Anonymous Role-based Delegation With Group Signatures

We propose a decentralized trust management model called anonymous role-based cascaded delegation. In this model, a delegator can issue authorizations on behalf of his role without revealing his own identity. Anonymous delegation protects sensitive membership information of a delegator and hides the internal structure of an organization. Certificates used in anonymous role-based cascaded delegation model can be signed using any type of group signature scheme. However, in ubiquitous computing, users may have mobile computing devices with narrow communication bandwidth and small storage units. To make credentials efficient to store and transmit, we construct a group signature scheme that supports aggregation. We explain why an aggregate group signature scheme cannot be trivially obtained using existing aggregate signature scheme and one-time signing keys. Improvements in the credential size brought by using signature aggregation are compared with existing group signature schemes.