1. Center for Security, Theory and Algorithmic Research; International Institute of Information Technology; Hyderabad 500 032 India
2. Department of Mathematics; Ch. Charan Singh University; Meerut 250 005 Uttar Pradesh India
3. Department of Mathematics; Indian Institute of Technology; Kharagpur 721 302 India
4. School of Computer Science and Engineering; Hunan University of Science and Technology; Xiangtan 411201 China
5. Department of Computer Science and Engineering; Xiamen Institute of Technology; Xiamen 361021 China
6. Fujian Provincial Key Laboratory of Network Security and Cryptology, The School of Mathematics and Computer Science; Fujian Normal University; Fuzhou Fujian China
7. The State Key Laboratory of Cryptology; Beijing China