DokuWiki-Joomla-Bridge is a project mainly written in ..., it's free.
DokuWiki bridge to use Joomla Users
All additional informations for the bridge can be found in the old blog entries.
Copy the file dokuwiki/inc/auth/joomla.class.php
to your dokuwiki installation
Change the following line in your dokuwiki/config/dokuwiki.php
file
$conf['authtype'] = 'plain';
replace by
$conf['authtype'] = 'joomla';
If your joomla admin has a different name then admin, change the following line and replace admin by the specific username
$conf['superuser'] = 'admin';
Adjust the path to the joomla configuration file. The assumption is made, that dokuwiki installed inside the joomla folder.
include_once '../configuration.php';
Done. Login with your joomla users into dokuwiki.