Cryptology ePrint Archive: Report 2012/208


Jay Shah and Ayan Mahalanobis

Abstract: In Europe and North America, the most widely used stream cipher to ensure privacy and confidentiality of conversations in GSM mobile phones is the A5/1. In this paper, we present a new attack on the A5/1 stream cipher with an average time complexity of $2^(48.5)$, which is much less than the brute-force attack with a complexity of $2^(64)$ . The attack has a $100\%$ success rate and requires about 5.65GB storage. We provide a detailed description of our new attack along with its implementation and results.

Category / Keywords: A5/1, GSM, guess-and-determine attack, stream ciphers

Date: received 16 Apr 2012, last revised 3 May 2012

Contact author: jayshah_89 at hotmail com

Available format(s): PDF | BibTeX Citation

Note: Some minor changes to the previously submitted paper. Also, a new table is added to the previous draft which has a comparison of all the previous known attacks with our new proposed attack.

Version: 20120503:061634 (All versions of this report)

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