Research On Outsourcing The Decryption And Re-encryption Of Abe Ciphertext In Cloud Computing

Cloud computing is a kind of mode that unified management and dispatch large computingresources connected by the network, and it compose a computational resources pool to providecomputing and storage services to users. In the era of high performance, large data, cloud com-puting has attracted much attention. While the cloud providing services to users, the securityproblem is the biggest concerns for the cloud computing, especially public cloud security is-sues. With the mature and promotion of cloud computing technology, many users will put theirvast amounts of data in the cloud server. By outsourcing their data in the cloud server, user-s can obtain high quality data storage and processing services. With the help of the powerfulcomputing ability of cloud server, the users could finish data processing in a cloud environment.But the cloud is honest-but-curious server, in the process of calculation, it need to protect thesecurity of plaintext and secret key. This paper mainly has the following two jobs:1. Outsourcing the decryption of multi-authority ABE ciphertexts. Introduce the multi-authority ABE scheme of Chase. We give outsourcing the decryption of ABE ciphertextsschemes of Green, Hohenberger and Waters in detail. But in their schemes, it deal with s-ingle authority ABE ciphertext. By means of Waters and Chase’s schemes, we apply linearmulti-secret sharing schemes to design the outsourcing decryption of multi-authority ABE ci-phertext schemes. It can resolve the problem that the attributes managed by multi-authority. Weanalyze the security and efficiency, and then extend our schemes to RCCA security.2. Outsourcing the re-encryption of ABE ciphertext. Mambo first proposed the conceptof proxy re-encryption (PRE). In this paper, we apply his thought to ABE ciphertext that theaccess structure is matrix, and put forward outsourcing the re-encryption of ABE ciphertext. Itrealizes authorized decryption for user. The user can decrypt the ciphertext does not have timeto deal with ciphertext, he may authorize other person to handle. With the help of the cloudserver, it converts the second level cipher to first level cipher. The cloud server can not get theinformation of user’s secret key. It not only inherits some properties of PRE, the encryptor canalso decide whether the ciphertext can be re-encrypted.