Hi John,
One small technical point - passwords are one-way hashed not encrypted - the difference being there is no way to "decrypt" them other than comparing a hash of the plain-text password to make sure it matches.
From 2.5 onwards passwords are hashed using the bcrypt algorithm, with a per-user salt and the default PHP cost factor. We use the functions that are built in to PHP (http://php.net/manual/en/ref.password.php) along with a compatibility library to provide support for older versions of PHP in versions that support earlier php versions.
Using Bcrypt for password hashing is considered industry best practice.
Simon