Key-policy attribute-based encryption scheme for general circuits

Through introducing the access structure into attribute-based encryption, users can achieve the fine-grained access control to the ciphertext. Any access structure can be realized by general circuit. Therefore, designing attribute-based encryption for general circuit is difficult in this field. Garg etc. presented the first general circuit access structure based on multilinear maps. However the usability of the access structures is rather limited as gate can only output layer by layer and the depth of the circuit are fixed in l. In order to solve this limitation, this paper proposes a key-policy attribute-based encryption scheme for general circuits based on the Garg's scheme. In key generation step, the new scheme implements any circuit that depth is greater than 1 and less than or equal to l by equivalent conversion of the circuit and addition of the conversion key. It also achieves cross layer output by adding its child node depth into every non-leaf node's key component. Selective security of the proposed scheme in the standard model is proved under the decisional multilinear Diffie-Hellman assumption. © Copyright 2016, Institute of Software, the Chinese Academy of Sciences. All rights reserved.