GSMity Secur

1. Goals of Security features
The security features should be provided two sided i.e. from
the Operator Side as well as User Side
Operator Side: From operator’s point of view it should be
ensured that operators
• Bill the right person
• There should be mechanisms to avoid fraud
• Services should be protected

2. Subscriber side: The security measures need to be more promising and
precise on subscribers side. They should aim at
Maintaining privacy and anonymity of user which means that identification
and location of the subscriber should be concealed
Confidentiality of communication over air should be maintained by
providing proper encryption methods
There should be strong access control mechanisms for devices
and SIM card
Only authenticated users should be able to access the network

3. GSM offers several security services using confidenti
al information stored in the AuC and in
the individual SIM. The SIM stores personal, secret
data and is protected with a PIN against
unauthorized use. Three algorithms have been specifi
ed to provide security services in GSM.
Algorithm A3 is used for authentication, A5 for encry
ption, and A8 for the generation of
a cipher key.

4. Principles of GSM Security
GSM provides security under following mechanisms:
Access Control to SIM card: This is done by use of Personal Identificati
on Number (PIN) to get access to the SIM card
Anonymity: Hiding the identity and location of user. This is done by
using a TMSI number
Authentication of subscriber so as to ensure only registered and au
thorized users have access to network
Encryption of Data and signal to protect them against interception

5. Access control and authentication

6. Confidentiality:

7. New Data Services
To enhance the data transmission capabilities of GSM, two bas
ic approaches are possible. As
the basic GSM is based on connection-
oriented traffic channels, e.g., with 9.6 kbit/s each,
several channels could be combined to increase bandwidth. T
his system is called HSCSD
{high speed circuit switched data}. A more progressive step is
the introduction of packet-
oriented traffic in GSM, i.e., shifting the paradigm from conne
ctions/telephone thinking to
packets/internet thinking. The system is called GPRS {general
packet radio service}.

8. GPRS Architecture

9. Home location register (HLR)
Visitor location register (VLR):
Authentication center (AUC):
Mobile switching center (MSC):
Base station subsystem (BSS):
serving GPRS support node (SGSN)
GPRS support node (GGSN)
Packet data network PDN