Subject: [Isms] selection criteria for ISMS proposals

From: Juergen Quittek <[email-masked]>
Date: Thu, 14 Oct 2004 17:41:01 +0200

Dear all,

We should start discussing selection criteria for proposed ISMS solutions.

Wes, at the end of the last BoF meeting you showed a slide that compared
some solutions.  Could put the list of criteria on this slide in an email
that we can use as starting point for our discussion?

Thanks,

    Juergen
-- 
Juergen Quittek        [email-masked]       Tel: +49 6221 90511-15
NEC Europe Ltd.,       Network Laboratories        Fax: +49 6221 90511-55
Kurfuersten-Anlage 36, 69115 Heidelberg, Germany   http://www.netlab.nec.de

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---

From: Wes Hardaker <[email-masked]>
Date: Thu, 14 Oct 2004 13:09:25 -0700

>>>>> On Thu, 14 Oct 2004 17:41:01 +0200, Juergen Quittek <[email-masked]> said:

Juergen> Wes, at the end of the last BoF meeting you showed a slide
Juergen> that compared some solutions.  Could put the list of criteria
Juergen> on this slide in an email that we can use as starting point
Juergen> for our discussion?

Actually, that list was a list of security features found in each
protocol and was not a reference to requirements that the WG should
consider (though obviously some would be and some wouldn't).  That
point was frequently misunderstood at the meeting, because people saw
that some administrative ones (must not modify SNMPv3) weren't in it
and some of the points that are in it they didn't care about and
didn't want it to be a requirement...  sigh...  I was just trying to
show a slide to talk about ;-)  Anyway, I also sent it out a long time
ago to the list.  Here it is again, however.  MIASMA isn't listed in
it as it was new the last time I created it.  We could update it if it
will be in consideration (currently no one has stood up for it
yet... We only have EUSM and SBSM responses so far?).

Someone should word the charter requirements/comments into single-line
sentences as well.

                                    USM    EUSM     SBSM    TLS     KRB5
                                    ---------------------------------------
Can use account infrastructure      No     AAA      Yes     Yes     1/2 (2)

Flexible identification methods     No     AAA      Yes     Yes     1/2 (2)

session-keys;                       No     Yes      Yes     Yes     central(1)
ident != integrity
(pair-wise dynamic keys)  

Negotiated auth/priv algorithms     No     No       Yes     Yes     central(1)

Negotiated SNMP Params  (3)         Yes    Yes      Yes     No  (5) Yes (4)

True replay protection              No     No       Yes     Yes     Yes

True reordering protection          No     No       1/2 (9) Yes     No

TCP                                 Yes    Yes      Yes     Yes     Yes
UDP                                 Yes    Yes      Yes     Yes (6) Yes
Others (ATM, ...)                   Yes    Yes      Yes     No      No

Identity protection                 No     No       Yes     No      No

Compression                         No     No       Yes     Yes     No

PFS                                 No     No       Yes     Yes     No (8)

Anonymous but protected             No     ?        Yes     Yes     No
(== anon authentication; multiple
 integrity sessions)

Different authorization types =     No     No       Yes     ?       No
  Different Access Rights

In use by other protocols           No     No       No      Yes     Yes

Defined                             Yes    Yes      Yes     No      Yes
Implemented                         Yes    Partial  Partial No      Yes
Deployed                            Yes    No       No      No      Yes
                                    ---------------------------------------
                                    USM    EUSM     SBSM    TLS     KRB5

Notes:

(1) central = the KDC picks what to use based on config, what the
    server/service supports and what the user/client supports.  IE,
    the kdc controls the client/server negotiations.

(2) It is probably possible to generate krb5 tickets from alternative
    mechanisms rather than negotiating typically kerberos through the
    KDC, though the work has not been standardized to date.

(3) The important SNMP parameter that needs negotiation is the SNMP
    EngineID to be used for the contextEngineID.  Not negotiating this
    would require administrators to hand-populate management stations
    with context engine IDs in addition to ip addresses, etc.
    Currently, applications get around this when using USM by assuming
    that the negotiated security engine ID should be the default
    context engine ID to use unless the user has directly specified a
    different one to use.

(4) Ken Hornstein's KSM proposal negotiates this (in a yet-unpublished
    version of the draft).  It's not a part of kerberos, but part of
    how kerberos is used in the model.

(5) TLS doesn't provide generic negotiation so any negotiation would
    have to happen in the draft defining how TLS was to be used.  It
    would likely have to happen *after* tls got started.

(6) There is work that has been done to make TLS work over UDP:

    "Datagram Transport Layer Security", Eric Rescorla, 13-Jan-04,
    <draft-rescorla-dtls-00.txt>

    It's not standardized yet though.  see (7) below as well.

(8) The session keys are randomly generated, but enclosed in the
    tickets which are encrypted with the host and client secret keys
    which are long lived.  If those are compromised then all previous
    traffic is also compromised if it was kept because the session
    keys can be extracted at any time after the host/client keys are broken.

(9) SBSM provides true reordering protection if you set a sequence
    window size of 1, otherwise its a configurable level of reordering
    support.

-- 
Wes Hardaker
Sparta

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From: "Randy Presuhn" <[email-masked]>
Date: Thu, 14 Oct 2004 15:25:12 -0700

Hi -

> From: "Wes Hardaker" <[email-masked]>
> To: "Juergen Quittek" <[email-masked]>
> Cc: <[email-masked]>
> Sent: Thursday, October 14, 2004 1:09 PM
> Subject: Re: [Isms] selection criteria for ISMS proposals
...
> yet... We only have EUSM and SBSM responses so far?).
...

I also have seen no interest in MIASMA, so I haven't been planning
to submit it.  (Just in case there was any question.)

Randy