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Related Key Cryptanalysis of the LEX Stream Cipher

Authors:
Mainack Mondal
Debdeep Mukhopadhyay
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URL: http://eprint.iacr.org/2010/011
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Abstract: LEX is a stream cipher proposed by Alex Biryukov. It was selected to phase 3 of the eSTREAM competition. LEX is based on the Advanced Encryption Standard (AES) block cipher and uses a methodology called "Leak Extraction", proposed by Biryukov himself. In this paper, we cryptanalyze LEX using two related keys. We have mounted a key recovery attack on LEX, which using $2^{54. 3}$ key streams yields a complete round key with $2^{102}$ operations. This improves the existing best cryptanalysis of LEX which needs $2^{112}$ operations to ascertain the key.
BibTeX
@misc{eprint-2010-22912,
  title={Related Key Cryptanalysis of the LEX Stream Cipher},
  booktitle={IACR Eprint archive},
  keywords={secret-key cryptography /},
  url={http://eprint.iacr.org/2010/011},
  note={ mainack.mondal@gmail.com 14718 received 10 Jan 2010, withdrawn 19 Apr 2010},
  author={Mainack Mondal and Debdeep Mukhopadhyay},
  year=2010
}