Subject: Re: [karp] Please take a look at draft-hartman-karp-ops-model-00.txt

From: Sam Hartman <[email-masked]>
Date: Thu, 21 Oct 2010 15:36:19 -0400

>>>>> "Bill" == Bill Atwood <[email-masked]> writes:

    Bill> Sam, I have read karp ops model document, and learned some
    Bill> When multicast is used from a 'speaker' to its neighbors, and
    Bill> assuming that a source address is a permitted selector for
    Bill> multicast security associations (as defined in the most recent
    Bill> IPsec specifications), then a router can distinguish packets
    Bill> from each of its peers (neighbors), and utilize a different
    Bill> Security Association for each one.  Clearly this will require
    Bill> automated key management, but it will also give the smallest
    Bill> vulnerability if a key is compromised.

Hi.  I believe that the upcoming 01 version of the ops model document
will address your other comments.

However I'm a bit confused by the above comment.  I don't understand how
you can reduce the affect of key compromise by having source-specific
SAs.
As I understand it, you need the keys for all the senders in order to
verify packets.
So, while the protocol is correctly operating, only the correct source
will send with a given key. However, I don't see anything that prevents
a sender from using someone else's key.

RFC 4359 does provide a way to sign each packet using an RSA key;
certainly with that approach then you can distinguish senders.  My
guess, though is that the routing community will decide that an RSA sign
operation for each packet send and an RSA verify for each reception is
too expensive. Given our scope,I'm not sure determining the sender of a
packet is important.

I do appreciate your review and thanks for your comments on this and
other drafts.

---

From: Sam Hartman <[email-masked]>
Date: Sun, 24 Oct 2010 17:54:19 -0400

Hi. I sent some more detailed responses to your comments previously, but
I wanted to confirm that we'll be uploading a version of
draft-hartman-karp-ops-model-01 tomorrow that we believe addresses your
comments.