The global system for mobile communications (GSM) is the most popular standard that implements second generation (2G) cellular systems. 2G systems combined with general packet radio services (GPRS) are often described as 2.5G, that is, a technology between the 2G and third generation (3G) of mobile systems. GPRS is a service that provides packet radio access for GSM users. This chapter presents the security architecture employed in 2.5G mobile systems focusing on GPRS. More specifically, the security measures applied to protect the mobile users, the radio access network, the fixed part of the network, and the related data of GPRS are presented and analyzed in detail. This analysis reveals the security weaknesses of the applied measures that may lead to the realization of security attacks by adversaries. These attacks threaten network operation and data transfer through it, compromising end users and network security. To defeat the identified risks, current research activities on the GPRS security propose a set of security improvements to the existing GPRS security architecture.
Key Terms in this Chapter
Signaling System 7 (SS7): SS7 is a set of telephony signaling protocols which are used to set up the vast majority of the world’s public switched telephone network telephone calls.
Subscriber Identity Module (SIM): SIM is a removable smart card for mobile phones that stores network specific information used to authenticate and identify subscribers on the network.
Temporary mobile subscriber identity (TMSI): TMSI is a randomly allocated number that is given to the mobile the moment it is switched on and serves as a temporary identity between the mobile and the network.
Global System for Mobile Communications (GSM): GSM is the most popular standard for mobile phones in the world.
Second Generation (2G): 2G is a short for second-generation wireless telephone technology.
General Packet Radio Service (GPRS): GPRS is a mobile data service available to users of GSM.
Second and a Half Generation (2.5G): 2.5G is used to describe 2G systems that have implemented a packet-switched domain in addition to the circuit-switched domain.
International mobile subscriber identity (IMSI): IMSI is a unique number associated with all GSM network mobile phone users.
GPRS Tunneling Protocol (GTP): GTP is an IP-based protocol that carries signaling and user data with the GPRS core network.