Group signatures

TLDR

Group signatures generalize credential schemes by allowing a member to prove group membership without revealing identity. The paper introduces group signatures that enable members to sign anonymously while allowing optional traceability, and proposes four concrete schemes. Four schemes are presented, differing in cryptographic assumptions and trust models, from a setup‑only trusted center to fully distributed group creation.

Abstract

In this paper we present a new type of signature for a group of persons, called a group signature, which has the following properties: (i) only members of the group can sign messages; (ii) the receiver can verify that it is a valid group signature, but cannot discover which group member made it; (iii) if necessary, the signature can be opened, so that the person who signed the message is revealed. The group signatures are a generalization of the credential/ membership authentication schemes, in which one person proves that he belongs to a certain group. We present four schemes that satisfy the properties above. Not all these schemes arc based on the same cryptographic assumption. In some of the schemes a trusted centre is only needed during the setup; and in other schemes, each pason can create the group he belongs to.