An adaptively CCA-secure ciphertext-policy attribute-based proxy re-encryption for cloud data sharing

A Ciphertext-Policy Attribute-Based Proxy Re-Encryption

(CP-ABPRE) employs the PRE technology in the attribute-based en-

cryption cryptographic setting, in which the proxy is allowed to convert

an encryption under an access policy to another encryption under a new

access policy. CP-ABPRE is applicable to many real world applications,

such as network data sharing. The existing CP-ABPRE systems, how-

ever, leave how to achieve adaptive CCA security as an interesting open

problem. This paper, for the rst time, proposes a new CP-ABPRE to

tackle the problem by integrating the dual system encryption technology

with selective proof technique. The new scheme supports any monotonic

access structures. Although our scheme is built in the composite order

bilinear group, it is proven adaptively CCA secure in the standard model

without jeopardizing the expressiveness of access policy.