Subject: [Hipsec] NONCE parameter in base exchange?

From: [email-masked] (Ahrenholz, Jeffrey M)
Date: Thu Oct 7 10:35:01 2004

<snip>
> You can create separate SAs based on different NONCES, and then the=20
> hack is when an outbound packet enters ESP, the SA selection is made=20
> locally, based on Traffic Selectors including TCP/UDP ports for=20
> example, and not enforced by the ESP receivers, which hence doesn't=20
> need to be aware of the local TSs used by the ESP sender.
>=20
> This allows for separation of multiple connexions by the sender,=20
> without having to negociate TSs with TCP/UDP ports numbers in HIP=20
> itself.

Using this method, with the receiver not aware of the sender's local
TSs, you would probably have asymmetric return traffic (i.e., returning
on another SPI)(unless the receiver sets up its own TSs that happen to
exactly match the sender). But I would agree that this might be more
elegant than using multiple HIs.

<snip>
> I would vote for adding NONCE, as it make HIP SIGMA-compliant, and=20
> keep ECHO_REQ/REP.=20

Do we need both NONCE and ECHO?

> IMHO this is a minor addition which buys us provable security by=20
> conforming to the SIGMA core protocol, so I believe we don't need to=20
> wait until v2 to handle NONCEs.

I think this is a good argument too. I wouldn't mind adding the nonce.
Maybe note its future usefulness. If it replaces the ECHO_*, then it is
not very different from the ECHO_* parameter anyway.

-Jeff