The rst potential attack during login procedure arises from the lack of mutual au-thentication between the user and the system. For example, an attacker may place a program at the access point that emulates the login prompt sequence, therefore, the name and password can be captured. Such kind of attacks are referred to as Trojan horses. Describe one approach to counter such attacks and explain how this approach helps users to identify if a Trojan horse attack is underway.