A Threshold Group Signature Scheme with Multi-policy
Common threshold signature has not traceability,only one threshold value,poor security. In practical application,the threshold value of threshold digital signature depends on the significance of the document.Important document needs more the number of the co-operated users than common document to sign the document.We can solve the problem by using any existing threshold scheme repeatedly,but it isn't efficient.The paper proposed a scheme that multi-secret is shared by group member and different group secret has different threshold value to sign different document.Furthermore,group manager can delete old group member or add new member according requirement.