lsfr with odd charecteristics

hi, Book says, a construction that involved computing LSFR's over a field of 'odd charecteristics' is insecure. Does that mean a register with odd number of bits is insecure which would mean a tap sequence which uses an odd degree polynomial is insecure? Regards Data. __________________________________________________ Do You Yahoo!? Yahoo! - Official partner of 2002 FIFA World Cup http://fifaworldcup.yahoo.com