Method and device for anonymous signature with a shared private key

摘要

A cryptographic method and apparatus for anonymously signing a message. Added to the anonymous signature is another signature which is calculated (operation 13 ) using a private key common to all the members of a group authorized to sign and unknown to all revoked members. The private key is updated (operations 8, 11 ) at group level on each revocation within the group and at member level only on anonymous signing of a message by the member.