A Two-Factor RSA-Based Robust Authentication System for Multiserver Environments

Table 1

Logical postulates of BAN logic.

Rule	Notation	Description
Message meaning		If principal believes is shared with and sees ,
		then believes once said .
Freshness-conjuncatenation		If believes is fresh, then believes
		the freshness of ().
Belief		If principal believes and , then believes ().
Nonce verification		If believes is fresh and the principal
		once sent , then believes that believes .
Jurisdiction		If the principal believes that has jurisdiction over and believes ,
		then believes that is true.
Session key		If believes session key is fresh and and believe , which are the
		necessary parameters of session key, then believes that (s)he shares
		session key with .