skeinsum is an implementation of version 1.3 of the Skein cryptographic hash 
function. It is licensed under version 3 of the GNU General Public License 
or, at your option, any later version. See GPLv3.txt for details. See the 
INSTALL file for installation information.

The skeinsum home page is http://jxself.org/skein.shtml.

Information about the Skein cryptographic hash function itself is available 
at http://www.skein-hash.info/