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Re: Gen-ART review of draft-ietf-krb-wg-otp-preauth-18

2011-08-24 21:04:39
  <david(_dot_)black(_at_)emc(_dot_)com> writes:


    > [1] In section 6.1 at the top of p.28, I don't believe that the
    > use of lower case "recommended" is a strong enough warning about
    > the danger in using anonymous PKINIT because it exposes the OTP
    > value:

    >    It is therefore recommended that anonymous PKINIT not be used
    > with OTP algorithms that require the OTP value to be sent to the
    > KDC and that careful consideration be made of the security
    > implications before it is used with other algorithms such as those
    > with short OTP values.

    > At a minimum, that warning should be in upper-case:

    >    It is therefore RECOMMENDED that anonymous PKINIT not be used
    > with OTP algorithms that require the OTP value to be sent to the
    > KDC. In addition, the security implications should be carefully
    > considered before anonymous PKINIT is used with other algorithms
    > such as those with short OTP values.

    > Beyond that, the security issue in the first sentence may be
    > severe enough to justify a prohibition, so the following would
    > also be acceptable:

    >    Therefore anonymous PKINIT SHALL NOT be used with OTP
    > algorithms that require the OTP value to be sent to the KDC. In
    > addition, the security implications should be carefully considered
    > before anonymous PKINIT is used with other algorithms such as
    > those with short OTP values.

I definitely agree that we should use RFC 2119 language.
Note that WG participants have questioned this text in last call for
other reasons.
Many implementations use anonymous pkinit in a mode where the KDC's
certificate is verified--that is the client is anonymous but the KDC is
identified through a PKI.
WG participants believe (and I agree) that the security concern does not
apply at all in this case.
So, the text needs reworking.

    > [2] In section 5, the first paragraph in the IANA considerations
    > is unclear, and following its reference to section 4.1, I don't
    > see any clarifying text there either.  I think Sections 4.1 and
    > 4.2 need to say that the value of otp-algID is a URI obtained from
    > the PSKC Algorithm URI Registry, and the first paragraph in
    > section 5 should say that URIs for otp-algID are to be registered
    > in that registry, see RFC 6030.

Why should we require that alg-ids be registered URIs?  I.E. what is
wrong with me using
http://algorithms.painless-security.com/otp/best-thing-since-unsliced-bread
(or a tag URI if you like) for my OTP algorithm?
I have no problem with the IETF registering its algorithms there, or us
encouraging people to register them them, but it's a URI. What purpose
is served by forcing registration?
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