A jAuth driver must implements jIAuthDriver interface. It is roughly equivalent to jAuth API (but does not derive form it).

jAuth loads drivers and the drivers do all low level jobs (database access or ldap acces or text file access and so on)

If example is your driver name:

you create a classe exempleAuthDriver, in a file named exemple.auth.php, and locate it in auth/example directory of a plugins repository.

To activate your driver, you have to set driver option in your auth plugin configuration file. Still in this file, you can add an example section and fill below all your driver specific options.

   driver=example
   
   [example]
   foo=bar