Data security is an important issue in current scenario of banking financial operation especially with transaction of secure and confidential data. It must be send with high security at the time of communication. In this paper the authors will discuss various types of encryption methods and standards which are used in secure banking data transmissions to make more data security. Especially here they discuss the communication security methods used between auto teller machine and bank server banking financial operations, when they transmit data from an Auto Teller Machine (ATM) to bank server it must send in encrypted form so that an unauthorized user cannot access the secure information directly at the time of data communication.