A Robust IoT-Based Three-Factor Authentication Scheme for Cloud Computing Resistant to Session Key Exposure

Table 2

Notations.

Symbols	Description
CS	Control server
	Identity of control server
s	Master key of CS
y	Secret value of CS
	User
, ,	Identity, password, biometric of user
	Pseudoidentity of user
	Cloud server
	Identity of cloud server
	Secret key of cloud server
	Timestamps
	Session key
	Symmetric encryption/decryption algorithm with key
	The string concatenation operation
	The bitwise XOR operation
	Hash function
	Biohash function, on the basis of user’s biometric , along with a tokenized random number, it outputs a random string