iTunes Artwork--a PNG app icon for showing in iTunes and the App Store.
iTunesMetadata.plist—Contains copyright information, release date, purchase date, name of the developer and company who created it, etc.
/Payload/Application.app
To repack the ipa, simple select the three files and folder listed above and right click and select compress. The Archive.zip you get can be install using ideviceinstaller. You can also rename the file name you wanted.
cd <the-directory-that-store-the-three-files-and-folder>
zip -0 -y -r out.ipa .
#or use
zip -0 --symlinks --recurse-paths out.ipa .
# the `out.ipa` is the result