Improved authentication algorithm for UMTS

Authentication process of user in mobile networks is an important issue. Previous standard of telecommunication Global System for Mobile Communication (GSM) has many security weaknesses. Under Third Generation Partnership Project(3GPP), new standard Universal Mobile Telecommunication System is developed. Which removes the security weaknesses of previous standards. However one security loop hole has been revealed in UMTS. It is the sending of International Mobile Subscriber Identity (IMSI) in plain text over the air interface. In this paper we introduce a security algorithm named as Airam, whose name is derived from developers of this algorithm. It resolves the problem of sending IMSI in plain text over the air interface by implementing asymmetric/symmetric cryptography techniques. We have presented simulation results of Airam algorithm that show how effciently Airam algorithm performs the user authentication process and its effectiveness against replay and imposition attacks.