What about adding this at the beginning of _authenticate()

#return true if htpasswd-file is empty and transparent is working, no 
need to check more
         if (empty($this->_params['htpasswd_file']) && $this->transparent()) {
                 return true;
         }

From the _authenticate method header:

      * Find out if a set of login credentials are valid. Only supports
      * htpasswd files with DES passwords right now.

You could open a request for enhancement to extend the capabilities of 
the http auth driver though. No idea if it's on anybody's radar right 
now though.

Hi,

if i try to sync, i get "401 Unauthorized". Looking deeper in the code 
i found the cause (but i don't understand ;-)

in file Horde/Auth/Http.php

function _authenticate

$this->_users is empty, so i get an exception:


         if (empty($credentials['password']) ||
             empty($this->_users[$userId])) {
             throw new Horde_Auth_Exception('', Horde_Auth::REASON_BADLOGIN);
         }

$credentials['password'] has my correct passwd and $userId has my 
email-address.


Backtrace:
1. Horde_Rpc_ActiveSync->getResponse() 
/srv/www/mygretchen.de/htdocs/member/horde/rpc.php:156
2. Horde_ActiveSync->handleRequest() 
/usr/share/php/Horde/Rpc/ActiveSync.php:150
3. Horde_ActiveSync->authenticate() /usr/share/php/Horde/ActiveSync.php:562
4. Horde_Core_ActiveSync_Driver->authenticate() 
/usr/share/php/Horde/ActiveSync.php:406
5. Horde_Core_Auth_Application->authenticate() 
/usr/share/php/Horde/Core/ActiveSync/Driver.php:148
6. Horde_Auth_Base->authenticate() 
/usr/share/php/Horde/Core/Auth/Application.php:126
7. Horde_Auth_Http->_authenticate() /usr/share/php/Horde/Auth/Base.php:151
8. Horde::debug() /usr/share/php/Horde/Auth/Http.php:86

for Basic Auth i'm using apache with mod_auth_imap, no htpasswd file.

But if i switch horde-Auth to 'Application: imp' everythings works fine.

if i make _authenticate() return true, it seems to  work for me with 
http-auth.