A Blockchain-Based Hierarchical Authentication Scheme for Multiserver Architecture

Table 1

Definition of notations.

Notation	Definition
	Prime numbers
	A finite field of order
	An elliptic curve over the finite field
	An additive group consisting of points on
	A generator of the group with order
	user
	server
	user’s identity
	server’s identity
	user’s password
	user’s biometrics information
	user’s biometrics key
	Access permission level
,	user’s public-private key pair
,	application server’s public-private key pair
,	permission server’s public-private key pair
	Encoding and as strings from which the constituent objects are easily recoverable
	Encoding and as a binary bit string for an XOR operation
	Operation of assigning to an element of chosen at random
	Two secure hash functions
,	The range of the output of the hash functions
	Adversary in the security model
	Challenger in the security model
	session between user and server