Subject: [babel] rfc6126bis security implementation requirements

From: Donald Eastlake <[email-masked]>
Date: Fri, 9 Nov 2018 23:17:05 -0500

In discussion at the BABEL WG meeting in Bangkok, there appeared to be
consensus in the room that rfc6126bis should normatively reference both the
hmac and the dtls Babel security drafts and should recommend implementing
both. It should also recommend using hmac unless the additional security
features of dtls are specifically needed. Neither would be mandatory to
implement. This email is to confirm that consensus.

If you have any opinion on this, please reply within the next week or two.

Thanks,
Donald
===============================
 Donald E. Eastlake 3rd   +1-508-333-2270 (cell)
 1424 Pro Shop Court, Davenport, FL 33896 USA
 [email-masked]

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From: Toke Høiland-Jørgensen <[email-masked]>
Date: Sat, 10 Nov 2018 10:21:24 +0100

Donald Eastlake <[email-masked]> writes:

> consensus in the room that rfc6126bis should normatively reference
> both the hmac and the dtls Babel security drafts and should recommend
> implementing both. It should also recommend using hmac unless the
> additional security features of dtls are specifically needed. Neither
> would be mandatory to implement. This email is to confirm that
> consensus.

Sounds good to me :)

-Toke

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From: Juliusz Chroboczek <[email-masked]>
Date: Sat, 10 Nov 2018 12:56:29 +0100

> hmac and the dtls Babel security drafts and should recommend implementing both.
> It should also recommend using hmac unless the additional security features of
> dtls are specifically needed. Neither would be mandatory to implement. This
> email is to confirm that consensus.

I think that what we agreed about is that Babel-HMAC is recommended, both
for implementation and deployment, and that we (as a group) hold no
opinion on Babel-DTLS.

The reason we don't want to recommend implementing Babel-DTLS is that it
is not necessarily trivial to implement: it requires a fair amount of
hacking to get an implementation to speak unicast, and it imposes
a dependency on a DTLS stack.

Thus, I think that recommending implementation of Babel-DTLS might reduce
the applicability of Babel.  Let's recommend Babel-HMAC, and let the
market choose whether to implement Babel-DTLS.

-- Juliusz

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From: Donald Eastlake <[email-masked]>
Date: Sun, 11 Nov 2018 03:37:27 -0500

Hi Juliusz,

A recommendation can be pretty weak depending on what you say about when it
might not be applicable. Let's see if anyone else has comments on this.

Thanks,
Donald

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From: Toke Høiland-Jørgensen <[email-masked]>
Date: Sun, 11 Nov 2018 09:41:04 +0100

Donald Eastlake <[email-masked]> writes:

> Hi Juliusz,
>
> A recommendation can be pretty weak depending on what you say about
> when it might not be applicable. Let's see if anyone else has comments
> on this.

Well for my part, I read "recommend both" as "great, I can continue to
not implement DTLS". :)

Don't have any strong opinion on the wording, though...

-Toke

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From: "Russ White" <[email-masked]>
Date: Sun, 11 Nov 2018 06:46:36 -0500

> when it might not be applicable. Let's see if anyone else has comments on
> this.

If we need to mention something, then I would make it a "MAY," so that folks know it's out there. It might be worth building an appendix someplace explaining why this is difficult?

😊 /r

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From: Juliusz Chroboczek <[email-masked]>
Date: Fri, 16 Nov 2018 14:06:57 +0100

> If we need to mention something, then I would make it a "MAY," so that
> folks know it's out there.  It might be worth building an appendix
> someplace explaining why this is difficult?

I think that David and Antonin have done a good job in the Applicability
section of Babel-DTLS.  I'd rather not litter 6126bis with this kind of
considerations, it's grown too much already since 6126.

(Please review the Applicability section of Babel-DTLS, and tell us if
that's good enough.)

-- Juliusz

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From: Juliusz Chroboczek <[email-masked]>
Date: Fri, 16 Nov 2018 14:18:46 +0100

> Well for my part, I read "recommend both" as "great, I can continue to

I take this to mean that you agree with me in principle...

> Don't have any strong opinion on the wording, though...

...but think I'm being overly pedantic.  (You probably have a stronger
expression in mind.)

As to implementing Babel-DTLS or not: the bet we're making with Babel-HMAC
is that people don't actually need asymmetric auth or confidentiality, and
that they'll be happy enough with the deliberately minimal features provided
by Babel-HMAC.

I like to think of Babel-DTLS as our insurance in case we lose the bet.
(David and Antonin might see things differently.)

-- Juliusz

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From: Toke Høiland-Jørgensen <[email-masked]>
Date: Fri, 16 Nov 2018 11:29:59 -0800

> I take this to mean that you agree with me in principle...

Yup.

> ...but think I'm being overly pedantic.  (You probably have a stronger

I'm fine with the text in -07.

-Toke