[nrf fromtree] Bluetooth: Shell: Add support for EAD

Add new commands to manage the Encrypted Advertising Data feature.

Overview of those new commands:

- `bt encrypted-ad set-keys`: set key materials (session key and
  initialisation vector) used for encrypted and decryption of EAD;
- `bt encrypted-ad add-ad`: store a given advertising data structure;
- `bt encrypted-ad add-ead`: encrypt the given advertising data
  structres and store the generated AD structure;
- `bt encrypted-ad commit-ad`: set the AD of the selected advertiser
  with the stored AD;
- `bt encrypted-ad clear-ad`: remove all stored AD;
- `bt encrypted-ad decrypt-scan`: decrypt data using the previously set
  key materials when receiving AD with type `0x31`.

The documentation of the Bluetooth Shell has been updated to include
those new commands.

Signed-off-by: Théo Battrel <[email protected]>
(cherry picked from commit 4a55bc0)

doc/connectivity/bluetooth/bluetooth-shell.rst

@@ -228,6 +228,90 @@ Let's now have a look at some extended advertising features. To enable extended
 
 This will create an extended advertiser, that is connectable and non-scannable.
 
+Encrypted Advertising Data
+==========================
+
+Zephyr has support for the Encrypted Advertising Data feature. The :code:`bt encrypted-ad`
+sub-commands allow managing the advertising data of a given advertiser.
+
+To encrypt the advertising data, key materials need to be provided, that can be done with :code:`bt
+encrypted-ad set-keys <session key> <init vector>`. The session key is 16 bytes long and the
+initialisation vector is 8 bytes long.
+
+You can add advertising data by using :code:`bt encrypted-ad add-ad` and :code:`bt encrypted-ad
+add-ead`. The former will take add one advertising data structure (as defined in the Core
+Specification), when the later will read the given data, encrypt them and then add the generated
+encrypted advertising data structure. It's possible to mix encrypted and non-encrypted data, when
+done adding advertising data, :code:`bt encrypted-ad commit-ad` can be used to apply the change to
+the data to the selected advertiser. After that the advertiser can be started as described
+previously. It's possible to clear the advertising data by using :code:`bt encrypted-ad clear-ad`.
+
+On the Central side, it's possible to decrypt the received encrypted advertising data by setting the
+correct keys material as described earlier and then enabling the decrypting of the data with
+:code:`bt encrypted-ad decrypt-scan on`.
+
+.. note::
+
+        To see the advertising data in the scan report :code:`bt scan-verbose-output` need to be
+        enabled.
+
+.. note::
+
+        It's possible to increase the length of the advertising data by increasing the value of
+        :kconfig:option:`CONFIG_BT_CTLR_ADV_DATA_LEN_MAX` and
+        :kconfig:option:`CONFIG_BT_CTLR_SCAN_DATA_LEN_MAX`.
+
+Here is a simple example demonstrating the usage of EAD:
+
+.. tabs::
+
+        .. group-tab:: Peripheral
+
+                .. code-block:: console
+
+                        uart:~$ bt init
+                        ...
+                        uart:~$ bt adv-create conn-nscan ext-adv
+                        Created adv id: 0, adv: 0x81769a0
+                        uart:~$ bt encrypted-ad set-keys 9ba22d3824efc70feb800c80294cba38 2e83f3d4d47695b6
+                        session key set to:
+                        00000000: 9b a2 2d 38 24 ef c7 0f  eb 80 0c 80 29 4c ba 38 |..-8$... ....)L.8|
+                        initialisation vector set to:
+                        00000000: 2e 83 f3 d4 d4 76 95 b6                          |.....v..         |
+                        uart:~$ bt encrypted-ad add-ad 06097368656C6C
+                        uart:~$ bt encrypted-ad add-ead 03ffdead03ffbeef
+                        uart:~$ bt encrypted-ad commit-ad
+                        Advertising data for Advertiser[0] 0x81769a0 updated.
+                        uart:~$ bt adv-start
+                        Advertiser[0] 0x81769a0 set started
+
+        .. group-tab:: Central
+
+                .. code-block:: console
+
+                        uart:~$ bt init
+                        ...
+                        uart:~$ bt scan-verbose-output on
+                        uart:~$ bt encrypted-ad set-keys 9ba22d3824efc70feb800c80294cba38 2e83f3d4d47695b6
+                        session key set to:
+                        00000000: 9b a2 2d 38 24 ef c7 0f  eb 80 0c 80 29 4c ba 38 |..-8$... ....)L.8|
+                        initialisation vector set to:
+                        00000000: 2e 83 f3 d4 d4 76 95 b6                          |.....v..         |
+                        uart:~$ bt encrypted-ad decrypt-scan on
+                        Received encrypted advertising data will now be decrypted using provided key materials.
+                        uart:~$ bt scan on
+                        Bluetooth active scan enabled
+                        [DEVICE]: 68:49:30:68:49:30 (random), AD evt type 5, RSSI -59   shell C:1 S:0 D:0 SR:0 E:1 Prim: LE 1M, Secn: LE 2M, Interval: 0x0000 (0 us), SID: 0x0
+                                [SCAN DATA START - EXT_ADV]
+                                Type 0x09:    shell
+                                Type 0x31: Encrypted Advertising Data: 0xe2, 0x17, 0xed, 0x04, 0xe7, 0x02, 0x1d, 0xc9, 0x40, 0x07, uart:~0x18, 0x90, 0x6c, 0x4b, 0xfe, 0x34, 0xad
+                                [START DECRYPTED DATA]
+                                Type 0xff: 0xde, 0xad
+                                Type 0xff: 0xbe, 0xef
+                                [END DECRYPTED DATA]
+                                [SCAN DATA END]
+                        ...
+
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