Secure and Efficient User Authentication Scheme Based on Password and Smart Card for Multiserver Environment

Table 1

The notations used throughout this paper.

Symbol	Description
	The registration center
	The th system user
	The th service provider
	The user ’s personal password
	Secure one-way hash functions
	The exclusive or operation
,	Random integers picked by and
,	The timestamps on sides of and
	The master secret key of
	The user ’s identity
	The server ’s identity
	The server ’s secret key
	The integer set
	The concatenation operation
,	Shared session key
	The maximum delay allowed