Attribute Based Group Key Management

Attribute based systems enable fine-grained access control among a group of users each identified by a set of attributes. Secure collaborative applications need such flexible attribute based systems for managing and distributing group keys. However, current group key management schemes are not well designed to manage group keys based on the attributes of the group members. In this paper, we propose novel key management schemes that allow users whose attributes satisfy a certain access control policy to derive the group key. Our schemes efficiently support rekeying operations when the group changes due to joins or leaves of group members. During a rekey operation, the private information issued to existing members remains unaffected and only the public information is updated to change the group key. Our schemes are expressive; they are able to support any monotonic access control policy over a set of attributes. Our schemes are resistant to collusion attacks; group members are unable to pool their attributes and derive the group key which they cannot derive individually. Experimental results show that our underlying constructs are efficient and practical.