How is time stored in the FireFox sqlite database "places.sqlite"?
It's not encrypted.

The db-schema is:

CREATE TABLE moz_places (   
  id INTEGER PRIMARY KEY, 
  url LONGVARCHAR, 
  title LONGVARCHAR, 
  rev_host LONGVARCHAR, 
  visit_count INTEGER DEFAULT 0, 
  hidden INTEGER DEFAULT 0 NOT NULL, 
  typed INTEGER DEFAULT 0 NOT NULL, 
  favicon_id INTEGER, 
  frecency INTEGER DEFAULT -1 NOT NULL, 
  last_visit_date INTEGER , 
  guid TEXT, 
  foreign_count INTEGER DEFAULT 0 NOT NULL
);


It's the field last_visit_date and is saved as Timestamp (Integer in milliseconds)
it means you could divide it by 1 000 000 and than use it as normal timestamp with seconds, when you don't need the precision of milliseconds.