Encrypted Advertising

Overview

This sample demonstrates the use of the encrypted advertising feature, such as:

  • the exchange of the session key and the initialization vector using the Key Material characteristic,

  • the encryption of advertising payloads,

  • the decryption of those advertising payloads,

  • and the update of the Randomizer field whenever the RPA is changed.

To use the bt_ead_encrypt() and bt_ead_decrypt() functions, you must enable the Kconfig symbol CONFIG_BT_EAD.

While this sample uses extended advertising, it is not mandatory when using the encrypted advertising. The feature can be used with legacy advertising as well.

Requirements

  • Two boards with Bluetooth Low Energy support

  • Two boards with a push button connected via a GPIO pin, see the Button sample for more details

Building and Running

This sample can be found under samples/bluetooth/encrypted_advertising in the Zephyr tree.

See bluetooth samples section for details.

This sample uses two applications, so two devices need to be setup. Flash one device with the central application, and another device with the peripheral application.

The two devices should automatically connect if they are close enough.

After the boards are connected, you will be asked to press the configured push button on both boards to confirm the pairing request.

Here are the outputs you should get by default:

Peripheral:

*** Booting Zephyr OS build zephyr-v3.3.0-1872-g6fac3c7581dc ***
<inf> ead_peripheral_sample: Advertising data size: 64
Passkey for 46:04:2E:6F:80:12 (random): 059306
Confirm passkey by pressing button at gpio@50000000 pin 11...
Passkey confirmed.
<inf> ead_peripheral_sample: Advertising data size: 64

Central:

*** Booting Zephyr OS build zephyr-v3.3.0-1872-g6fac3c7581dc ***
Passkey for 6C:7F:67:C2:8B:29 (random): 059306
Confirm passkey by pressing button at gpio@50000000 pin 11...
Passkey confirmed.
<inf> ead_central_sample: Received data size: 64
<inf> ead_central_sample: len : 10
<inf> ead_central_sample: type: 0x09
<inf> ead_central_sample: data:
                          45 41 44 20 53 61 6d 70  6c 65                   |EAD Samp le
<inf> ead_central_sample: len : 8
<inf> ead_central_sample: type: 0xff
<inf> ead_central_sample: data:
                          05 f1 5a 65 70 68 79 72                          |..Zephyr
<inf> ead_central_sample: len : 7
<inf> ead_central_sample: type: 0xff
<inf> ead_central_sample: data:
                          05 f1 49 d2 f4 55 76                             |..I..Uv
<inf> ead_central_sample: len : 4
<inf> ead_central_sample: type: 0xff
<inf> ead_central_sample: data:
                          05 f1 c1 25                                      |...%
<inf> ead_central_sample: len : 3
<inf> ead_central_sample: type: 0xff
<inf> ead_central_sample: data:
                          05 f1 17                                         |...

See also

Bluetooth APIs