Configuring a target device

1. A method for configuring a target device, the method performed by a user device and comprising:

transmitting a configuration request message to the target device, the configuration request message comprising a configuration request and a request signature, wherein the configuration request message includes a unique session identifier, and wherein the request signature is based on the configuration request and a secret key of the user device;

receiving a configuration response message from the target device, the configuration response message comprising a configuration response and a response signature, wherein the response signature is a cryptographic signature of a combination including the configuration response and the request signature, the response signature derived by using the secret key of the target device in a cryptographic signing operation;

verifying the response signature to determine whether the configuration response message is valid, based on the configuration response, the request signature and a public key for the target device; and

transmitting a configuration commit message to the target device only when the configuration response message is valid, the configuration commit message comprising a configuration commit indicator and a commit signature, wherein the commit signature is a cryptographic signature of a combination including the configuration commit indicator and the response signature, and is generated based on the secret key of the user device;

wherein the user device stores the messages, including the signatures.

2. The method according to claim 1 , further comprising: receiving a configuration acknowledgement message from the target device, the configuration acknowledgement message comprising a configuration acknowledgement and an acknowledgement signature, wherein the acknowledgement signature is based on the configuration acknowledgement and the commit signature; and

verifying the acknowledgement signature to determine whether configuration acknowledgement message is valid, based on the configuration acknowledgement, the commit signature and a public key for the target device.

3. The method according to claim 1 , wherein each signature is applied to a hash value of the input data for the signature.

4. The method according to claim 1 , wherein all messages comprise the same single remote procedure call, RPC, identifier.

5. A user device for configuring a target device, the user device comprising:

a processor; and

a memory storing instructions that, when executed by the processor, cause the user device to:

transmit a configuration request message to the target device, the configuration request message comprising a configuration request and a request signature, wherein the configuration request message includes a unique session identifier, and wherein the request signature is based on the configuration request and a secret key of the user device;

receive a configuration response message from the target device, the configuration response message comprising a configuration response and a response signature, wherein the response signature is a cryptographic signature of a combination including the configuration response and the request signature, the response signature derived by using the secret key of the target device in a cryptographic signing operation;

verify the response signature to determine whether the configuration response message is valid, based on the configuration response, the request signature and a public key for the target device; and

transmit a configuration commit message to the target device only when the configuration response message is valid, the configuration commit message comprising a configuration commit indicator and a commit signature, wherein the commit signature is a cryptographic signature of a combination including the configuration commit indicator and the response signature, and is generated based on the secret key of the user device;

wherein the user device is configured to store the messages, including the signatures.

6. A non-transitory computer readable medium storing a computer program for configuring a target device, the computer program comprising computer program code which, when run on a user device causes the user device to:

transmit a configuration request message to the target device, the configuration request message comprising a configuration request and a request signature, wherein the configuration request message includes a unique session identifier, and wherein the request signature is based on the configuration request and a secret key of the user device;

receive a configuration response message from the target device, the configuration response message comprising a configuration response and a response signature, wherein the response signature is a cryptographic signature of a combination including the configuration response and the request signature, the response signature derived by using the secret key of the target device in a cryptographic signing operation;

verify the response signature to determine whether the configuration response message is valid, based on the configuration response, the request signature and a public key for the target device; and

transmit a configuration commit message to the target device only when the configuration response message is valid, the configuration commit message comprising a configuration commit indicator and a commit signature, wherein the commit signature is a cryptographic signature of a combination including the configuration commit indicator and the response signature, and is generated based on the secret key of the user device;

wherein the user device is configured to store the messages, including the signatures.

7. A method for configuring a target device, the method performed by the target device and comprising:

receiving a configuration request message from a user device, the configuration request message comprising a configuration request and a request signature, wherein the configuration request includes a unique session identifier, and wherein the request signature is based on the configuration request and a secret key of the user device;

verifying the request signature to determine whether configuration request message is valid, based on the configuration request and a public key for the user device;

transmitting a configuration response message to the user device only when the configuration request message is valid, the configuration response message comprising a configuration response and a response signature, wherein the response signature is a cryptographic signature of a combination including the configuration response and the request signature, the response signature derived by using the secret key of the target device in a cryptographic signing operation;

receiving a configuration commit message from the user device only when the configuration request message is valid, the configuration commit message comprising a configuration commit indicator and a commit signature, wherein the commit signature is a cryptographic signature of a combination including the configuration commit indicator and the response signature, and is generated based on the secret key of the user device; and

verifying the commit signature to determine whether configuration commit message is valid, based on the configuration commit indicator, the response signature and a public key for the user device;

wherein the target device stores the messages, including the signatures.

8. The method according to claim 7 , further comprising:

applying configuration for the target device in accordance with the configuration request; and

transmitting a configuration acknowledgement message to the user device, the configuration acknowledgement message comprising a configuration acknowledgement and an acknowledgement signature, wherein the acknowledgement signature is based on the configuration acknowledgement and the configuration commit signature.

9. The method according to claim 8 , wherein transmitting a configuration acknowledgement message comprises generating the acknowledgement signature based on a secret key of the target device.

10. The method according to claim 7 , wherein each signature is applied to a hash value of the input data for the signature.

11. The method according to any claim 7 , wherein all messages comprise the same single remote procedure call, RPC, identifier.

12. A target device comprising:

a processor; and

a memory storing instructions that, when executed by the processor, cause the target device to:

receive a configuration request message from a user device, the configuration request message comprising a configuration request and a request signature, wherein the configuration request message includes a unique session identifier, and wherein the request signature is based on the configuration request and a secret key of the user device;

verify the request signature to determine whether configuration request message is valid, based on the configuration request and a public key for the user device;

transmit a configuration response message to the user device only when the configuration request message is valid, the configuration response message comprising a configuration response and a response signature, wherein the response signature is a cryptographic signature of a combination including the configuration response and the request signature, the response signature derived by using the secret key of the target device in a cryptographic signing operation;

receive a configuration commit message from the user device only when the configuration request message is valid, the configuration commit message comprising a configuration commit indicator and a commit signature, wherein the commit signature is a cryptographic signature of a combination including the configuration commit indicator and the response signature, and is generated based on the secret key of the user device; and

verify the commit signature to determine whether configuration commit message is valid, based on the configuration commit indicator, the response signature and a public key for the user device;

wherein the target device is configured to store the messages, including the signatures.

13. A non-transitory computer readable medium storing a computer program for configuring a target device, the computer program comprising computer program code which, when run on a target device causes the target device to:

receive a configuration request message from a user device, the configuration request message comprising a configuration request and a request signature, wherein the configuration request message includes a unique session identifier, and wherein the request signature is based on the configuration request and a secret key of the user device;

verify the request signature to determine whether configuration request message is valid, based on the configuration request and a public key for the user device;

transmit a configuration response message to the user device only when the configuration request message is valid, the configuration response message comprising a configuration response and a response signature, wherein the response signature is a cryptographic signature of a combination including the configuration response and the request signature, the response signature derived by using the secret key of the target device in a cryptographic signing operation;

receive a configuration commit message from the user device only when the configuration request message is valid, the configuration commit message comprising a configuration commit indicator and a commit signature, wherein the commit signature is a cryptographic signature of a combination including the configuration commit indicator and the response signature, and is generated based on the secret key of the user device; and

verify the commit signature to determine whether configuration commit message is valid, based on the configuration commit indicator, the response signature and a public key for the user device;

wherein the target device is configured to store the messages, including the signatures.