Cryptanalysis of WG-7  (A Lightweight Stream Cipher for RFID Encryption)

Mohammad Ali Orumiehchiha; Josef Pieprzyk; Ron Steinfeld

Paper 2011/687 Original: eprint.iacr.org/2011/687 ↗

Cryptanalysis of WG-7 (A Lightweight Stream Cipher for RFID Encryption)

Mohammad Ali Orumiehchiha

Josef Pieprzyk

Ron Steinfeld

Abstract

WG-7 is a stream cipher based on WG Stream Cipher and has been designed by Y. Luo, Q. Chai, G. Gong, and X. Lai in 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 $ 2^{13.5}$ 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 $2^{27}$.

Metadata

Available format(s): PDF
Category: Secret-key cryptography
Publication info: Preprint.
History: 2012-05-29: last updated; 2011-12-23: published
Short URL: https://ia.cr/2011/687
License: https://creativecommons.org/licenses/by/4.0/

BibTeX

@misc{cryptoeprint:2011/687,
      author = {Mohammad Ali Orumiehchiha and Josef Pieprzyk and Ron Steinfeld},
      title = {Cryptanalysis of WG-7  (A Lightweight Stream Cipher for RFID Encryption)},
      howpublished = {Cryptology {ePrint} Archive, Paper 2011/687},
      year = {2011},
      url = {https://eprint.iacr.org/2011/687}
}