how to design space efficient revocable ibe from non-monotonic abe
Since there always exists a possibility that some users' private keys are stolen or expired in practice, it is important for identity based encryption (IBE) system to provide a solution to revocation. The current most efficient revocable IBE system has a private key of size O (log ns ) and update information of size O ( r log( n / r )) where r is the number of revoked users. In this paper, we present a new revocable IBE system in which the private key only contains two group elements and the update information size is O ( r ). We show that the proposed constructions for the revocation mechanism are more efficient in terms of space cost and provide a generic methodology to transform a non-monotonic attribute based encryption into a revocable IBE. We also demonstrate how the proposed method can be employed to develop an efficient hierarchical revocable IBE system.
revocable ibe non-monotonic attribute based encryption (abe)