Mobile data services across the Internet pave the path for a society of tomorrow. Users will be able to access data, information, and services independent of their location. This will ease the way of business and private life, such as for the travelling field engineer repairing electronic devices at the customers’ premises by downloading a new control software or the family on vacation accessing on their Personal Digital Assistant local maps and information on tourist attractions. Having these applications in mind, the Internet technology as it exists today has to be enhanced by a number of different features. An important one is the infrastructure for Authentication, Authorization, Accounting, and Charging (AAAC) those mobile services. These functions will ensure that mobility will not happen into places where not authorized and will enable a commercial operation of a network, which offers services to be sold, such as services with varying Quality-of-Service (QoS) or different security degrees. Therefore, existing approaches, such as the traditional AAA (Authorization, Authentication, and Accounting) Architecture of the Internet Research Task Force (IRTF) have to be enhanced and equipped with performing and suitable functionalities
