Authentication and Security - Mastering phpMyAdmin 3.1 for Effective MySQL Management - page 26

The next time we start phpMyAdmin, we will see the login panel as shown in the
following figure:
By default, phpMyAdmin displays (in the login panel) the last username for which
a successful login was achieved for this particular server, as retrieved from the
permanent cookie. If this behavior is not acceptable (if we would prefer that someone
else who logs in from the same workstation should not see the previous username),
we can set the following parameter to FALSE :
$cfg['LoginCookieRecall'] = FALSE;
A security feature was added in phpMyAdmin 2.6.0—a time limit for the validity
of the entered password. This feature helps to protect the working session. After a
successful login, our password is stored in a cookie, along with a timer. Every action
in phpMyAdmin resets the timer. If we stay inactive for a certain number of seconds,
as defined in $cfg [ 'LoginCookieValidity' ], we are disconnected and have to log
in again. The default is 1800 seconds.
The Blowfish algorithm used to protect the username and password
requires many computations. To achieve the best possible speed, the
PHP's mcrypt extension and its accompanying library must be installed
on our web server. Otherwise, phpMyAdmin relies on an internally-
coded algorithm, which works, but causes delays of several seconds on
almost every operation done from phpMyAdmin! This is because the
username and password information must be decoded on every mouse
click to be able to connect to MySQL.