1. Center for Security, Theory and Algorithmic Research; International Institute of Information Technology; Hyderabad 500 032 India
2. Department of Mathematics; Chaudhary Charan Singh University; Meerut 250 005h Uttar Prades India
3. School of Computer Science and Engineering; Hunan University of Science and Technology; Xiangtan 411201 China
4. Department of Computer Science and Engineering; Xiamen Institute of Technology, Huaqiao University; Xiamen 361021 China