Paper 2006/040

Linkable Democratic Group Signatures

Mark Manulis, Ahmad-Reza Sadeghi, and Joerg Schwenk


In a variety of group-oriented applications cryptographic primitives like group signatures or ring signatures are valuable methods to achieve anonymity of group members. However, in their classical form, these schemes cannot be deployed for applications that simultaneously require (i) to avoid centralized management authority like group manager and (ii) the signer to be anonymous only against non-members while group members have rights to trace and identify the signer. The idea of recently introduced {\it democratic group signatures} is to provide these properties. Based on this idea we introduce a group-oriented signature scheme that allows the group members to trace the identity of any other group member who issued a signature while non-members are only able to link the signatures issued by the same signer without tracing. For this purpose the signature scheme assigns to every group member a unique pseudonym that can be used by any non-member verifier to communicate with the anonymous signer from the group. We present several group-oriented application scenarios where this kind of linkability is essential. We propose a concrete linkable democratic group signature scheme for two-parties, prove its security in the random oracle model, and describe how to modularly extend it to the multi-party case.

Available format(s)
Cryptographic protocols
Publication info
Published elsewhere. The extended abstract of this paper appears at ISPEC 2006.
democratic group signaturesanonymitypseudonymitylinkabilitygroup communication
Contact author(s)
mark manulis @ rub de
2006-02-06: received
Short URL
Creative Commons Attribution


      author = {Mark Manulis and Ahmad-Reza Sadeghi and Joerg Schwenk},
      title = {Linkable Democratic Group Signatures},
      howpublished = {Cryptology ePrint Archive, Paper 2006/040},
      year = {2006},
      note = {\url{}},
      url = {}
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