GROUP SIGNATURES

Abstract

In this paper we present a new type of signature for a group of persons, called a group signature, which has the following propertjes: (i) only members of the group can sign messages; (ii) the receiver can verify that it is a valid group signaa~e, but cannot discover which gr~up member made (i) if necessary, the signature can be "opened", so that the person who signed the message is revealed. it; T h e group signatures are a "generalization" of the credential/ membership authentication schemes, in which one person ppves that he belongs to a &n 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 busted cenm is only needed during the setup; and in otha schemes, each pason can create the group he belongs to.