time stamp- ing and XKMS. In this sense, main contributions of this study are (1) proposal of a possible secure m-government model based on JAVA mobile application and SOA- based m-government platform, (2) usage of secure JAVA mobile application in which all modern security techniques are implemented (XML security, WS-security, SAML, time stamping, PKI, XKMS), (3) usage of SOA-based request-response m-govern- ment platform Web Service instead of session-based Web application platform which is more suitable for usage of secure mobile application, and (4) usage of XKMS service which is more suitable for mobile PKI system since it outsources complex operations such as PKI validation services to the external entity-the XKMS server, compared to usages of other techniques. The work presented and examples described are included in the general framework of the EU IST FP6 SWEB project. Acknowledgments This work was carried out in the context of the IST international cooperation proj- ect SWEB (044979). This study is based on the work performed within the context of this project and the authors would like to acknowledge all SWEB partners. Service Delivery Platforms Disclaimer This research outlined in this chapter has been undertaken with the financial assis- tance of the European Community. The views expressed herein are those of SWEB Consortium and therefore can no way be taken to reflect the official opinion of the European Commission. The information in this document is provided as is and no guarantee or warranty is given to state that the information is fit for any particular purpose. The user therefore uses the information at their sole risk and liability. References 1. SWEB Project Homepage. http://www.sweb-project.org 2. Kolsi, O. and Virtanen, T. MIDP 2.0 security enhancements, Proceedings of the 37th Hawaii International Conference on System Sciences, Big Island, HI, USA, 2004. 3. Papastergiou, S., Karantjias, A., Polemi, D., and Markovic, M. A secure mobile frame- work for m-services, The Third International Con