The main Enigma theme, Pentagonal Dreams, is:

    Copyright 1995 Andrew Saga (a.k.a. Necros) <asega@ic.sunysb.edu>
    All rights reserved

And is provided to the Engima project on an informal license that allows
redistribution with the project.

For past discussion on this in the Debian project, please see:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=321669#20

Also see:

https://www.nongnu.org/enigma/manual/enigma_5.html#SEC38