A method for operating a Continuous Variable-Quantum Key Distribution, CV-QKD, system comprising a transmitter CV-QKD device 'A' and a receiver CV-QKD device 'B', wherein the method comprises: storing and transmitting, by the transmitter CV-QKD device 'A', a quantum signal over a communication channel, wherein the quantum signal has a first phase, a first central frequency, a first pulse shape, and a first bandwidth; receiving, by the receiver CV-QKD device 'B', the quantum signal via the communication channel and via a reception band of the receiver CV-QKD device 'B', the reception band having a second central frequency and a second bandwidth, wherein the second central frequency is offset from the first central frequency by a frequency shift caused by the communication channel, wherein the received quantum signal has a second phase and a second pulse shape, wherein the second phase is offset from the first phase by a phase shift caused by the communication channel and the second pulse shape is offset from the first pulse shape by a delay caused by the communication channel; determining, by the receiver CV-QKD device 'B', a quantum communication channel based on the phase shift, the frequency shift, the delay, and a third bandwidth resulting from an overlap between the first bandwidth around the first central frequency and the second bandwidth around the second central frequency; communicating, by the receiver CV-QKD device 'B', the determined quantum communication channel to the transmitter CV-QKD device 'A' over an authenticated communication channel; obtaining, by the transmitter CV-QKD device 'A', a modified quantum signal by modifying the stored quantum signal based on the determined quantum communication channel; and generating, by the transmitter CV-QKD device 'A' and the receiver CV-QKD device 'B', a secret key using the modified quantum signal and the received quantum signal. storing and transmitting, by the transmitter CV-QKD device 'A', a quantum signal over a communication channel, wherein the quantum signal has a first phase, a first central frequency, a first pulse shape, and a first bandwidth; receiving, by the receiver CV-QKD device 'B', the quantum signal via the communication channel and via a reception band of the receiver CV-QKD device 'B', the reception band having a second central frequency and a second bandwidth, wherein the second central frequency is offset from the first central frequency by a frequency shift caused by the communication channel, wherein the received quantum signal has a second phase and a second pulse shape, wherein the second phase is offset from the first phase by a phase shift caused by the communication channel and the second pulse shape is offset from the first pulse shape by a delay caused by the communication channel; determining, by the receiver CV-QKD device 'B', a quantum communication channel based on the phase shift, the frequency shift, the delay, and a third bandwidth resulting from an overlap between the first bandwidth around the first central frequency and the second bandwidth around the second central frequency; communicating, by the receiver CV-QKD device 'B', the determined quantum communication channel to the transmitter CV-QKD device 'A' over an authenticated communication channel; obtaining, by the transmitter CV-QKD device 'A', a modified quantum signal by modifying the stored quantum signal based on the determined quantum communication channel; and generating, by the transmitter CV-QKD device 'A' and the receiver CV-QKD device 'B', a secret key using the modified quantum signal and the received quantum signal.