One aspect relates to a process and associated device that provides a private key of an asymmetric key pair in a key device. The dishwashing container communicates with the dishwashing compartment to receive through a collecting plate liquid that has been discharged by the spray means. During injection, a quantity related to a feed volume flow of the injectable material is monitored. Preferably, at least part of an inner surface of the capillary extends in the moving direction of the sample liquid and is a water-insoluble high-wettability region having a wettability of no less than 57 mNm.