A method for performing a secure key relay of an encryption key, K enc , provided by an initial node, KN 0 , and used by an encoding unit (ENC) of a first data transceiver for encoding plain data, P data , to provide encrypted cipher data, C data , transported via a data transport link ,DTL, to a decoding unit (DEC) of a second data transceiver which decodes the transported cipher data, C data , using the relayed encryption key, K enc , provided by a terminal node, KN N , as a decoding key to retrieve the plain data, P data , wherein the relay of the encryption key, K enc , from the initial node, KN 0 , to the terminal node, KN N , is performed by means of intermediate relay nodes, KN 1 , KN 2 ...KN N-1 , and comprises the steps of: - sharing QKD-keys, K, between the nodes via secure quantum channels, QCH, of a quantum key distribution network, QKDN; - performing encryption of shared QKD-keys, K, at the initial node, KN 0 , and at each intermediate relay node, KN 1 , KN 2 ...KN N-1 , and blinding them with a blinding value, S i , of the respective node to provide an encrypted cipher key, CK i , by the initial node, KN 0 , and by each intermediate relay node, KN 1 , KN 2 ...KN N-1 , wherein the shared QKD-keys are encrypted by performing an XOR-operation on the QKD-keys at the respective intermediate relay node, wherein the encryption key, K enc , is encrypted by performing an XOR-operation on the encryption key, K enc , and a QKD-key, K 1 , at the initial node, KN 0 ; - transmitting the encrypted cipher keys, CK i , of the initial node, KN 0 , and of each of the intermediate relay nodes, KN 1 ,KN 2 ...KN N-1 , to the terminal node, KN N ; and - performing by the terminal node, KN N , logic operations on blinding values, S i , on the basis of the encrypted cipher keys, CK i , received by the terminal node, KN N , from the initial node, KN 0 , and received from each of the intermediate relay nodes, KN 1 , KN 2 ...KN N-1 , to provide the encryption key, K enc , used by the decoding unit (DEC) of the second data transceiver as a decoding key to retrieve the plain data, P data , wherein the logic operations performed by the terminal node, KN N , to provide the encryption key, K enc , on the basis of the blinding values, S i , and the received encrypted cipher keys, CK i , comprise XOR-operations. - sharing QKD-keys, K, between the nodes via secure quantum channels, QCH, of a quantum key distribution network, QKDN; - performing encryption of shared QKD-keys, K, at the initial node, KN 0 , and at each intermediate relay node, KN 1 , KN 2 ...KN N-1 , and blinding them with a blinding value, S i , of the respective node to provide an encrypted cipher key, CK i , by the initial node, KN 0 , and by each intermediate relay node, KN 1 , KN 2 ...KN N-1 , wherein the shared QKD-keys are encrypted by performing an XOR-operation on the QKD-keys at the respective intermediate relay node, wherein the encryption key, K enc , is encrypted by performing an XOR-operation on the encryption key, K enc , and a QKD-key, K 1 , at the initial node, KN 0 ; - transmitting the encrypted cipher keys, CK i , of the initial node, KN 0 , and of each of the intermediate relay nodes, KN 1 ,KN 2 ...KN N-1 , to the terminal node, KN N ; and - performing by the terminal node, KN N , logic operations on blinding values, S i , on the basis of the encrypted cipher keys, CK i , received by the terminal node, KN N , from the initial node, KN 0 , and received from each of the intermediate relay nodes, KN 1 , KN 2 ...KN N-1 , to provide the encryption key, K enc , used by the decoding unit (DEC) of the second data transceiver as a decoding key to retrieve the plain data, P data , wherein the logic operations performed by the terminal node, KN N , to provide the encryption key, K enc , on the basis of the blinding values, S i , and the received encrypted cipher keys, CK i , comprise XOR-operations. <EOS>