what is different between pairing vs bonding , STK vs LTK

RE: what is different between pairing vs bonding , STK vs LTK

Petter Myhre — Tue, 05 Dec 2017 11:50:14 GMT

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

RE: what is different between pairing vs bonding , STK vs LTK

Giang — Sat, 02 Dec 2017 05:17:02 GMT

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 )

RE: what is different between pairing vs bonding , STK vs LTK

Petter Myhre — Thu, 30 Nov 2017 12:31:25 GMT

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.

RE: what is different between pairing vs bonding , STK vs LTK

Giang — Thu, 30 Nov 2017 11:55:26 GMT

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 ?

RE: what is different between pairing vs bonding , STK vs LTK

Petter Myhre — Thu, 30 Nov 2017 11:14:10 GMT

The link can either be encrypted by pairing, or if you have previously bonded, you can encrypt the link with LTK.
I'm don't know how to answer this, they are two different layers in the stack. Could you be more specific?
Then you need to pair or bond...

RE: what is different between pairing vs bonding , STK vs LTK

Giang — Thu, 30 Nov 2017 10:51:49 GMT

Thank for reply , I have question .

If don't pairing or bonding , Is the Link Layer connection encrypt ? Then, Is the PDU package in Link Layer encrypted for send from device A to device B ?
What is diffence between Link Layer connection and GAP connection ? or they are one
If don't pairing and bonding , LL hasn't STK or LTK , so how LL encrypt by ?

RE: what is different between pairing vs bonding , STK vs LTK

Petter Myhre — Thu, 30 Nov 2017 10:20:53 GMT

If you have bonded LTK will be used for subsequent connections. Not the connection when you pair.
Correct.

RE: what is different between pairing vs bonding , STK vs LTK

Giang — Thu, 30 Nov 2017 09:43:00 GMT

Hi , as I know . In phase 2 of pairing/bonding , has 2 option

LE legacy pairing , STK will be created for encrypt connection , then if pairing , STK is sent to LL for create session key . If bonding , LTK is created replace STK , then LTK is sent to LL for create session key
if LE secure connection pairing , LTK will be created for encrypt connection and sent to LL

Is it correct ? thank !!!

RE: what is different between pairing vs bonding , STK vs LTK

Petter Myhre — Tue, 28 Nov 2017 16:07:02 GMT

There is no LTK in pairing. Only in bonding.
In bonding there is only one LTK. This is used in all subsequent connections.

RE: what is different between pairing vs bonding , STK vs LTK

Giang — Tue, 28 Nov 2017 15:44:45 GMT

Hi , sorry because my English isn't good . I want to ask :

In pairing , each connect , LTK is created and diffenrence value LTK privious ?
In bonding , LTK1 is stored for the next connection (2nd) . So in the connection 2 , is new LTK2 created ? Or in the next connection (3nd) still LTK1 for encrypt

RE: what is different between pairing vs bonding , STK vs LTK

Petter Myhre — Tue, 28 Nov 2017 14:35:03 GMT

1)What do you mean by each re-connect is secure? If you don't bond you have to pair every time, if this is secure or not depends on how you pair, if you are doing Just Works, Passkey Entry, OOB, LESC and so on. There is no LTK generation when you don't bond.

2)What do you mean by when the new LTK is created? The LTK is created once, then this is used to encrypt the link in future connections.

3)You have to be more specific on what it is you don't understand.

RE: what is different between pairing vs bonding , STK vs LTK

Giang — Sun, 26 Nov 2017 01:37:50 GMT

Hi Emil Lenngren , I want to ask some question .

In pairing , keys don't distribute , so each re-connect secure , we will re-pairing , so the new STK and LTK is created , so have we changed ?
In bonding , LTK is stored . So each reconnect , old - LTK will be used . So , when the new LTK is created ?
Can you discribe for me the process phase 3 performance between master and slave and how the LTK is used in Link layer ?

Thank !!!

RE: what is different between pairing vs bonding , STK vs LTK

Giang — Sat, 25 Nov 2017 03:04:08 GMT

Thank for reply , I also want to ask about STK and LTK . As I understand , STK is used to encrypt the connection , which will be used for distribute LTK , EDIV , Rand , IRK , CSRK , public Address between Host of Master and Host of Slave . Then , host send LTK to Link layer for create session key , session key is used to encrypt all PDUs in Link Layer . I understand that is correct ? Pls help me , thank !!!

RE: what is different between pairing vs bonding , STK vs LTK

shibshab — Fri, 24 Nov 2017 20:23:53 GMT

Pairing: Select a key, use this key to encrypt data between these devices. When the devices are disconnected, everything is forgotten and it is if the devices never knew each other. The next time you want to talk secretly to the same device, everything has to be done all over again.

Bonding: First, do Pairing to have a secure link, then exchange keys for the next time we meet, so that we don't need to perform Pairing again to have a secure link.

By doing bonding, the user will (for example) not have to enter the 6 digit passkey every time the smartwatch is connected to the phone.