnome Bug 490732]) has been submitted.