Subject: [Roll] Still not described: MAC over dst when RH4 present (dst mutable but predictable)

From: Alexandru Petrescu <[email-masked]>
Date: Wed, 08 Dec 2010 12:49:05 +0100

Dear RoLL,

It seems to me that the authenticating MAC calculation over the mutable
but predictable fields (dst in base header, when RH4 present) is still
not described.  I searched the following documents:

rfc4302
draft-ietf-6man-rpl-routing-header-01
draft-ietf-roll-rpl-15

I suggest text in RPL draft-15 as follows, in this zone:

OLD
> Message authentication codes (MAC) and signatures are calculated
> over the entire unsecured IPv6 packet.  When computing MACs and
> signatures, mutable IPv6 fields are considered to be filled with
> zeroes, following the rules in Section 3.3.3.1 of [RFC4302] (IPSec
> Authenticated Header).  MAC and signature calculations are performed
> before any compression that lower layers may apply.

NEW:
    Message authentication codes (MAC) and signatures are calculated over
    the entire unsecured IPv6 packet.  When computing MACs and
    signatures, mutable IPv6 fields are considered to be filled with
    zeroes, following the rules in Section 3.3.3.1 of [RFC4302] (IPSec
    Authenticated Header).  The mutable but predictable fields (e.g. the
dst address field in the base header when RH5 is present) is treated
similraly when RH0 is used, as section A.2 of rfc4302 describes.
    MAC and signature calculations are performed
    before any compression that lower layers may apply.

It may be that you'd like this description in the RH4 draft instead of
the RPL draft.

It may be that you'd want described it in more detail, as one poster
posted in this WG detaliing an algorithm detailing how RH5 would be
protected by MAC calculation.  I support this as well.

("entire" unsecure packet is wrong too, it should say "most of it", not
"entire").

Alex