A method for controlling a quantum key distribution between a first quantum node and a second quantum node over longer distances of a quantum connection including at least one intermediate untrusted quantum node, each quantum node (110, 120, 150) comprising at least one quantum key distribution module (112, 122, 152) and at least one key management system (113, 123, 153), wherein the at least one intermediate untrusted quantum node is located on the quantum connection between the first quantum node and the second quantum node, the method comprising at least: a) providing, at each of the at least one intermediate untrusted quantum node, a mechanical robust containment surrounding the at least one quantum key distribution module and the at least one key management system, the mechanical robust containment being configured to prevent an instant physical access to the at least one quantum key distribution module and the at least one key management system, b) supplying, at each of the at least one intermediate untrusted quantum node, the mechanical robust containment with an input unit for keying in a respective security code which is used to authorize an opening of a bonnet of the mechanical robust containment to access the at least one quantum key distribution module and the at least one key management system of the respective intermediate untrusted quantum node, c) generating the respective security code using cryptographic key material which has been withhold for own use from a part of self-generated key material between the respective one of the at least one intermediate untrusted quantum node and the respective first or second quantum node during quantum key distribution and which is to be made available exclusively to at least one of the first quantum node and the second quantum node asking for access, and the respective one of the at least one intermediate untrusted quantum node wherein generating the respective security code is initiated at the first quantum node or at the second quantum node each of which representing a respective customer. a) providing, at each of the at least one intermediate untrusted quantum node, a mechanical robust containment surrounding the at least one quantum key distribution module and the at least one key management system, the mechanical robust containment being configured to prevent an instant physical access to the at least one quantum key distribution module and the at least one key management system, b) supplying, at each of the at least one intermediate untrusted quantum node, the mechanical robust containment with an input unit for keying in a respective security code which is used to authorize an opening of a bonnet of the mechanical robust containment to access the at least one quantum key distribution module and the at least one key management system of the respective intermediate untrusted quantum node, c) generating the respective security code using cryptographic key material which has been withhold for own use from a part of self-generated key material between the respective one of the at least one intermediate untrusted quantum node and the respective first or second quantum node during quantum key distribution and which is to be made available exclusively to at least one of the first quantum node and the second quantum node asking for access, and the respective one of the at least one intermediate untrusted quantum node wherein generating the respective security code is initiated at the first quantum node or at the second quantum node each of which representing a respective customer.