[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: SOI: identity protection and DOS
Radia Perlman - Boston Center for Networking writes:
> Derek said:
> >>I happen to agree with Radia's point that you should try to protect
> >>the initiator's identity before the responder's identity (which
> >>implies the responder should authenticate to the initiator first).
>
> Actually, Dan and Charlie changed my mind about that. The problem with
> the responder revealing identity information first is that ANYONE can
> initiate an IPsec connection to an IP address and find out who is there
> without ever divulging their identity.
Ah. In other words, it should imitate real life
conversations where the responder gets to say
"who's there?" rather than the initiator.
> If it's the initiator that reveals identity first then the only threat is
> from an active attacker impersonating the responder's IP address and lying
> in wait. (the initiator's ID is hidden from an eavesdropper and revealed
> only to whatever is sitting at the IP address the initiator connected to).
> If it's the responder that reveals identity first, then (assuming
> it's not a strict client/server model where the nodes that need identity
> protection never respond to IPsec connect initiates and only initiate
> them) it is trivial to find out who is at an IP address.
Which means that you're forced into a full round
trip first to protect the initiator's identity. This
is precisely why I think that identity
protection should be an optional tradeoff of
SA establishment speed vs. privacy, especially
since the privacy protection in a large number
of cases is subject to simple traffic analysis
guessing.
Mike
Follow-Ups:
References: