When using a api it is somtimes better to not have the extra overhead of keeping track of session. This is when basic authentication can be of use. Basic authentication simply is a header that is base64 encoded with a user name and password seperated by a :.

The setting needed in rdrrXaaa.ini to set up basic authentication

You need to set BasicAuthActive=1 to be able to use basic authentication. The header will then be read on every request to check for the Authorization header.

BasicAuthActive Tell system to accept basic authentication on the server. You can have both session and basic turned on, but if the is set to 1 and there is a Authorization heeader set, this takes preference to session.
BasicAuthFieldLevel The field used for security levels for basic authentication calls to the server. 
BasicAuthFieldPassword The field used for matching password given by the login process for basic authentication. Basic only support palintext passwords at the moment.
BasicAuthFieldUsername The field to lookup match for the username part of the basic authentication.
BasicAuthLevelDefault The default level assigned to a call set with basic authentication and where no level field is set.
BasicAuthTable Table to use for basic authentication.