Resisting Traitors in Linkable Democratic Group Signatures

Maged Hamada Ibrahim

《International Journal of Network Security》 9卷1期 (2009/07) Pp. 51-60

https://doi.org/10.6633/IJNS.200907.9(1).08

並列摘要

Linkable democratic group signatures (LDGS) [29] allow every member of a group to trace the identity of any other member who issued a signature while non-members (with the help of unique pseudonyms) are only able to link the signatures issued by the same signer without being able to trace the signer's identity. LDGS avoid centralized management authorities (group managers) and grant each group member the power to trace and identify the signer. Although LDGS add nice properties to group signatures, allowing each member of the group to trace the signer's identity requires a full trust in each group member not to trace or disclose the identity of the signer without a legal reason (e.g. a dispute). Such a requirement represents a major obstacle in practice. The existence of at least one saboteur member inside the group totally violates the anonymity attribute which is the main merit of group signatures. Such a traitor may reveal the identity of the signers to non-members without being detected. In this paper we introduce a simple, yet efficient traitors resistant LDGS (TR-LDGS) as a security improvement to the LDGS scheme of [29] to resist traitors in the sense that, the power to trace and disclose the identity of the signer must not be in the hands of each member. Instead, the power to trace and identify a signer will be distributed among the members of the group such that a fraction (majority) of the members may join together to trace and reveal the signer's identity while no minority coalitions are able to perform this task or to disturb the correct and legal progress of this task.

並列關鍵字

Democratic group signatures ； group signatures ； linkability ； threshold cryptography ； zero-knowledge proofs