An Improved Identity-Based Society Oriented Signature Scheme

In a society oriented signature scheme, a signature is produced by several co-signers simultaneously in a group. Saeednia proposed an identity-based society oriented signature scheme. However, there are some security weaknesses in the scheme. Zhu and Wang et al. showed two different attacks against the identity-based society oriented signature scheme respectively. In this paper, we proposed an improved identity-based society signature scheme with anonymous signers. The proposed identity-based society signature scheme removed the weaknesses of Saeednia´s signature scheme. A detailed analysis demonstrated that the improved scheme is secure against all the attacks above-mentioned. In addition, when the structure of a group changes or a group represents different organizations to sign messages at the same time, the improved scheme won´t reveal the secret key of any entity or even the value of the ratio of two secret keys. Our scheme doesn´t require that the clerk must be a trusted and online party.