Encrypted swap is essential to securing any system using eCryptfs, since decrypted file contents will exist in the system's memory, which may be swapped to disk at any time. If the system swap space is not also encrypted, it is possible that decrypted files could be written to disk in clear text.
Note that most Linux distributions do not yet support resuming from an encrypted swap space, and thus hibernate/resume will not work. Suspend/resume is unaffected.
Upon running the utility, the user will be informed of the hibernate/resume break, and asked to confirm the behavior. The -f|--force option can be used to bypass this interactive prompt.
On Debian and Ubuntu systems, the complete text of the GNU General Public License can be found in /usr/share/common-licenses/GPL.