Chosen-Ciphertext Secure Multi-use Unidirectional Attribute-Based Proxy Re-Encryptions

This paper presents a novel cipher text-policy attribute-based multi-use unidirectional proxy re-encryption scheme. In the proposed scheme, the tree access policy can be used to handle and (¡Ä), or (¡Å) and threshold (of) operators. We first formalize the security definition against chosen cipher text attack for cipher text-policy attribute-based multi-use unidirectional proxy re-encryption schemes, and then prove the proposed scheme to be secure under ADBDH assumption in the standard model. Furthermore, compared with other cipher text policy attribute-based proxy re-encryption schemes, our scheme is more efficient and allows the encryptor to control whether the cipher text need to be re-encrypted.