Hi,
I have a problem connecting to a BT device from a Linux desktop –
pairing fails, while an Android phone pairs properly.
The obvious difference in the btsnoop logs is in the pairing request.
Android:
< ACL Data TX: Handle 65 flags 0x00 dlen 11
#995 150.491086
SMP: Pairing Request (0x01) len 6
IO capability: KeyboardDisplay (0x04)
OOB data: Authentication data not present (0x00)
Authentication requirement: Bonding, MITM, Legacy, No Keypresses
(0x05)
Max encryption key size: 16
Initiator key distribution: EncKey IdKey Sign (0x07)
Responder key distribution: EncKey IdKey Sign (0x07)
[...]
> ACL Data RX: Handle 65 flags 0x02 dlen 11
#1006 150.571137
SMP: Pairing Response (0x02) len 6
IO capability: NoInputNoOutput (0x03)
OOB data: Authentication data not present (0x00)
Authentication requirement: Bonding, No MITM, Legacy, No
Keypresses (0x01)
Max encryption key size: 16
Initiator key distribution: EncKey (0x01)
Responder key distribution: EncKey (0x01)
And on Linux:
< ACL Data TX: Handle 16 flags 0x00 dlen 11 #53 [hci0]
132.273100
SMP: Pairing Request (0x01) len 6
IO capability: NoInputNoOutput (0x03)
OOB data: Authentication data not present (0x00)
Authentication requirement: Bonding, No MITM, SC, No Keypresses,
CT2 (0x29)
Max encryption key size: 16
Initiator key distribution: EncKey Sign LinkKey (0x0d)
Responder key distribution: EncKey IdKey Sign LinkKey (0x0f)
[...]
> ACL Data RX: Handle 16 flags 0x02 dlen 6 #57 [hci0]
132.362160
SMP: Pairing Failed (0x05) len 1
Reason: Invalid parameters (0x0a)
So it looks like 'Bonding, MITM, Legacy, No Keypresses' used by Android
works and 'Bonding, No MITM, SC, No Keypresses, CT2' used by the desktop
Linux (bluez 5.62, kernel '5.6.2-050602-lowlatency' from Ubuntu) does
not (note: I am still quite ignorant about Bluetooth stuff).
So my question is: is there any way to force using legacy pairing? Even
if that requires bluez or kernel patching (though, I would rather avoid
that).
Greets,
Jacek
