Subject: Re: Terminology question: "suites" vs "set of cryptographic algorithms"

From: Paul Hoffman / VPNC <[email-masked]>
Date: Fri, 2 May 2003 16:40:30 -0700

The term "suite" is used inconsistently in the current document. In 
some places, it means "the set of things chosen by the responder". 
However, there are exceptions. I have listed what I think are the 
main problems with the term "suite" in the current draft.

The third paragraph of 2.7 says:
    This hierarchical structure was designed to be able to efficiently
    encode proposals for cryptographic suites when the number of
    supported suites is large because multiple values are acceptable for
    multiple transforms. The responder MUST choose a single suite, which
    MAY be any subset of the SA proposal following the rules below:
This use of "suites" is talking about the proposals offered by the 
initiator, which is the "old" use of suites.

The last sentence in 2.7 says:
    Alice MUST again propose her full
    set of acceptable cryptographic suites because the rejection message
    was unauthenticated and otherwise an active attacker could trick
    Alice and Bob into negotiating a weaker suite than a stronger one
    that they both prefer.
But Alice isn't proposing suites, she is proposing individual algorithms.

In 3.10.1 it says:
         NO_PROPOSAL_CHOSEN                       14
             None of the proposed crypto suites was acceptable.
But no suites were proposed: algorithm choices were proposed.

Section 6:
    Values of the Cryptographic Suite-ID define a set of cryptographic
    algorithms to be used in an IKE, ESP, or AH SA.
We removed Suite-ID completely.

Appedix B:
    Future IANA-registered and private use Suite-IDs MAY use Diffie-
    Hellman groups that have modulus values and generators that are
    different than those in this document or in [ADDGROUP].
Ditto.

--Paul Hoffman, Director
--VPN Consortium

---

From: [email-masked]
Date: Fri, 9 May 2003 23:33:11 -0400

Paul Hoffman / VPNC <[email-masked]> wrote on 05/02/2003 07:40:30
> main problems with the term "suite" in the current draft.
I've tried to use it to mean "a collection of algorithms used together
in an SA". The initiator proposes multiple suites (not as a list, but
as a Chinese menu (I hope that term has not become politically
incorrect)), and the responder selects one.

To clarify this, I changed the third paragraph of IKE Protocol Overview to
the following:

IKE performs mutual authentication between two parties and establishes
an IKE security association that includes shared secret information
that can be used
to efficiently establish SAs for ESP [RFC2406] and/or AH [RFC2402] and
a set of cryptographic algorithms to be used to protect the SAs.
In this document, the term "suite" or "cryptographic suite" refers to
a complete set of algorithms used to protect an SA. An initiator
proposes one or more suites by listing supported algorithms that can
be combined into suites in a mix and match fashion.
IKE can also negotiate use of IPcomp
[RFC2393] in connection with an ESP and/or AH SA.
We call the IKE SA an "IKE_SA". The SAs for ESP and/or AH
that get set up through that IKE_SA we call "CHILD_SA"s.

Does that help?

> initiator, which is the "old" use of suites.
This seems clear to me. Do you have an alternate wording to propose?

> But no suites were proposed: algorithm choices were proposed.
Likewise, these seem clear to me; do you have an alternate wording.

> We removed Suite-ID completely.
You're right on this one. It's an obsolete reference. I removed it.

>     different than those in this document or in [ADDGROUP].
This is also obsolete, and I removed it.

Was there ever a declared consensus on whether the algorithm definitions
(including all of Appendix B) should be removed so as not to duplicate
information in the algorithms document?

Barbara? Ted?

> --VPN Consortium

      --Charlie