Séminaire de Cryptographie

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Mark Manulis


Group Signatures for Federated Systems

For many mutli-party applications group signatures are important cryptographic primitives that can be used for the purpose of anonymity and privacy. In classical group signatures members of a group are able to sign messages anonymously on behalf of the group. However, there exists a designated authority, called group manager, that initializes the scheme, adds new group members, and is able to open group signatures, i.e., identify the signer. Obviously, in classical group signatures the group manager is given enormous power compared to other group members and is required to be trusted to act as predestinated. On the other hand there exist multi-party applications where such centralized control (trust) is undesirable, e.g., federated (democratic) systems. For this kind of applications it is desirable to have a group signature scheme which provides similar properties but is independent of any centralized control.