A computer system includes a first storage area accessible by an operating system and a second storage area accessible by authorized functions only. According to some embodiments of the invention at least one protected storage area is implemented into the second storage area, wherein the operating system installs at least one secret key and/or at least one customized processing function into regions of the at least one protected storage area, wherein the operating system transfers data and/or parameters to process into regions of the at least one protected storage area, wherein the operating system selects one of the customized processing functions to execute, wherein the selected customized processing function is executed and accesses storage regions of the at least one protected storage area to process the data and/or parameters, and wherein resulting process data is read from the at least one protected storage area.