I have ntp-4.1.73-2. When it starts up, it logs this:
Mar 17 06:42:50 jik ntpd: configure: keyword "authenticate" unknown, line
And indeed, the line "authenticate yes" appears in the /etc/ntp.conf that ships
with this version of ntp. Either the conf file is wrong or ntpd is confused.
we don't use this version anymore, please report that to the ntp developers