19-07-2011, 04:31 PM
Abstract—
GSM bears numerous security vulnerabilities.
Although GSM’s architecture is designed in such a way to
provide various security features like authentication, data/
signaling confidentiality, and secrecy of a user yet the GSM
channel is susceptible to replay, interleaving and man-in-themiddle
attacks.
The GSM speech service is secure up to the point where speech
enters the core network. However to achieve end-to-end security
it is desired that the GSM subscriber, not the network operator
controls the encryption on the speech channel. A new approach
of encryption at the user-end is introduced. In this paper we
have tested our encryption technique on the GSM
communication system using TMS320C6713 DSP Starter Kit
(DSK), in real-time. Our technique encrypts the speech before
entering the GSM handset which adds security and privacy. The
encryption algorithm being private to the communicating GSM
subscribers, the GSM channel will become exclusively
confidential for them. The DSK board was used as a separate
module of the system implementing the encryption algorithm.
Real-time experiments were conducted to check the performance
of the system in terms of its performance and latency rate.
Keywords-GSM; security; DSK; CCS
I. INTRODUCTION
Mobile phones are used on a daily basis by hundreds of
millions of users, over radio links. Emerging wireless networks
share many common characteristics with traditional wire-line
networks such as public switch telephone/data networks, and
hence many security issues with the wire-line networks also
apply to the wireless environment. Risks in wireless networks
are equal to the sum of the risk of operating a wired network
plus the new risks introduced by weaknesses in wireless
protocols. Thus, wireless mobile communication technology is
more vulnerable to security risks than fixed wired technology
as monitoring airwaves is a much easier thing to do [1].
Establishment of protective measures that guarantee a state
of inviolability from antagonistic acts is an important
requirement of wireless communication. Therefore a major
concern regarding the safeguard of the subscriber’s privacy
arises. The constraints of security include issues like, the
weaknesses and limitations of mobile and communications, the
architecture limitations, the user requirements, the contents of
provided services, and the evolution of hacking techniques.
The GSM system doesn’t provide end-to-end security and lacks
in provision of traffic confidentiality to its subscribers.
Anonymity, authentication, and confidentiality are the security
services which are offered by the world’s largest mobile
telephony system [2]. Still this system is defenseless against
many attacks and fails to ensure taut safety of the user’s
telephone conversations and data transfer sessions.
Confidentiality of transmitted data is achieved by
encrypting the information flow between the communicating
parties. In GSM networks, only the radio page link between the
mobile terminal and the base station is encrypted whereas the
rest of the network transmits data in clear-text. Radio link
confidentiality in GSM is not sufficient for attaining end-to-end
security. As a result, a need for investigating mechanisms for
implementing absolute confidentiality of traffic arises.
In this paper we have proposed a very practical and highly
attractive solution to the security lapses of the GSM system.
An embedded hardware system (i.e. TMS320C6713 DSK)
along with a simulation code developed in CCS (Code
Composer Studio 3.1) is used to encrypt the speech signals.
Tests were performed to evaluate the effect of encryption on
voice transmission in GSM-GSM connections. The GSM
system was examined in both scenarios i.e. transmission with
encryption and without encryption and the results were
obtained for comparison. DSPs are optimized for signal
processing applications compared to general purpose
processors (GPP). DSPs attractive feature is that actually the
number of instructions is reduced for efficient signal
processing. Hence, the DSP-boards made the system speedy
because of their dedicated processors and fast ADCs and DACs
[3]. This speed and accuracy would not have been made
possible with desktop computer’s slow processors.
In the following sections a complete picture of our
innovative proposition has been painted. Section II gives a
concise overview of the hardware equipment we have used, its
capabilities and advantages. Section III discusses the features
of the simulation environment used for developing our
algorithm. The proposed algorithm for encryption/decryption
and use of DIP Switches has been explained in Section IV and
Section V. Section VI and Section VII present the results of the
testing process and the conclusion drawn on their basis.
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