Does anyone know of a secure hardware clock solution for Linux?

Looking for a clock that once initialized has limited adjustment. Similar to device found on crypto cards.

Thanks

You can use ntp (ntpd) to set your "system" time based on a device such as a gps clock made for the purpose or even point to someone like the U.S. Naval Observatory's (USNO) clocks tick and tock as your source.

You could then use the hwclock command to keep your hardware clock in sync with your system clock. (You could make cron entries to do this on a regular basis.) In UNIX/Linux the system clock rather than the hardware clock is the one used while it is up and running. The hardware clock is only used on reboot to insure your initial system time is set.