Paper 2005/041

On the Security of a Group Signature Scheme with Strong Separability

Lihua Liu and Zhengjun Cao


A group signature scheme allows a group member of a given group to sign messages on behalf of the group in an anonymous and unlinkable fashion. In case of a dispute, however, a designated group manager can reveal the signer of a valid group signature. Many applications of group signatures require that the group manager can be split into a membership manager and a revocation manager. Such a group signature scheme with strong separability was proposed in paper [1]. Unfortunately, the scheme is insecure which has been shown in [2][3][4]. In this paper we show that the scheme is untraceable by a simple and direct attack. Besides, we show its universal forgeability by a general attack which only needs to choose five random numbers. We minutely explain the technique to shun the challenge in the scheme.

Available format(s)
Cryptographic protocols
Publication info
Published elsewhere. Unknown where it was published
Group signatureUntraceabilityUniversal forgeability.
Contact author(s)
zjcamss @ hotmail com
2005-02-16: received
Short URL
Creative Commons Attribution


      author = {Lihua Liu and Zhengjun Cao},
      title = {On the Security of a Group Signature Scheme with Strong Separability},
      howpublished = {Cryptology ePrint Archive, Paper 2005/041},
      year = {2005},
      note = {\url{}},
      url = {}
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