Research On Attribute-based Proxy Re-Encryption Algorithm

As an emergent service mode based on Internet in recent years, cloud computing is gradually spread and popularized. It combines internet resources in different regions and types to meet the requirements of storing and processing vast data very well. The cloud mode, which can greatly improve resources utilization and potentially lowers the use cost of users, has obtained an extensive sustainment and been widely used. The cloud storage service mode, however, also brings new security hazards, one of which is how to assure the security of data storage as well as to achieve fine-grained access control and efficient sharing.Attribute-based cryptography is an attractive research topic in recent years. It provides fine-grained and non-interactive access control of encrypted data and has wide application prospects. And the proxy re-encryption is used in the cloud to transform ciphertext, thus reducing the burden of the client and realizing efficient data sharing. In this background, attribute-based proxy re-encryption (ABPRE) scheme is proposed. In an ABPRE system, user A called delegator has rights to decrypt and sends a semi-trusted proxy a re-key. Then the proxy can use the received re-key to translate the original ciphertext to the re-encryption ciphertext which user B called delegatee can decrypt by his own secret key. What is more, in the above process, the proxy can not get any information about users’ secret key or the plaintext.But unfortunately, the existing ABPRE schemes have disadvantages in terms of security and efficiency. On the above-mentioned aspects, the paper proposes a new ciphertext-policy ABPRE scheme which can be proved to be adaptive security to resist the adversary with a stronger aggressivity and, at the same time, the encryptor has the ability to control the original ciphertext can be re-encrypted or not. Our scheme, which is more suitable for practical application, has obvious advantages in computation efficiency and performance when compared with the previous ABPRE schemes. The new scheme can be used in distributes file system, cloud storage environment, electronic medical services and other scenes, to realize the secure storage and efficient access control of data in public servers.