Cloud computing data are vulnerable to be theft illegally and tampered maliciously. To solve these problems, a Dynamic Updating Ciphertext-Policy Attribute-Based Encryption (DU-CPABE) scheme which enables both data dynamic updating and security protection was proposed. Firstly, by using linear partitioning algorithm, data information was divided into fixed size blocks. Secondly, the data blocks were encrypted by using Ciphertext-Policy Attribute-Based Encryption (CP-ABE) algorithm. Finally, based on conventional Merkle Hash Tree (MHT), an Address-MHT (A-MHT) was proposed for the operation of dynamically updating data in cloud computing. The theoretical analysis proved the security of the scheme, and the simulation in ideal channel showed that, for five updates, compared with CP-ABE method, the average time overhead of data update was decreased by 14.6%. The experimental results show that the dynamic updating of DU-CPABE scheme in cloud computng services can effectively reduce data update time and system overhead.

The authors studied the clustering mechanism in Mobile Ad Hoc Network (MANET) and proposed a maximal weighted clustering algorithm based on connected dominating set, including clustering algorithm and clustering maintenance strategy. The comprehensive performance of nodes was quantized by the weighted amount of node mobility, minimum average emissive power, and the energy consumption rate. The improved algorithm for solving connected dominating set was used for clustering the nodes, which made the higher performance nodes be the cluster heads and reduced the number of clusters. The simulation results show that the proposed algorithm is beneficial to improving the load balancing ability and enhancing the robustness and stability of the network.