Research On Attribute-Based Proxy Re-Encryption Scheme

Data files stored and shared safely and efficiently in the cloud server have become an important content in cloud computing research. In cloud computing environment, there is a lot of demand for encrypted data’s transformation. The cloud server is not fully trusted, if the ciphertext is decrypted and then re-encrypted by it, users will have the risk of data leakage. However, the proxy re-encryption technology allows users to complete the transformation of encrypted data with the help of a semi-trusted proxy server. In the process of transformation, the proxy service learns nothing about the data files. Therefore, the cloud service can realize data files’ sharing and access safely and reliably, also can be satisfied with the requirements about the data files stored and shared safely and efficiently between users.In the past decade, attribute based cryptography draws more and more attentions with its efficiency, collusion resistance ability, access policy flexibility and wide application. In this paper, on the basis of in-depth analysis of the related work, firstly according to actual distributed cloud environment, an attribute-based multi-domain proxy re-encryption scheme is proposed. In this scheme, proxy service can transform a ciphertext under one access structure into another ciphertext under a different access structure. Users in single and multi-domain can access and share datas with each other securely and high efficiently. This scheme adopt ciphertext policy attribute-based encryption algorithm with LSSS, which has a flexible access structure. The scheme is collusion resistance, and it can acquire the chosen plaintext attack security in the random oracle model under the decisional q-parallel BDHE assumption. Secondly, an attribute-based constant-size ciphertext proxy re-encryption is proposed. This scheme uses the constant-size ciphertext algorithm, which ensures that the ciphertext size is constant, not linear with the attribute numbers. This scheme can reduce the communication cost. In addition, this scheme can achieve high computational efficiency and acquire the chosen ciphertext attack security under Decisional Bilinear Diffie-Hellman(DBDH) assumption.