A Secure and Lightweight Three-Factor Remote User Authentication Protocol for Future IoT Applications

Table 1

Symbols used.

Notation	Description
	Remote user
	Identity of the user
	The user password
	Extracting user iris
,	Random numbers generated by the user
	The fingerprint of the user
	Feature extraction level 3
	IoT sensing nodes
	The shared secret key of the IoT devices, generated by
	The trusted gateway node
	A secret key generated by the gateway
	A secret key generated for the user
, , , ,	Timestamps
	Shared session key
	XOR operation
	Concatenation operation
	One-way hash function