| Abstract |
The GSM standard is the most widely used cellular technology. It has been designed to be a secure digital mobile telecommunication system with strong subscriber authentication and over-the-air transmission encryption. Currently it is supposed to be one of the most secure systems for mobile communications. However, the study of the security mechanism proves that GSM systems suffer from critical errors, enabling an attacker to go through the security model and perform an interception or a phone cloning. The objective of this thesis is the design and development of a system for Monitoring and Measurement of GSM Mobile Telephony Signals, taking advantage of the easy access to the physical interface air-interface as well as exploiting modern insecurities of such a system. For achieving this goal we made a study of GSM architecture and specially the air-interface and set the requirements of such a system. We implemented the basic set of GSM protocol stack, spanning from source coding and channel coding to ciphering and accessing the physical media the air-interface, developing the fundamental software and using special hardware modules. Furthermore, we made an extended reference on GSM security model and mechanism and presented a variety of possible interception attacks exploiting system vulnerabilities, using the implemented architecture. Finally, we evaluated this architecture emphasizing on the most important constraints that make such a system difficult to be used on existent networks. Besides, we proposed further optimizations and possible extensions of this work.
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Παρακολούθηση και μέτρηση σημάτων κινητής τηλεφωνίας GSM
