Um, I think you want to look into using a session for this kind of data.

A session is a set of data maintained on the Web server that is uniquely associated with a single Web browser instance (normally via a cookie setting) -- so the user can enter their password once (hopefully via https), transmit it to the server, and have the server keep it locally until the end of the session (explicit log out or default time out).

See CGI::Session for one implementation of the standard solution for this kind of problem.