Cryptanalysis and Security Enhancement of Three Authentication Schemes in Wireless Sensor Networks

Table 1

Notations and abbreviations.

Symbol	Description
	user
	remote sensor node
GWN	gateway node
	malicious attacker
,	identity of and
	password of
	the secret key of gateway node GWN
	a smart card
	the XOR operation
	the concatenation operation
	one-way hash function
	the public channel
	the secure channel