The Security Analysis of Data Re-Encryption Model in Cloud Services

Cloud computing provides both opportunities to develop more services as well as significant risks for greater exposure to data privacy problem when users outsource sensitive data for sharing on cloud servers. Re-encryption scheme offers a solution to this issue, which allows the data owner to delegate most of the computation tasks to untrusted cloud servers providers without disclosing the underlying data contents. However, collusion attack by untrusted cloud service providers and legal data users is still a key threat to data privacy in cloud data service. In this paper, we study on the collusion attack issue by analyzing re-encryption model and classic encryption methods, and indicate how to choose encryption algorithm to against collusion attack in re-encryption model. Extended experiments show that our study is provably secure under existing cloud environment.