In recent times the usage of smart phones has significantly increased. Businesses are transforming to make more out of smart phones. As a consequence, there is an increasing demand to have more and more mobile applications. Among other areas, mobile applications are also being used to make financial transactions. Applications used for financial transactions need to be more reliable and have end-to-end security. To implement security we heavily depend on cryptography and the heart of cryptography is the keys which are used in cryptographic processes (encryption/decryption). Therefore, it is essential not only to protect, but also to properly manage these keys, so that a robust and secure system can be achieved. This research work provides a complete implementation of symmetric key management for mobile phone applications with a focus on financial data using a key hierarchy approach. We have developed a key management system which allows smart phones to download the cryptographic key hierarchy. This key hierarchy is used to encrypt and decrypt financial data, such as PIN and other transaction information. Using this application (key management system), we can achieve an end-to-end security between client (mobile phones) and payment server (banking server). This research work presents implementation of key management system for Android OS only.