Sorry if this is in the wrong place.

I have Xenforo and Zenphoto on a sub domain. I'd like Zenphoto to use Xenforo as user control or a bridge.

Xenforo uses bcrypt. I have the sql to connect to xenforo tables etc. I just need help to get it all working. Please message me if you're interested and we can discuss fees etc.

"select substring(data, 23, length(data) - 25) from xf_user_authenticate xua join xf_user xu on xua.user_id = xu.user_id where xu.username = %s AND xua.scheme_class = 'XF:Core12'"
Require group allowed
"select 'allowed' from xf_user where (find_in_set('3', secondary_group_ids) OR find_in_set('4', secondary_group_ids) OR find_in_set('47', secondary_group_ids) OR find_in_set('49', secondary_group_ids) OR find_in_set('50', secondary_group_ids)) AND username = %s"

Sorry, I reallly cannot help, I have no knowledge about Xenforo at all…

You can create a custom authentification by creating your own zp-core/lib-auth.php file handling this. See the in file comments about that. You would have to maintain that yourself as there might naturally be changes (and there will be in the future).

I did some research on Xenforo. The results are not promising. See for instance https://xenforo.com/community/threads/login-logout-register-from-outside-xenforo.65878/#post-709906

Simply knowing that Xenforo uses the BCRYPT hashing algorithm is not enough. BCRYPT requires a hash seed. Without that there is no means of matching the hashing. Presumably that seed is a site specific secret to Xenforo else the password handling would not be secure.

The only reasonable approach would be to use the Xenforo login handler, but apparently that is a daunting task. From the time spent as per the above link, a custom implementation would cost thousands of dollars.

If Xenforo ever adopts OAuth logging in a single sign on would be feasible. I have built LDAP single login for Zenphoto/MyBBS and the code is only about 500 lines. But MyBBS supports the LDAP standard.