However, all existing CP-ABE schemes incur very large ciphertext size, which increases linearly with respect to the number of attributes in the access policy. Large ciphertext prevents CP-ABE from being adopted in the communication constrained environments. In this paper, we proposed a new construction of CP-ABE, named Constant-size CP-ABE (denoted as CCP-ABE) that significantly reduces the ciphertext to a constant size for an AND gate access policy with any given number of attributes. Each ciphertext in CCP-ABE requires only 2 elements on a bilinear group.
Based on CCP-ABE, we further proposed an Attribute Based Broadcast Encryption (ABBE) scheme. Compared to existing Broadcast Encryption (BE) schemes, ABBE is more flexible because a broadcasted message can be encrypted by an expressive access policy, either with or without explicit specifying the receivers. Moreover, ABBE significantly reduces the storage and communication overhead to the order of $O(\log N)$, where $N$ is the system size. Also, we proved, using information theoretical approaches, ABBE attains minimal bound on storage overhead for each user to construct all possible subgroups in the communication system.Category / Keywords: public-key cryptography / Date: received 12 Jul 2010 Contact author: zhibin zhou at asu edu Available format(s): PDF | BibTeX Citation Version: 20100713:232702 (All versions of this report) Discussion forum: Show discussion | Start new discussion