2017, 39(11): 2724-2732.
doi: 10.11999/JEIT170072
Abstract:
Attribute-Based Encryption (ABE) scheme is widely used in the cloud storage due to its fine-grained access control. However, the single authority can lead to the trust issue and the computation bottleneck of distributing private keys in the original ABE schemes. To solve these problems, a distributed ABE scheme that consists of a number of central authorities and multiple attribute authorities, is constructed based on the prime-order bilinear group in this paper. Here, the central authority is responsible for establishing the system and generating the private key for the user, and a single private key is generated by only one central authority. In order to improve the stability of the system and reduce the calculation of the center authority, a plenty of central authorities are adopted. The attribute authority, which is independent of each other, is responsible for managing different attribute domains. At the same time, the ciphertext length of the proposed scheme has nothing to do with the number of attributes, therefore, it is a constant. The most important thing is that the decryption computation needs only two bilinear pair operations. The scheme is proved selectively secure based on q-Bilinear Diffie-Hellman Exponent (q-BDHE) assumption in the random oracle model. Finally, the functionality and efficiency of the proposed scheme are analyzed and verified. The experimental results show that the proposed scheme has both constant-size ciphertext and the ability of fast decryption, which greatly reduces the storage burden and improves the system efficiency.