Re: [Quake-devel] Authentication

[<pa...@co...>]

> > HOW IT WORKS
> > ============
> > 
> > It's basically a port of the netrek scheme, but much re-written to
> > deal with UDP packet loss.
> > 
> > At the low level, the server sends the client an authreq packet with
> > a random number in it.  The client encodes this with its public
> > key.
> 
> The client encodes it with the server's public key, right?  That would be 
> effectively authenticating the server to the client (making sure that 
> ONLY this server can host this session).

No.  The client encodes it with it's own _private_ key, and then
it's decoded at the other end with the client's _public_ key. RSA
is symmetric WRT signing/authentication.

> 
> > If the client fails to reply within 10 seconds, it is sent another
> > packet, and again until 40 seconds elapse with no authnetication.
> > A new authentication reqest is sent every 10 seconds.  Each request
> > causes the seesion key to be changed
> 
> The client better be sending it's IP and perhaps a timestamp in the 
> packet encrypted with the session key, otherwise some third party can 
> sniff the packets and just retransmit them and hijack the connection.  I 
> would suggest that the session key obtained in the first interchange be 
> used for some sort of symmetric encryption on authentication 
> packets...doing PKI encryption on auth packets would take forever.  Use 
> something like DES for the intermittent auth packets.
> > 

This last point below should deal with that.

> > Actually encrypt the seesion (will remove man-in-the-middle attack).
> > 

Patrick.