Sammendrag
This paper deals with security aspects of the web-portal Altinn and shows how these aspects can be formalized and modeled in the high level programming language, Maude. Thereafter there will be given examples of how this model can be used for automatic analysis, in such a way that it can reveal faults or making the design choices become trustworthy. The model will include network layers and give a realistic representation of Altinn on an abstract level. The layers consist of TCP and SSL and on top of these there are modeled client authentication with password and authorization mechanisms.