A Secure and Anonymous Two-Factor Authentication Protocol in Multiserver Environment

Table 1

Notations and abbreviations

Symbol	Description
	th user
	th remote server
	The register center
	The adversary
	The secret key of
	Identity of
	Password of
	Identity of
	The shared secret key between and
	Bitwise XOR operation
	Concatenation operation
	One-way hash function
	A common channel
	A secure channel