Paper 2011/687

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

Mohammad Ali Orumiehchiha, Josef Pieprzyk, and Ron Steinfeld


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 $2^{27}$.

Available format(s)
Secret-key cryptography
Publication info
Published elsewhere. Unknown where it was published
WG-7 Stream cipherCryptanalysisKey Recovery AttackDistinguishing AttackWG Stream cipher.
Contact author(s)
mohammad orumiehchiha @ mq edu au
2012-05-29: revised
2011-12-23: received
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Short URL
Creative Commons Attribution


      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},
      note = {\url{}},
      url = {}
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