Abstract. A Ciphertext-Policy Attribute-Based Proxy Re-Encryption (CP-ABPRE) employs the PRE technology in the attribute-based encryption 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, however, leave how to achieve adaptive CCA security as an interesting open problem. This paper, for the first 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.
In 2014, Liang et al. REF , for the first time, formalized the notion of adaptive security for CP-ABPRE systems and proposed a new CP-ABPRE scheme, which is proven adaptively secure in the standard model, but their scheme demands a number of paring operations that imply huge computational overheads.
An Adaptively CCA-Secure Ciphertext-Policy Attribute-Based Proxy Re-Encryption for Cloud Data Sharing
ISPEC
Computer Science