Authentication response verification using qubits and quantum channel

1 . A method for performing an authentication procedure between a verifying device located at a certain location and a responding device, wherein the verifying and responding devices are provisioned with security credentials, the method, performed by the verifying device, comprising:

generating an authentication challenge;

delivering the authentication challenge to the responding device, wherein delivering the authentication challenge to the responding device comprises:

receiving a parameter and a first signature, which is based on the parameter, from the responding device;

verifying the first signature; and

based on determining that the verification of the first signature is successful:

generating a second signature based on the received parameter and on message symbols of the authentication challenge; and

sending the authentication challenge message symbols and the second signature to the responding device;

receiving an authentication response from the responding device; and

verifying the authentication response, wherein

the authentication challenge is encoded as a sequence of qubits and delivered over a quantum communication channel between the verifying device and the responding device, and

the encoding of the authentication challenge as the sequence of qubits comprises:

encoding the authentication challenge as a sequence of photon polarisation states or coherent states of light, or

encoding the authentication challenge as a sequence of entangled states of photon pairs.

2 . The method of claim 1 , wherein

the authentication response is delivered over a non-quantum communication channel between the verifying device and the responding device.

3 . The method of claim 1 , further comprising:

verifying that a probability that the authentication challenge that is encoded as the sequence of qubits and delivered over the quantum communication channel between the verifying device and the responding device has been relayed by a third party is below a threshold value.

4 . The method of claim 1 , wherein the receiving of the parameter and the first signature from the responding device comprises receiving the parameter and the first signature over a non-quantum communication channel.

5 . The method of claim 1 , wherein the sending of the authentication challenge message symbols and the second signature to the responding device comprises sending the authentication challenge message symbols and the second signature over a non-quantum communication channel.

6 . The method of claim 1 , wherein the method comprises:

determining a probability of relay of the at least one of the authentication challenge or the authentication response.

7 . The method of claim 1 , wherein the method comprises:

encoding the authentication challenge as the sequence of entangled states of photon pairs.

8 . A method for performing an authentication procedure between a verifying device located at a certain location and a responding device, wherein the verifying and responding devices are provisioned with security credentials, the method, performed by the responding device, comprising:

receiving an authentication challenge from the verifying device;

generating an authentication response based on the authentication challenge;

encoding the authentication response as a sequence of qubits; and

delivering the encoded authentication response to the verifying device, wherein

the encoded authentication response is delivered over a quantum communication channel between the verifying device and the responding device,

encoding the authentication response as the sequence of qubits comprises:

encoding the authentication response as a sequence of photon polarisation states or coherent states of light,

delivering the encoded authentication response over the quantum communication channel to the verifying device comprises transmitting the qubits on which the authentication response is encoded to the verifying device, and

the method further comprises:

receiving a parameter and a first signature, which is based on the parameter, from the verifying device;

verifying the first signature; and

if the verification of the first signature is successful:

generating a second signature based on the received parameter and on message symbols of the authentication response; and

sending the authentication response message symbols and the second signature to the verifying device.

9 . The method of claim 8 , wherein

the authentication challenge is delivered over a non-quantum communication channel between the verifying device and the responding device.

10 . The method of claim 8 , wherein the sequence of qubits comprises a sequence of quantum states of one or more photons.

11 . The method of claim 8 , further comprising:

verifying that a probability that the authentication response that is encoded as the sequence of qubits and delivered over the quantum communication channel between the verifying device and the responding device has been relayed by a third party is below a threshold value.

12 . The method of claim 8 , wherein

the method comprises:

receiving a parameter and a first signature, which is based on the parameter, from the verifying device;

verifying the first signature; and

if the verification of the first signature is successful:

generating a second signature based on the received parameter and on message symbols of the authentication response; and

sending the authentication response message symbols and the second signature to the verifying device.

13 . The method of claim 12 , wherein the receiving of the parameter and the first signature from the verifying device comprises receiving the parameter and the first signature over a non-quantum communication channel.

14 . The method of claim 12 , wherein the sending of the authentication response message symbols and the second signature to the verifying device comprises sending the authentication response message symbols and the second signature over a non-quantum communication channel.

15 . The method of claim 12 , wherein a message symbol of the authentication response comprises at least one of:

a value of the authentication response; and

information about how the value of the authentication response was encoded as a qubit.

16 . The method of claim 15 , wherein the information about how the value was encoded as a qubit comprises at least one of:

a polarisation basis used with the authentication response value to generate a photon polarisation state;

a polarisation basis used with the authentication response value to generate a photon polarisation state of one of a pair of entangled photons;

a Bell basis used to encode the authentication response value; or

the coherent state used to encode the authentication response value.

17 . The method of claim 12 , wherein the encoding of the authentication response as the sequence of qubits comprises encoding the authentication response as a sequence of entangled states of photon pairs; and wherein encoding the authentication response as the sequence of qubits and delivering the encoded authentication response over the quantum communication channel to the verifying device comprises:

generating a sequence of entangled qubit pairs, the qubits of the entangled qubit pairs comprising photons;

transmitting one qubit from each pair to the verifying device and retaining the other qubit from each pair; and

encoding the authentication response onto retained qubits of the entangled photon pairs.

18 . The method of claim 17 , wherein the encoding of the authentication response as the sequence of qubits and delivering the encoded authentication response over the quantum communication channel to the verifying device further comprises:

transmitting the retained qubits onto which the authentication response is encoded to the verifying device.

19 . The method of claim 8 , wherein the method comprises:

determining a probability of relay of the at least one of the authentication challenge or the authentication response.

20 . A method, performed by a first device located at a certain location, for delivering a message to a second device, wherein the first and second devices are provisioned with security credentials, the method comprising:

encoding the message as a sequence of qubits;

delivering the encoded message over a quantum communication channel to the second device;

receiving a parameter and a first signature, which is based on the parameter, from the second device;

verifying the first signature; and

based on determining that the verification of the first signature is successful:

generating a second signature based on the received parameter and on message symbols of the message; and

sending the message symbols and the second signature to the second device.

21 . The method of claim 20 , wherein the receiving of the parameter and the first signature from the second device comprises receiving the parameter and the first signature over a non-quantum communication channel.

22 . The method of claim 20 , wherein the sending of the message symbols and the second signature to the second device comprises sending the message symbols and the second signature over a non-quantum communication channel.

23 . The method of claim 20 , wherein a message symbol of the message comprises at least one of:

value of the message; and

information about how the value of the message was encoded as a qubit.

24 . The method of claim 20 , wherein the encoding of the message as the sequence of qubits comprises encoding the message as a sequence of quantum states of one or more photons.

25 . The method of claim 20 , further comprising:

detecting a position of the second device, wherein

the delivering of the encoded message over the quantum communication channel to the second device comprises directing the delivery of the encoded message towards the detected position of the second device.

26 . A method for receiving a first message from a first device located at a certain location, wherein the method is performed by a second device, and wherein the first and second devices are provisioned with security credentials, the method comprising:

receiving an encoded message from the first device, wherein the encoded message comprises a sequence of qubits and is received over a quantum communication channel to the first device;

estimating the first message from the received sequence of qubits;

generating a first signature based on a parameter;

sending the first signature and the parameter to the first device;

receiving from the first device, message symbols of the first message and a second signature based on the parameter sent to the first device and on the message symbols of the first message;

verifying the second signature; and

based on determining that the verification of the second signature is successful:

comparing the estimated message from the received sequence of qubits with the received message symbols; and

based on determining that a probability of error between the estimated message and the received message symbols is below a threshold value, determining that the first message has been correctly received.

27 . The method of claim 26 , further comprising:

based on determining that the probability of the error between the estimated message and the received message symbols is above a threshold value, determining that a potential intervention by a third party has taken place during the delivery of the encoded message to the second device.

28 . The method of claim 26 , wherein sending the first signature and the parameter to the first device comprises sending the first signature and the parameter over a non-quantum communication channel.

29 . The method of claim 26 , wherein the receiving of the message symbols of the first message and the second signature from the first device comprises receiving the message symbols and the second signature over a non-quantum communication channel.

30 . A verifying device comprising processing circuitry configured to cause the verifying device to perform a method for performing an authentication procedure between the verifying device located at a certain location and a responding device, wherein the verifying and responding devices are provisioned with security credentials, the method comprising:

generating an authentication challenge;

delivering the authentication challenge to the responding device, wherein delivering the authentication challenge to the responding device comprises:

receiving a parameter and a first signature, which is based on the parameter, from the responding device;

verifying the first signature; and

based on determining that the verification of the first signature is successful:

generating a second signature based on the received parameter and on message symbols of the authentication challenge; and

sending the authentication challenge message symbols and the second signature to the responding device;

receiving an authentication response from the responding device; and

verifying the authentication response, wherein

the authentication challenge is encoded as a sequence of qubits and delivered over a quantum communication channel between the verifying device and the responding device, and

the encoding of the authentication challenge as the sequence of qubits comprises:

encoding the authentication challenge as a sequence of photon polarisation states or coherent states of light, or

encoding the authentication challenge as a sequence of entangled states of photon pairs.

31 . A responding device for performing an authentication procedure between a verifying device and the responding device, wherein the verifying device is located at a certain location, and further wherein the verifying and responding devices are provisioned with security credentials, the responding device comprising processing circuitry configured to cause the responding device to perform a method comprising:

receiving an authentication challenge from the verifying device;

generating an authentication response based on the authentication challenge;

encoding the authentication response as a sequence of qubits; and

delivering the encoded authentication response to the verifying device, wherein

the encoded authentication response is delivered over a quantum communication channel between the verifying device and the responding device,

encoding the authentication response as the sequence of qubits comprises encoding the authentication response as a sequence of photon polarisation states or coherent states of light,

delivering the encoded authentication response over the quantum communication channel to the verifying device comprises transmitting the qubits on which the authentication response is encoded to the verifying device, and

the method further comprises:

receiving a parameter and a first signature, which is based on the parameter, from the verifying device;

verifying the first signature; and

if the verification of the first signature is successful:

generating a second signature based on the received parameter and on message symbols of the authentication response; and

sending the authentication response message symbols and the second signature to the verifying device.