Method and system for creating a quantum secured encryption key

1. A method, comprising:

in a preparation step:

a first quantum key distribution (QKD) device at a first location and a second QKD device at a second location distant from the first location together create a quantum secured key wherein the first QKD device communicates with at least one common intermediate quantum node via a first quantum channel and the second QKD device communicates with the at least one common intermediate quantum node via a second quantum channel, and wherein the first and second QKD devices communicate via an authenticated digital distillation channel separate from the first and second quantum channels for transmitting and receiving control information; and

a first encryption device at the first location and a second encryption device at the second location together create a symmetrically encrypted channel between the first encryption device at the first location and the second encryption device at the second location using the quantum secured key; and

in a key agreement step, a first key agreement device at the first location and a second key agreement device at the second location together create an encryption key using an asymmetric key exchange procedure, wherein key material for creating the encryption key is exchanged between the first key agreement device and the second key agreement device via the symmetrically encrypted channel.

2. The method according to claim 1 , wherein the encryption key is provided to at least one first application at the first location and to at least one second application at the second location.

3. The method according to claim 1 , wherein the symmetrically encrypted channel is created using the Advanced Encryption Standard (AES).

4. The method according to claim 1 , wherein the asymmetric key exchange procedure is based on post-quantum symmetric cryptography (PQC).

5. The method according to claim 1 , wherein the asymmetric key exchange procedure is based on Diffie—Hellman key exchange (DH), Diffie Hellman Elliptic Curve (DHEC), or Rivest—Shamir—Adleman (RSA).

6. The method according to claim 1 , wherein the first key agreement device and the second key agreement device are configured to automatically exchange the key material between the first key agreement device and the second key agreement device via the symmetrically encrypted channel.

7. The method according to claim 1 , wherein the first key agreement device and the second key agreement device are provided with a signalling signal to initiate the exchange of initiating that the key material between the first key agreement device and the second key agreement device via the symmetrically encrypted channel.

8. An encryption system, comprising:

at least one intermediate quantum node;

a first quantum key distribution (QKD) device at a first location; and

a second QKD device at a second location;

a first encryption device at the first location:

a second encryption device at the second location; and

a first key agreement device at the first location; and

a second key agreement device at the second location;

wherein the first QKD device and the second QKD device are configured to together create a quantum secured key;

wherein the first QKD device is configured to communicate with at least one common intermediate quantum node via a first quantum channel;

wherein the second QKD device is configured to communicate with the at least one common intermediate quantum node via a second quantum channel;

wherein the first and second QKD devices communicate via an authenticated digital distillation channel separate from the first and second quantum channels for transmitting and receiving control information;

wherein the first and second encryption devices are configured to create a symmetrically encrypted channel between the first and second encryption devices using the quantum secured key;

wherein the first and second key agreement devices are configured to together create, in a key agreement step, an encryption key using an asymmetric key exchange procedure;

wherein the first and second key agreement devices are configured to exchange key material for creating the encryption key via the symmetrically encrypted channel.

9. The system according to claim 8 , wherein the first key agreement device is further configured to provide the encryption key to at least one first application at the first location, and the second key agreement device is further configured to provide the encryption key to at least one second application at the second location.

10. The system according to claim 8 , wherein the symmetrically encrypted channel is created using the Advanced Encryption Standard (AES).

11. The system according to claim 8 , wherein the asymmetric key exchange procedure is based on post-quantum symmetric cryptography (PQC).

12. The system according to claim 8 , wherein the asymmetric key exchange procedure is based on Diffie—Hellman key exchange (DH), Diffie Hellman Elliptic Curve (DHEC), or Rivest—Shamir—Adleman (RSA).

13. The system according to claim 8 , wherein the first key agreement device and the second key agreement device are configured to automatically exchange the key material between the first key agreement device and the second key agreement device via the symmetrically encrypted channel.

14. The system according to claim 8 , wherein the first QKD device and the second QKD device are configured to provide the first key agreement device and the second key agreement device, respectively, with a signalling signal to initiate the exchange of the key material between the first key agreement device and the second key agreement device via the symmetrically encrypted channel.