Re: FUD about CGD and GBDE

From: Poul-Henning Kamp (phk_at_phk.freebsd.dk)
Date: 03/03/05

  • Next message: Poul-Henning Kamp: "Re: FUD about CGD and GBDE" 
    To: "Perry E. Metzger" <perry@piermont.com>
Date: Thu, 03 Mar 2005 22:08:46 +0100

    In message <87ekewjxp4.fsf@snark.piermont.com>, "Perry E. Metzger" writes:

    >> There is a world out here that's called the IT industry.
    >
    >Yes, there is. They routinely deploy bad security because they don't
    >get people who know what they are doing involved. See WEP, for
    >example, or a thousand other things.

    Yes, it would really be desirable for the cryptographers to come
    down from their mount olympus more often. Too bad they never
    answer invitations :-(

    >I have no idea what you're talking about,

    Thanks for confirming what I wrote just a second ago above.

    >If you're talking about MD5 which is used in many modern Unixes, it
    >was done by Ron Rivest, and even though he's really good, it has
    >recently been (quite badly) broken.

    Again.

    >> At the time where I wrote GBDE, the best that was offered was CGD (and
    >> similar) and users (not cryptographers!) didn't trust it and history
    >> have so far repeated.
    >
    >I have no idea what you are talking about here.

    And again.

    >> I can add another property of the elite society of cryptographers:
    >> if you are not a card carrying member of their society, the majority
    >> of their members can not even be bothered to reply to an email from
    >> an outsider. This does hamper communiation a bit.
    >
    >Actually, you can show up at any crypto conference you like,

    I have a better idea: Why don't we get the cryptographers to
    show up at computer science conferences ? That would get the
    gospel out to a far wider crowd without spoiling the highly
    specialized conferences for the cryptographers.

    >> Maybe the problem is that cryptographers, like true computer
    >> scientists, write in nothing less portable than pencil number two ?
    >
    >It is rare to see a new algorithm show up from someone like Ron Rivest
    >without some C code also appearing. That's pretty common in the crypto
    >world. When the Chinese team that cracked a bunch of hash algorithms
    >last summer presented their work, they had worked examples of their
    >stuff.

    You seem to misunderstand something: Computer users don't call MD5
    directly. They use software which makes the calls for them. Sometimes
    this software has a goal which is different from calling crypto
    algorithms, in fact some of them even have the impropiety of
    regarding the crypt algorithms as mere tools.

    >I think you don't quite get it the point.

    There are many points not being got here.

    >1) No one claims that you need to be a cryptographer to write
    > something like GBDE. What is being claimed is that you should not
    > have invented your own cryptographic modes, and that you might have
    > wanted to ask some professionals about your approach.

    You have not actually studied GBDE yet, right ? You don't actually
    know if I invented my own "cryptographic modes" or not, do you ?

    >2) CGD *has* been looked at by a bunch of people, and was written to
    > carefully use standard algorithms in a standard way. If you don't
    > like using NetBSD code because NetBSD people have cooties, fine --
    > I don't care, write your own. However, you should at least pay the
    > same attention to conservative use of cryptographic algorithms and
    > having people review your work is a good idea, too.

    Even if I were alone in the world with the sentiment, I would never
    call CGDs use of the same key for all sectors "conservative".

    >3) You've made some very bizarre claims about the security of your
    > system. Some of these claims have already been shown on their face
    > to be incorrect, such as your claimed work factor for breaking your
    > new "improved" crypto modes.

    Sorry, they have only been disproved in a significantly larger universe
    than the one my users inhabit. That doesn't count to me.

    > Instead, he admitted his mistakes and wrote a version 2.

    Any qualified, factually correct critique of GBDE will be taken very
    serious by me. I am very much looking forward to it. What Roland
    has provided is not it.

    > Are your users better served by you digging in your heels and
    > saying "GDBE is perfect as it is",

    Now, there is one thing I have never said and would never say. 

    -- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.
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