Recently, wireless technologies in the form of mobile phones have become a pervasive part of our everyday live due to their convenience, light weight and lower transaction cost. However, performing payments using mobile phones have given a rise to security issues because of their limited resources and Open Air communication channel. Therefore, a secure mobile phone communication system has become a serious and crucial issue. This paper proposes a new security enhancement on smart phone using the Limitedused Key generation technique based on the KSL protocol. Our implementation adapts and compares two popular PKC systems (RSA and ECC) as a design solution for mobile phone payments security enhancement.