Privacy-preserving and Untraceable Group Data Sharing Scheme in Cloud

With the development of cloud computing, the great amount of storage data requires safe and efficient data sharing. In multiparty storage data sharing, first, the confidentiality of shared data is ensured to achieve data privacy preservation. Second, the security of stored data is ensured. That is, when stored shared data are subject to frequent access operations, the server's address sequence or access pattern is hidden. Therefore, determining how to ensure the untraceability of stored data or efficient hide the data access pattern in sharing stored data is a challenge. By leveraging proxy re-encryption and oblivious random access memory (ORAM), a privacypreserving and untraceable scheme is proposed to support multiple users in sharing data in cloud computing. On the one hand, group members and proxies use the key exchange phase to obtain keys and resist multiparty collusion if necessary. The ciphertext obtained according to the proxy re-encryption phase enables group members to implement access control and store data, thereby completing secure data sharing.