With advanced encryption standard’s counter with cipher block chaining-MAC mode (an authenticated encryption algorithm designed to provide both authentication and confidentiality),the packet data unit payload (after encryption) has a format as shown in Fig. 5. Here packet data unit payload is prepended with a 4-byte packet number. The packet number is transmitted with the least significantbit firstand the packet number itself is not encrypted. The packet number associated with a security association is set to ‘1’ when the security association is established and a new trafficencryption key installed. After each packet data unit transmission, the packet number is incremented by ‘1.’
On uplink connections, the packet number is XORed with 0x80000000 prior to encryption and transmission. On downlink connections, the packet number is used without such modifiction. The ciphertext message authentication code is transmitted such that byte index ‘0’ is transmitted firstand byte index ‘7’ transmitted last.
The result
WiMAX users should feel confdent that their transmitted data is free from eaves-dropping or manipulation and only authorised users can access WiMAX services. The improved WiMAX technology implements improved security architecture. Thus the operator ensures that only authorised subscribers access the network and use appropriate services subscribed by them.
The author is a research scholar pursuing Ph.D in electronics engineering from Indian Institute of Technology, Banaras Hindu University (IIT-BHU), Varanasi
