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

Table 2

The capacities of the adversary.

	can intercept, modify, delete, and resend the messages between the users and the servers over the open channel.
	can enumerate all the items in the password space and identity space simultaneously.
	When cryptanalyzing a scheme, can know the identity of .
	knows the identity of .
	can learn the password of by a malicious card reader, or extract the parameters from the smart, but cannot achieve both.
	When evaluating forward secrecy, knows the long term secret key of the register center.