Rainbow Table Attack on 3rd Generation GSM Telephony Secure Algorithm – A5/3
T Anand1, M Shanmugam2, B Santhoshini3

1T Anand, Department of CSE, VFSTR University, (A.P), India.
2M Shanmugam, Department of CSE, VFSTR University, Guntur (A.P), India.
3B Santhoshini, Department of CSE, VFSTR University, (A.P), India.
Manuscript received on 12 February 2019 | Revised Manuscript received on 02 March 2019 | Manuscript Published on 08 June 2019 | PP: 86-95 | Volume-7 Issue-5S4, February 2019 | Retrieval Number: E10170275S419/19©BEIESP
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© The Authors. Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC-BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Abstract: GSM is a digital cellular network standard to send the customer’s data or voice through the air in mobile communication. GSM standard spreads over more than 80% of population in all over the world. The security of customer’s data is protected in the GSM by A5 family of cryptosystem. We are working on A5/3 cryptosystem used by the 3rd generation GSM for transmitting secured information through the air. The A5/3 cryptosystem is a stream cipher and having a key generator based on KASUMI block cipher. The A5/3 acccepts 64-bit input and gives a pair of 114-bit block output under the control of 128-bit key. Because of the large key space for the A5/3, we decided to work on a reduced version of the A5/3, called T5/3. The T5/3 accepts 32-bit input and gives a pair of 64-bit block output under the control of 64-bit keys. We are using TMTO(Time Memory Trade Off) technique to attack the T5/3 cipher. Rainbow table attack is a TMTO based technique and is feasible for the T5/3 cryptosystem. There are two phases, the offline precomputation phase and the online lookup phase in Rainbow table attack. The precomputation phase is a time consuming process and the lookup phase is a real time process which retrives the key used for the T5/3 cryptosystem. We have generated different sized Rainbow table and successfully attacked the T5/3 cipher. We have analyzed different parameters used in the Rainbow table attack like Distinguish Point(DP), Reduction Function(RF) and Collision. The Reduction function is a mapping from cipher text to a key in the keyspace. The Reduction function doesn’t have much significance in the chainlength and the collision in Rainbow table. Distinguish points are certain conditions which allows the reduction in time for the searching of key in lookup phase. If the DP value is more then the chianlength, collision and time to generate the Rainbow table are also increases.
Keywords: GSM, Cryptosystem, Rainbow Table Attack, Ciphertext, A5/3.
Scope of the Article: Algorithm Engineering