  Replay attack and password attacks are serious issues in the Kerberos
authentication protocol. Many ideas have been proposed to prevent these attacks
but they increase complexity of the total Kerberos environment. In this paper
we present an improved method which prevents replay attacks and password
attacks by using Triple password scheme. Three passwords are stored on
Authentication Server and Authentication Server sends two passwords to Ticket
Granting Server (one for Application Server) by encrypting with the secret key
shared between Authentication server and Ticket Granting server.
Similarly,Ticket Granting Server sends one password to Application Server by
encrypting with the secret key shared between TGS and application server.
Meanwhile, Service-Granting-Ticket is transferred to users by encrypting it
with the password that TGS just received from AS. It helps to prevent Replay
attack.
