what is different between pairing vs bonding , STK vs LTK

[Giang]

hi all , I am looking out theory about SM layer in BLE . I read CoreV5.0 but I do not understand much about pairing , bonding , STK , LTK . Can you give me some document about that ? Thank !!!

[Giang]

Hi , I am working with platform NRF52832 of Nodric . I run my board with example of BLE such as : NUS service, LBS sevice ... and board connect with each other and send data . So , I think my board don't pairing and bonding , it only connect normal in GAP layer . So , I have questions , Is the connection between my boards encrypted ?? And how PDUs package in Link Layer encrypted by ?

[Petter Myhre]

Those examples doesn't support pairing. Take a look at for example ble_app_hrs. I would also recommend to study the MSCs, for example this one.

[Giang]

Hi , in connection nomal (don't pairing and don't bonding) , The Link Layer provides encryption and authentication using Counter with Cipher Block Chaining-Message Authentication Code (CCM) Mode . CCM requires a new temporal key whenever encryption is started . So where is new temporal key create ? Is it session key ? And where is session key create (if don't pairing and bonding , won't have STK and LTK )

[Petter Myhre]

You need to have paired or bonded to encrypt the link, if you haven't the link will not be encrypted.