[Bluez-users] Key exchange before pairing

[Jordi Jaen Pallares <jordijp@gmail.com>]

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Hi @ll !


I would like to know if it is possible to perform a "peer key exchange" 
prior to the pairing operation, in order to for example, have the peers 
exchange some extra information about them and be able for example to 
look-up different PINs for every different service / connection / device.

I have written a little program using rfcomm sockets (although I am planing 
to change them to BNEP ones) which carries out the data exchange without 
problems as long as the security manager is set to 'none'.

But I would like to be able to replace the normal pairing procedure with 
this "key exchange between bluetooth peers" procedure: 

* it is then possible to trigger (maybe via 'pin_helper' ?) a data exchange 
between the two bluetooth sockets (using raw L2CAP sockets, for example) 
while the devices are _not paired_ and while the security level is set at 
least to authentication ?

* I tried to change the rfcomm "working" sockets program to L2CAP sockets, 
but then I don´t know which Protocol Service MUX (psm) value I might have to 
set for this sockets to have them connect successfully (the one from an 
already existing service, one of the reserved values?!). 

I tried different odd values greater than 1 for the psm (using htobs(psm)) 
and I get the following error message: 

Cannot connect to socket: Connection refused (111)

I would really appreciate it if you could help me out or give me some advise 
on these topics.


Best Regards,


Jordi

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