Ultra wideband secure ranging

Patent metadata

Field	Value
Publication number	US-11184153-B2
Application number	US-201916459733-A
Country	US
Kind code	B2
Filing date	Jul 2, 2019
Priority date	Jul 5, 2018
Publication date	Nov 23, 2021
Grant date	Nov 23, 2021

Abstract

Methods and apparatuses are presented to generate, and verify reception of, ultra wideband (UWB) communications, e.g., to perform secure UWB ranging. Verifier and prover messages may be encoded on top of random cryptographically secure training sequence (STS) of pulses, organized in blocks such that a given block corresponds to a given message bit. In some scenarios, a first STS may be encoded using a verifier message not known to a recipient device. A second STS may be received from the recipient device, encoded with an unknown prover message. A third STS may also be received, encoded with an authentication message generated using the verifier message and the authentication message. Verification of the authentication message can therefore confirm that the recipient device received the first STS, and that the recipient device is the authentic source of the second STS. Thus, the second STS may be relied upon, e.g., for ranging calculations.

First claim

What is claimed is:

1. A method of generating a first ultra wideband (UWB) packet, the method comprising:
by a wireless communication device:
generating a first secure training sequence (STS) that comprises a cryptographically encoded random STS pulse sequence; and
dividing the STS pulse sequence between two or more subblocks, wherein a subblock of the two or more subblocks is associated with a bit corresponding to a separate verifier message, wherein a polarity of a plurality of pulses in the subblock is set based on the bit.

2. The method of claim 1 , further comprising:
by the wireless communication device:
inserting a gap between two subblocks of the two or more subblocks.

3. The method of claim 1 , further comprising:
by the wireless communication device:
transmitting the first UWB packet to a remote communication device, wherein the first STS is known to the remote communication device, and wherein the verifier message is not known to the remote communication device.

4. The method of claim 3 , further comprising:
by the wireless communication device:
receiving from the remote communication device a second UWB packet comprising a second STS that is divided between two or more subblocks, wherein a subblock of the two or more subblocks of the second STS is associated with a bit corresponding to a separate prover message, wherein a polarity of a plurality of pulses in the subblock of the second STS is based on the bit.

5. The method of claim 4 , wherein the second STS is known to the wireless communication device, and wherein the prover message is not known to the wireless communication device.

6. The method of claim 5 , further comprising:
by the wireless communication device:
receiving from the remote communication device a third UWB packet comprising a third STS that is divided between two or more subblocks, wherein a subblock of the two or more subblocks of the third STS is associated with a bit corresponding to a separate authentication message, wherein a polarity of a plurality of pulses in the subblock of the third STS is based on the bit, wherein the third STS is known to the wireless communication device, and wherein the authentication message is the result of applying an algorithm to the verifier message and the prover message;
determining a first estimate of the authentication message by comparing the known values of the pulses of the third STS with the received values of the pulses of the third UWB packet; and
determining that the remote wireless device received the first UWB packet based on the first estimate of the authentication message.

7. The method of claim 6 , wherein determining that the remote wireless device received the first UWB packet based on the first estimate of the authentication message comprises:
determining an estimate of the prover message by comparing the known values of the pulses of the second STS with the received values of the pulses of the second UWB packet;
determining a second estimate of the authentication message by applying the algorithm to the verifier message and the estimate of the prover message; and
determining that the first estimate of the authentication message and the second estimate of the authentication message are sufficiently similar.

8. The method of claim 6 , wherein determining that the remote wireless device received the first UWB packet based on the first estimate of the authentication message comprises:
determining a first estimate of the prover message by comparing the known values of the pulses of the second STS with the received values of the pulses of the second UWB packet;
determining a second estimate of the prover message by applying a reverse of the algorithm to the first estimate of the authentication message, using the verifier message; and
determining that the first estimate of the prover message and the second estimate of the prover message are sufficiently similar.

9. A wireless communication device, comprising:
a pseudorandom number generator configured to generate a first secure training sequence (STS) that is known to a prover device;
an encoder configured to encode the first STS using a verifier message that is not known to the prover device;
transmit circuitry configured to transmit a message comprising the encoded first STS to the prover device;
receive circuitry configured to:
receive from the prover device a second message comprising a second STS that is known to the wireless communication device and that is encoded using a prover message that is not known to the wireless communication device; and
receive from the prover device a third message comprising a third STS that is known to the wireless communication device and that is encoded using a message authentication code, wherein the message authentication code is the result of applying an algorithm to the verifier message and the prover message;

a decoder configured to:
determine an estimate of the prover message by decoding the second STS;
determine a first estimate of the message authentication code by decoding the third STS; and
determine a second estimate of the message authentication code by applying the algorithm to the verifier message and the estimate of the prover message; and

a comparator configured to determine whether the first estimate of the authentication code and the second estimate of the message authentication code are similar to a specified degree.

10. The wireless communication device of claim 9 , further comprising:
a ranging module configured to determine a range between the wireless communication device and the prover device based on a reception time of the message comprising the second STS, in response to determining that the first estimate of the message authentication code and the second estimate of the message authentication code are similar to the specified degree.

11. The wireless communication device of claim 9 , further comprising:
a modulator configured to modulate the first message as an ultra wideband (UWB) communication.

12. The wireless communication device of claim 9 , wherein encoding the first STS comprises encoding a plurality of subblocks of the first STS with respective bits of the verifier message, each subblock comprising a plurality of pulses.

13. The wireless communication device of claim 12 , wherein encoding a subblock of the first STS comprises reversing the polarity of the plurality of pulses of the subblock in response to the respective bit of the verifier message having a first value, and maintaining the original polarity of the plurality of pulses of the subblock in response to the respective bit of the verifier message having a second value.

14. The wireless communication device of claim 12 , wherein encoding the first STS further comprises separating the subblocks with guard intervals.

15. A method for securely exchanging wireless communication messages
by a verifier device:
encoding a first secure training sequence (STS) that is known to a prover device, using a verifier message that is not known to the prover device;
transmitting to the prover device a first message comprising the first STS;
receiving from the prover device a second message comprising a second STS that is known to the verifier device and that is encoded using a prover message that is not known to the verifier device;
determining an estimate of the prover message by decoding the second STS;
receiving from the prover device a third message comprising a third STS that is known to the verifier device and that is encoded using a message authentication code, wherein the message authentication code is the re

Assignees

• Apple Inc

Inventors

• Hammerschmidt Joachim S
• Sasoglu Eren

Classifications

• H04W12/106

  Packet or message integrity · CPC title

• H04W12/06

  Authentication · CPC title

• H04L9/065 Primary

  Encryption by serially and continuously modifying data stream elements, e.g. stream cipher systems, RC4, SEAL or A5/3 · CPC title

• H04L9/3242 Primary

  involving keyed hash functions, e.g. message authentication codes [MACs], CBC-MAC or HMAC · CPC title

• H04L2209/805

  Lightweight hardware, e.g. radio-frequency identification [RFID] or sensor · CPC title