Method for access to an operating system, removable memory medium and use of a removable memory medium

A computer arrangement comprising:

• a first computer comprising a USB interface, a network interface and a processor configured to execute an auxiliary operating system;
• a second computer comprising at least one processor configured to execute a main operating system, wherein the second computer runs a virtualization system to provide virtual computer workstations, and the main operating system is executed on a virtual computer workstation;
• a removable storage medium connected to the USB interface of the first computer, the removable storage medium comprising at least one write protected memory area comprising an auxiliary operating system and access software that sets up a data link between the first computer and the second computer;
• and
• the removable storage medium further comprising 1) at least one memory area not write protected that stores user data and/or temporary data and/or settings data from the auxiliary operating system;
• and 2) at least one microcontroller that controls access operations by the first computer to the at least one write protected memory area and the at least one memory area not write protected, the microcontroller comprising an encryption unit configured to encode or decode the data link protected by encryption;
• wherein the first computer loads the auxiliary operating, system from the write protected memory area of the removable storage medium upon start of the first computer;
• the first computer executes the auxiliary operating system;
• the first computer loads the access software from the write protected memory area of the removable storage medium;
• the first computer executes the loaded access software on the first computer under control of the auxiliary operating system;
• the first computer sets up a first connection to a third computer, arranged in a demilitarized zone, having a predetermined address stored on the removable storage medium;
• the first computer transmits an explicit identifier for the removable storage medium to the third computer;
• the third computer checks the explicit identifier using a set of valid identifiers;
• the third computer transmits access data for setting up an IP tunnel between the second computer and the first computer to the first computer if the checking of the explicit identifier was successful;
• the first computer sets up a secure second connection between the first computer and the second computer via the IP tunnel by using the transmitted access data without further involving the third computer, the second computer being arranged in a protected zone;
• the second computer requests the input of a user name and a password to grant access to the virtual computer workstation;
• and
• the access software provides access to the virtual computer workstation of the virtualization system, on which the main operating system is executed.