SYSTEMS AND METHODS FOR DISTANCE BOUNDING TO AN AUTHENTICATED DEVICE

1 . A method by a verifier device, comprising:

authenticating a target device;

establishing a shared key with the target device;

sending a bounding sequence encrypted with the shared key to the target device; and

performing a distance upper bound determination procedure with the target device based on the bounding sequence.

2 . The method of claim 1 , wherein the encrypted bounding sequence is sent to the target device over a secure channel upon authenticating the target device and establishing the shared key.

3 . The method of claim 1 , wherein the bounding sequence is a random value or a sequence of random values.

4 . The method of claim 1 , wherein a processing time multiplier for a target device response is determined by the bounding sequence or a transformation of the bounding sequence.

5 . The method of claim 4 , wherein the processing time multiplier indicates an amount of time that the target device delays responding to a challenge sent by the verifier device.

6 . The method of claim 1 , wherein the distance upper bound is an upper bound on the distance between the verifier device and the target device.

7 . The method of claim 1 , wherein performing the distance upper bound determination procedure comprises:

measuring a round-trip time to send a challenge to the target device and receive a response that is delayed by a processing time multiplier determined by the bounding sequence; and

calculating the distance upper bound using the measured round-trip time and the processing time multiplier.

8 . The method of claim 1 , wherein performing the distance upper bound determination procedure comprises:

measuring a first round-trip time to receive a first response from the target device corresponding to a first challenge sent to the target device;

measuring a second round-trip time to receive a second response from the target device corresponding to a second challenge sent to the target device, wherein the target device scales a processing time for the second response by a processing time multiplier indicated by the bounding sequence or a transformation of the bounding sequence;

determining a transit time measurement based on the first round-trip time, the second round-trip time and the processing time multiplier; and

determining the distance upper bound by multiplying the transit time measurement by the speed of light.

9 . The method of claim 1 , wherein a physical layer of the verifier device sends the encrypted bounding sequence and a bounding layer of the verifier device performs the distance upper bound determination procedure.

10 . A verifier device, comprising:

a processor;

a memory in communication with the processor; and

instructions stored in the memory, the instructions executable by the processor to:

authenticate a target device;

establish a shared key with the target device;

send a bounding sequence encrypted with the shared key to the target device; and

perform a distance upper bound determination procedure with the target device based on the bounding sequence.

11 . The verifier device of claim 10 , wherein the encrypted bounding sequence is sent to the target device over a secure channel upon authenticating the target device and establishing the shared key.

12 . The verifier device of claim 10 , wherein the bounding sequence is a random value or a sequence of random values.

13 . The verifier device of claim 10 , wherein a processing time multiplier for a target device response is determined by the bounding sequence or a transformation of the bounding sequence.

14 . The verifier device of claim 13 , wherein the processing time multiplier indicates an amount of time that the target device delays responding to a challenge sent by the verifier device.

15 . The verifier device of claim 10 , wherein the distance upper bound is an upper bound on the distance between the verifier device and the target device.

16 . The verifier device of claim 10 , wherein the instructions executable to perform the distance upper bound determination procedure comprise instructions executable to:

measure a round-trip time to send a challenge to the target device and receive a response that is delayed by a processing time multiplier determined by the bounding sequence; and

calculate the distance upper bound using the measured round-trip time and the processing time multiplier.

17 . The verifier device of claim 10 , wherein the instructions executable to perform the distance upper bound determination procedure comprise instructions executable to:

measure a first round-trip time to receive a first response from the target device corresponding to a first challenge sent to the target device;

measure a second round-trip time to receive a second response from the target device corresponding to a second challenge sent to the target device, wherein the target device scales a processing time for the second response by a processing time multiplier indicated by the bounding sequence or a transformation of the bounding sequence;

determine a transit time measurement based on the first round-trip time, the second round-trip time and the processing time multiplier; and

determine the distance upper bound by multiplying the transit time measurement by the speed of light.

18 . A method by a target device, comprising:

authenticating a verifier device;

establishing a shared key with the verifier device;

receiving a bounding sequence encrypted with the shared key from the verifier device; and

performing a distance upper bound determination procedure with the verifier device based on the bounding sequence.

19 . The method of claim 18 , wherein the encrypted bounding sequence is received from the verifier target device over a secure channel upon authenticating the verifier device and establishing the shared key.

20 . The method of claim 18 , further comprising decrypting the bounding sequence using the shared key.

21 . The method of claim 18 , further comprising determining a processing time multiplier for the target device response based on the bounding sequence or a transformation of the bounding sequence.

22 . The method of claim 21 , wherein the processing time multiplier indicates an amount of time that the target device delays responding to a challenge received from the verifier device.

23 . The method of claim 18 , wherein performing the distance upper bound determination procedure comprises:

receiving, from the verifier device, a challenge that is associated with a processing time multiplier determined by the bounding sequence or a transformation of the bounding sequence; and

sending, to the verifier device, a response that is delayed by the processing time multiplier.

24 . The method of claim 18 , wherein a physical layer of the target device receives the encrypted bounding sequence and a bounding layer of the target device performs the distance upper bound determination procedure.

25 . A target device, comprising:

a processor;

a memory in communication with the processor; and

instructions stored in the memory, the instructions executable by the processor to:

authenticate a verifier device;

establish a shared key with the verifier device;

receive a bounding sequence encrypted with the shared key from the verifier device; and

perform a distance upper bound determination procedure with the verifier device based on the bounding sequence.

26 . The target device of claim 25 , wherein the encrypted bounding sequence is received from the verifier target device over a secure channel upon authenticating the verifier device and establishing the shared key.

27 . The target device of claim 25 , further comprising instructions executable to decrypt the bounding sequence using the shared key.

28 . The target device of claim 25 , further comprising instructions executable to determine a processing time multiplier for the target device response based on the bounding sequence or a transformation of the bounding sequence.

29 . The target device of claim 28 , wherein the processing time multiplier indicates an amount of time that the target device delays responding to a challenge received from the verifier device.

30 . The target device of claim 25 , wherein the instructions executable to perform the distance upper bound determination procedure comprise instructions executable to:

receive, from the verifier device, a challenge that is associated with a processing time multiplier determined by the bounding sequence or a transformation of the bounding sequence; and

send, to the verifier device, a response that is delayed by the processing time multiplier.