A Lightweight Privacy Protection User Authentication and Key Agreement Scheme Tailored for the Internet of Things Environment: LightPriAuth

Table 7

The cost of hash operations in the registration phase.

Phase	User registration				Sensor registration
Entity	User	Gateway	Total	Ratio	Sensor	Gateway	Total	Ratio
Wu et al. [9]	2	3	5	2.5	0	1	1	1/7
Wu et al. [14]	2	3	5	2.5	0	1	1	1/7
Chang and Le [11]	1	2	3	1.5	0	1	1	1/7
Chen et al. [1]	1	1	2	1	3	4	7	1
LightPriAuth	1	2	3	1.5	0	1	1	1/7