Security is becoming vital in today's open insecure Internet. While popular Internet enabled mobile devices are spreading widely, the security of such platforms is not maturely addressed. This research extends the popular Kerberos authentication protocol to run on mobile phones and builds a novel Kerberos Secure Phone Messenger (KSPM) on top of the protocol. Moreover, the Kerberos network authentication protocol provides user authentication and message privacy with the convenience of secret key cryptography. Such an advantage in mobile phones helps reduce the computational burden and power consumption if compared with public key cryptography. KSPM achieves high standards in terms of security, performance and power consumption. This thesis explains Kerberos authentication and illustrates the software implementation of the protocol and KSPM. Furthermore, it analyzes the performance and power consumption required by KSPM.