Abstract: The confidentiality of data is a difficult problem in a cloud computing environment. The DAC technique (Dynamic Access Control) based on encrypted data is an important way to solve this problem. In the current access control techniques based on encrypted data, the high-security requirement of data and frequent policy updates lead to the high cost of owner right update which seriously restricts the flexibility of access control. A DCA method based on CACDP encrypted data is proposed. The selective encryption model is built. In the model, a key derivation diagram is generated to distribute the key. In the case of ensuring the confidentiality of cloud computing access control, the key is less in the system. The proposed CACDP scheme includes the key management mechanism based on the binary Trie tree. Based on this, the ELGamal-based proxy re-encryption mechanism and double layer encryption strategy are used to transfer the partial spending of the key and data update to the cloud to ease the DO authority management burden and increase the efficiency of DO. Then, the DCA method of encrypted data in cloud computing environment is researched. Experimental results show that our proposed method can effectively improve the flexibility of encrypted data access control.

Key words: cloud computing environment, encrypted data, dynamic access, data control