Today almost all big enterprise applications arebased on multi-tier Client-/Server architectures. Insuch scenarios in particular it is very hard topinpoint the layer of clients, due to the fact thatthe advancement in technology produces a lot ofdifferent potential clients. A web-based client hasbeen of no importance fifteen years ago, butcertainly is one of the most important today. This vagueness in the client tier requires a newapproach in concerns of security. The server part ofa Client-/Server architecture needs to be extended inorder to provide secure remote access of mobileclient applications. Password-based systems, as theyhappen to exist in the past, are considered to beinsufficient to meet today's security requirements.Smartcards are widely accepted, have proven to besecure and technologically mature regarding theproblems mentioned above. JavaCard(TM) and the OpenCardFramework enable the developer to program with ahigh-level language on both the smartcard and theterminal application level.