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 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 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 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 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.