[p2p-hackers] P2P Authentication

[Kerry Bonin]

FWIW, this is exactly how I do it - my architecture is hybrid, the only 
non p2p resources are some secure database servers for a special class 
of data and a CA.  Every "registered" user gets any X.509 cert and has 
to store their own private keys.  Just make sure your root cert keys are 
_really_ safe - if you want new users to be able to automatically obtain 
certs, that implies network access to the CA.  Make sure you firewall 
well, scrub the incoming CSRs, and have some DDOS resistant proxies in 
front of it (client puzzles work great for that aspect.)  Using an HSM 
instead of a normal server helps, but they're expensive...

Another nice thing about certs is that you don't have to use SSL - if 
you still want a UDP based protocol, just use the cert to sign your key 
exchange, then use a stream cipher that can live w/ dropped packets.  
I've got a simple protocol for this I need to turn into an RFC and 
publish as open source, just too many other items in front of it at the 
moment...

Davide Carboni wrote:

>On 10/25/05, Frank Moore <francis.moore at rawflow.com> wrote:
>  
>
>>Hi,
>>
>>I have the following problem:
>>
>>I'm working on a hybrid p2p network where there is a central server and
>>lots of clients (peers). I need a way for clients to authenticate
>>themselves when they join the network. I've looked at doing a challenge
>>response type thing using Challenge Handshake Authentication Protocol
>>(CHAP) but that means putting a shared secret key in each client and
>>the server.
>>
>>It seems entirely possible that someone could reverse engineer the
>>client executable to get hold of the shared secret key and then write a
>>'rogue' client (or server) to subvert the network?
>>
>>Is there a standard (or any) way of authenticating peers in p2p
>>networks that doesn't require secret shared keys?
>>
>>    
>>
>
>I have a similar problem. Currently I'm thinking to use socket over
>SSL to establish a connection between peers. So my idea is:
>(1) a unique certification authority CA for the community issues
>certificates to participants who are entitled to join
>(2) once p1 connects to p2, ssl authentication via certificate is
>requested both for the 'client' and for the 'server'. If both
>certificates are issued by CA the connection is up otherwise the
>connection fails.
>
>This way, there is no need to connect to a central DB and there are
>not shared secrets but each node must keep secret its private key.
>I'm just concerned about performances.
>D.
>
>
>--
>I lose control 'cause I'm a creature of the night (Bruce and Bongo)
>--
>http://people.crs4.it/dcarboni
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>
>  
>

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