Funding for this research was provided by:
The National Science and Technology Major Project (2017YFB0803001)
The National Natural Science Foundation of China (61502048)
The National “242” Information Security Program (2015A136)
Article History
Received: 1 December 2017
Revised: 25 January 2018
Accepted: 12 February 2018
First Online: 2 March 2018