Is there a more simple solution for updating the CRYPTO-BOX - without requiring any data (Transaction Key) from the customer first?

The SxFormat.exe command line tool allows you to create a small tool which performs an update of the CRYPTO-BOX when started on the end-user's computer. More details can be found in the RUMS Application Notes, chapter 4.

Important:
With RUMS and RU_Tool, the Activation Code can be executed only on the CRYPTO-BOX which was used to issue the Transaction Key before. When using SxFormat, by default you have no control on which CRYPTO-BOX it might be executed.
Therefore we strongly recommend that you consider using check conditions before updating the CRYPTO-BOX to prevent misuse (otherwise customers may use SxFormat to update multiple CRYPTO-BOXes). This can be defined in the XML file for SmrxProg using the extended script format. See SmrxProg readme file, Appendix A for further information.