Re: [TLS] (crypto agility may benefit from private extensions) Re: Additional changes for draft-ietf-tls-iana-registry-updates

On Tue, Mar 20, 2018 at 5:06 PM, Rene Struik <rstruik.ext@gmail.com> wrote:

> Hi Eric:
>
> I may have an incorrect impression about the code points, but, let us say,
> one finds out an attack on one of the TLS1.3 algorithms and wishes to swap
> the algorithm set for a new one (that is clearly specified, say,
> "RS-Alg-X"). How does one do this if one marks 224-255 as deprecated.
>

I don't understand the question. There are plenty of other code points, we
just no longer break them up into signature/hash pairs.

> How does one signal private use of "RS-Alg-X" now.
>

You publish a specification that meets the specification bar and file for a
code point.

-Ekr

> If you could tell me, please let me know, so that I feel more at ease with
> this. {This should not be something where reliability is impossible to
> achieve).
>

> Thanks!
>
> Rene
>
> > One further point brought out in discussions with Adam was that if we’re
> really closing the HashAlgorithm and SignatureAlgorithms registry we need
> to also mark 224-255 as deprecated.  Currently these are marked as Reserved
> for Private Use.  So the question is should we mark 224-255 as deprecated
> in these two registries?
>
> On 3/20/2018 10:54 AM, Eric Rescorla wrote:
>
>
>
> On Tue, Mar 20, 2018 at 2:51 PM, Rene Struik <rstruik.ext@gmail.com>
> wrote:
>
>> Hi Sean:
>>
>> Quick question: does "closing the registry" not contradict catering
>> towards crypto agility? What happens if, say, one wishes to add another
>> signature scheme, besides Ed25519, to the mix. If there is no private
>> field, does this mean that, e.g., Schnorr+BSI Brainpool256r1 is now ruled
>> out?
>>
>
> No. Private just means "we're not going to allocate these code points, so
> you should use them without coordination".
>
> The key point here is that this is a big space and so we're instead going
> to make it easy for people to reserve code points by writing a stable spec,
> that need not be an IETF standard, and that's what they should do.
>
>
> -Ekr
>
>
>>
>> My more serious concern is, however, that if the Private Use case is
>> "verboten", there is no chance for people to signal private extensions
>> (since IETF will just have killed this off).
>>
>> I do not think it is prudent to have a slow process in place (IETF
>> standardization) to effectuate crypto agility, if private use can already
>> do this without waiting for 3-year public discussions and heated debate (if
>> a weakness is discovered, dark forces will exploit this right away and
>> won't wait for IETF to catch up to exploit an issue).
>>
>> As case in point, suppose US Gov't wants to roll its own "Suite A"
>> scheme, or if one wants to use TLS with something tailored towards the
>> sensor world (which operates in quite a hostile environment for
>> implementation security), how is one going to do this in context of TLS if
>> the signaling required has just been removed?
>>
>> NOTE: this is not an invite for endless discussions on the legitimacy of
>> whoever may wish a private extensions (it is private after all), it does
>> question though the wisdom of removing the option for using this. If Zulu
>> hour arrives, one should have tools to act...
>>
>> Best regards, Rene
>>
>> On 3/16/2018 10:01 AM, Sean Turner wrote:
>> > During Adam Roach’s AD review of draft-ietf-tls-tls13, he noted
>> something about the HashAlgorithm and that made me go look at what was said
>> in draft-ietf-tls-iana-registry-updates.  Turns out that 4492bis
>> assigned some values draft-ietf-tls-iana-registry-updates was marking as
>> reserved.  I have fixed that up in:
>> > https://github.com/tlswg/draft-ietf-tls-iana-registry-updates/pull/65
>> >
>> > One further point brought out in discussions with Adam was that if
>> we’re really closing the HashAlgorithm and SignatureAlgorithms registry we
>> need to also mark 224-255 as deprecated.  Currently these are marked as
>> Reserved for Private Use.  So the question is should we mark 224-255 as
>> deprecated in these two registries?
>> >
>> > spt
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>>
>>
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>>
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>
>
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