Golbal System for Mobile Communications
Smartcard Developer Association
The Global System for Mobile communications (GSM) is the world's most widely
used digital mobile telephony system. With over 120 million subscribers
worldwide, the GSM network is the world's largest digital network of any
kind. The GSM network contains more nodes than even the Internet.
Cryptographic protections are employed throughout the GSM network, both for
authentication and voice-privacy purposes. Since the cryptographic
algorithms used within GSM had not been published outside the membership of
the GSM MoU, our group first reverse engineered the algorithms. We then
subjected the reverse-engineered algorithms to cryptanalysis.
We will present the three core algorithms used in GSM followed by a
presentation of cryptanalytical attacks on all three ciphers. Having
demonstrated that GSM mobile phones are subject to both cloning and
eavesdropping, we will trace the severe design flaws present in the GSM
algorithms to the fundamentally flawed design procedure employed by the GSM
MoU. We will conclude our presentation with recommendations for a better
design procedure that would prevent such flawed cryptographic systems from
entering production mode in the future.
For additional information about our work regarding GSM, visit the Smartcard Developer
the ISAAC Group.
Gates 498, 10/12/99, 4:15 PM