[Dundi] [RFC] GPA accountability/recourse and potential protocol addition

[Kevin P. Fleming]

Mark Spencer wrote:

> The best thing would be if there was a way to use the EID and public key 
> to somehow authenticate the call.

Yes, I originally considered proposing that, because it is proactive 
rather than reactive. However, the SIP protocol does not support it, and 
IAX doesn't either, although it could be extended to do so.

It has a bigger problem, though: I don't have the EIDs and public keys 
of every peer on the network, and it cannot be sent by the peer during 
the call setup (at least the public key can't), or it would be 
untrusted. That means you have to have some other means of obtaining the 
public key for a given EID, which requires either the other peers to 
provide that to you on request, or there would have to be some sort of 
"key servers" that would provide them. DUNDi is trying avoid that sort 
of centralization :-)

Also, I don't want to have to issue a request into the network to obtain 
the public key for a given EID whenever I get a call from them; that 
will drastically increase call setup time.

I think a reactive solution is the best we can do, and the other peers 
of the calling peer are in the best position to provide information 
about who they are. If I get time I'll put together a patch to pbx_dundi 
to provide this behavior, but it won't be for a week or more.