Cryptanalysis and Security Improvement of Two Authentication Schemes for Healthcare Systems Using Wireless Medical Sensor Networks

Table 1

Notations.

Notation	Description
Ui	i^th user
RA	Registration agent
GWN	Gateway node
Sj	j^th sensor node
IDi	The identity of Ui
SIDj	The identity of Sj
PWi	The password of Ui
BIOi	Ui’s biometrics
⊕	The bitwise XOR operation
||	The concatenation operation
⟹	The secure channel
⟶	The public channel
h()	A secure one-way hash function
H()	Bio-hash function
Ek()/Dk()	The symmetric encryption/decryption function with key k
Ti	The current timestamp, i = 1, 2, …
MD	Mobile device of Ui
MIDi	Temporary identity of Ui
	The identity of GWN
NCk0	Serial number in GWN side
NCk	Serial number in Sj side