e proposed external entities: STS server is responsible for strong user authentication and authorization based on PKI X.509v3 electronic certificate issued to users. Communication between the STS server and user's JAVA mobile application is SOAP based and secured by using WS-security features. After the succesful user authenti- cation and authorization, the STS server issues to the user a SAML token which will be subsequently used for the user authentication and authorization to the Web Service of the proposed m-government platform, or any other Web Service of other governmental organizations-acting as the Federation ID or Single-Sign-On instrument. The SAML token is signed by the STS server and could consist of the user role for platform's user authentication and authorization and eventually of URL of the requested governmental Web Service, found by contacting the suitable UDDI server. PKI server is responsible for issuing PKI X.509v3 electronic certificates for all users/actors in the proposed m-governmental platform (users, civil servants, administrators, servers, platforms, etc.). Since some certificate processing functions could be too heavy for mobile users, the PKI services are exposed by the XKMS (XML Key Management Specification) server which could Service Delivery Platforms register users, as well as locate or validate certificates on behalf of the mobile user. This is of particular interest in all processes that request signature veri- fication on the mobile user side. TSA server is responsible for issuing time stamps for users requests as well as for platform responses (signed m-documents). The secure JAVA mobile application communicates with all mentioned external entities, that is, it has all security functions mentioned implemented, that is, Secure JAVA mobile application sends RSTs to the STS server by using WS-Secured (WS-Signature and WS-Encryption) SOAP communication. Secure JAVA mobile applications sends digitally signed (XML signature) request for mobile governmental document to the Web Servi