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Cryptanalysis of WG-7: a lightweight stream cipher

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Abstract

WG-7 is a stream cipher based on WG stream cipher and has been designed by Luo et al. (2010). This cipher is designed for low cost and lightweight applications (RFID tags and mobile phones, for instance). This paper addresses cryptographic weaknesses of WG-7 stream cipher. We show that the key stream generated by WG-7 can be distinguished from a random sequence after knowing 213.5 keystream bits and with a negligible error probability. Also, we investigate the security of WG-7 against algebraic attacks. An algebraic key recovery attack on this cipher is proposed. The attack allows to recover both the internal state and the secret key with the time complexity about 227.

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Acknowledgements

Ron Steinfeld and Josef Pieprzyk were supported by the ARC Discovery Grant DP0987734. Ron Steinfeld was also partially supported by the ARC Discovery Grant DP110100628.

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Authors and Affiliations

  1. Center for Advanced Computing – Algorithms and Cryptography, Department of Computing, Faculty of Science, Macquarie University, Sydney, NSW 2109, Australia

    Mohammad Ali Orumiehchiha & Josef Pieprzyk

  2. Clayton School of Information Technology, Monash University, Clayton, VIC 3800, Australia

    Ron Steinfeld

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  1. Mohammad Ali Orumiehchiha
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  2. Josef Pieprzyk
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  3. Ron Steinfeld
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Correspondence to Mohammad Ali Orumiehchiha.

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This work was done while Ron Steinfeld was with Macquarie University.

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Orumiehchiha, M.A., Pieprzyk, J. & Steinfeld, R. Cryptanalysis of WG-7: a lightweight stream cipher. Cryptogr. Commun. 4, 277–285 (2012). https://doi.org/10.1007/s12095-012-0070-x

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  • DOI: https://doi.org/10.1007/s12095-012-0070-x

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