BAPI Authentification

Hello,

I'am looking for the best solution to manage BAPI Authentification.

I have a first authentification between the device and SUP Server. And i have another authentification between SUP Server and SAP CRM (BAPI).

What is the best solution to map the SUP user with the SAP user?

Notice : i haven't the choice, the 2 users are differents.

Thanks in advance.