Authentication plugin to convert foreign passwords

[fxstein]

As part of the migration of non Joomla base forums we need to be able to migrate the passwords from e.g. phpBB format to Joomla format. Since the reverse engineering of passwords is not possible, we require an authentication plugin to intercept the password entered by a user.

If that user is in our migration table and it contains a migration password, we test the entered password aginst the migration password with logic from e.g phpBB3, if that fails we test phpBB2 (different format). If both fail, we abort the login attempt.

If we find a match, we know the right user and password combination has been entered. As such we store the entered password in the Joomla user table (properly encrypted) and remove the migration password from the migration table.

Next time the same user comes to authenticate, the migration table no longer contains a password and we go straight to Joomla authentication.

The code is based on Joomla 1.5 and 1.6 authentication plugins.