Out-of-band key for ranging

1 . An apparatus for wireless communication at a first device, comprising:

one or more memories; and

one or more processors, coupled to the one or more memories, individually or collectively configured to cause the first device to:

obtain an out-of-band (OOB) key that is shared OOB with respect to a ranging session defined in-band between the first device and a second device;

generate, during the ranging session using the OOB key itself or in combination with information used in-band, one or more first inputs to a first scrambling sequence used in the ranging session, wherein to generate the one or more first inputs, the one or more processors are configured to cause the first device to generate an OOB initialization vector (IV); and

transmit a first message to the second device during the ranging session using the first scrambling sequence.

2 . The apparatus of claim 1 , wherein to obtain the OOB key, the one or more processors are individually or collectively configured to cause the first device to receive the OOB key from a network entity or a peer device.

3 . The apparatus of claim 1 , wherein the one or more processors are individually or collectively configured to cause the first device to transmit the OOB key to a second device OOB.

4 . The apparatus of claim 1 , wherein to obtain the OOB key, the one or more processors are individually or collectively configured to cause the first device to receive the OOB key from a network entity OOB using a communication technology that is different than a communication technology that is used in-band during the ranging session.

5 . The apparatus of claim 1 , wherein to obtain the OOB key, the one or more processors are individually or collectively configured to cause the first device to receive the OOB key from a network entity on a secure provisioning channel.

6 . The apparatus of claim 5 , wherein the secure provisioning channel is terminated by a root of trust of the first device that is associated with key management or terminated by a secure element of the first device having a high security assurance level.

7 . The apparatus of claim 1 , wherein the one or more processors are individually or collectively configured to cause the first device to securely store the OOB key at the first device prior to starting the ranging session.

8 . The apparatus of claim 7 , wherein to securely store the OOB key, the one or more processors are individually or collectively configured to cause the first device to store the OOB key at a root of trust of the first device or in a secure element of the first device.

9 . The apparatus of claim 1 , wherein the ranging session is associated with a short-range wireless protocol, and wherein the first device is a central device and the second device is a peripheral device.

10 . The apparatus of claim 1 , wherein the ranging session is associated with a short-range wireless protocol, and wherein the first device is a user equipment (UE) and the second device is associated with a locking mechanism.

11 . The apparatus of claim 1 , wherein the information used in-band includes a set of derivation diversifiers, and wherein to generate the one or more first inputs, the one or more processors are individually or collectively configured to cause the first device to generate the one or more first inputs using the OOB key and the set of derivation diversifiers.

12 . The apparatus of claim 11 , wherein the set of derivation diversifiers is associated with a long term key and includes an initialization vector, an initialization nonce, and a personalization vector.

13 . The apparatus of claim 11 , wherein the one or more processors, to cause the first device to generate the one or more first inputs to the first scrambling sequence, are configured to cause the first device to generate, for a first ranging iteration of the ranging session with the second device, a first key and a first nonce using the OOB IV and the set of derivation diversifiers.

14 . The apparatus of claim 13 , wherein the one or more processors are individually or collectively configured to cause the first device to:

generate, for a second ranging iteration, a second key and a second nonce as second inputs to a second scrambling sequence; and

transmit, to the second device as part of the second ranging iteration, a second message using the second scrambling sequence.

15 . An apparatus for wireless communication at a second device, comprising:

one or more memories; and

one or more processors, coupled to the one or more memories, individually or collectively configured to cause the second device to:

receive, from a first device or a network entity, an out-of-band (OOB) key that is shared OOB with respect to a ranging session defined in-band between a first device and the second device;

generate, in-band using the OOB key itself or in combination with information used in-band, one or more inputs to a first scrambling sequence used in the ranging session, wherein to generate the one or more inputs, the one or more processors are configured to cause the second device to generate an OOB initialization vector (IV); and

receive a first message from the first device that uses the first scrambling sequence.

16 . The apparatus of claim 15 , wherein the one or more processors are individually or collectively configured to cause the second device to decode the first message using the first scrambling sequence.

17 . The apparatus of claim 15 , wherein the one or more processors are individually or collectively configured to cause the second device to securely store the OOB key at the second device prior to starting the ranging session.

18 . An apparatus for wireless communication at a network entity, comprising:

one or more memories; and

one or more processors, coupled to the one or more memories, individually or collectively configured to cause the network entity to:

receive, from a first device, a request for an out-of-band (OOB) key associated with a ranging session at the first device; and

transmit the OOB key to the first device OOB upon a successful attestation of the first device with the network entity, wherein the OOB key, in combination with information used in-band, is used to generate OOB initialization vector (IV) for one or more first inputs to a first scrambling sequence used in the ranging session.

19 . The apparatus of claim 18 , wherein to transmit the OOB key, the one or more processors are configured to cause the network entity to transmit the OOB key on a secure provisioning channel.

20 . The apparatus of claim 18 , wherein the information used in-band includes a set of derivation diversifiers, wherein the set of derivation diversifiers is associated with a long term key and includes an initialization vector, an initialization nonce, and a personalization vector.