Shell Programming and Scripting

$ date --date "Jan 1, 1970 + 365 days"
Fri Jan 1 00:00:00 CET 1971

...this is another way but i think you must search trough all options in date man pages...

ps: i dont use ksh

EDIT/ADD:
Anyway I suggest you to search with google something like: "epoch time converter" or "epoch date" and so on... you can find a lot of scripts

You don't state Operating System.
If you have the "logins" commands, the date of the last password change is available (albeit in MMYYDD format).
A script-readable format is:

Code:

logins -xto

Tip: Brand new accounts can look like dormant accounts until the first password expiry.