Re: [secdir] dir review of draft-laurie-pki-sunlight-05

Tobias Gondrom <> Sat, 09 February 2013 13:35 UTC

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Date: Sat, 09 Feb 2013 21:34:53 +0800
From: Tobias Gondrom <>
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Subject: Re: [secdir] dir review of draft-laurie-pki-sunlight-05
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Hi Ben,

I also just read through your draft in version -07.
I can see the draft consists of two parts:
1. data structure
2. protocol.

For part #1 the data structure: in case you are not aware of it, some
years ago the IETF LTANS WG has done something a bit similar in a more
generic way (i.e. for any data not only for certificates) in form of
RFC4998 and RFC6283 with a number of implementations by major ECM and
DMS vendors.
Just as a thought, maybe helpful looking at or even for re-use instead
of re-inventing the wheel?

Best regards, Tobias

On 30/01/13 18:15, Ben Laurie wrote:
> On 29 January 2013 21:28, Jeffrey Hutzelman <> wrote:
>> On Tue, 2013-01-29 at 11:35 +0000, Ben Laurie wrote:
>>> On 24 January 2013 19:06, Jeffrey Hutzelman <> wrote:
>>>> Similarly, as an anti-spam measure, this document proposes that logs accept
>>>> only certificates which chain back to a known CA, and requires that logs
>>>> validate each submitted certificate before appending it to the log.  This
>>>> sounds good, but it's not the only possible mechanism, and so I think MUST
>>>> is too strong here.  Additionally, there is no discussion of the security
>>>> implications if a client depends on a log to do this and the log does not
>>>> actually do so.  Rather than requiring that logs validate every submitted
>>>> certificate, the document should only RECOMMEND that they do so, and make
>>>> clear that clients MUST NOT depend on such validation having been done.
>>> On second thoughts, whilst that is an effective anti-spam measure, it
>>> is also part of the functionality of CT: i.e. to identify misissue and
>>> give some means to do something about it. The CA check ensures we have
>>> someone to blame for misissue.
>> Hrm.  I sort of thought the idea was for the logs to be untrusted
>> repositories, able to be audited but not themselves expected to detect
>> problems.  If logs are expected to do validation of this sort, is there
>> a way for a third party to discover whether they are doing so (or at
>> least, whether they are accepting certificates they shouldn't)?
> A third party can indeed verify this - they just watch the log like
> any monitor does.
>>> I am not averse to suggestions that achieve the overall aim, but I
>>> don't see the virtue of leaving it vague in the description of the
>>> experiment we are actually running.
>> I'm not suggesting vagueness; rather, I'm merely suggesting downgrading
>> a MUST to a SHOULD, which is still quite strong.  What happens if
>> someone wants to start logging certs issued by a private CA, or
>> self-signed certs they have observed, or...?
> I don't see an issue with logging certs from a private CA. As for
> self-signed certs, I don't see the point, but I guess if someone
> figures out a point we can relax it in the next version.
>> I'm suppose I'm OK with keeping the scope narrower than that for
>> purposes of the experiment, as long as it is possible to relax the
>> requirement later without breaking the system.  Hence the importance of
>> making it clear that clients must not rely on logs to have done
>> validation (on which point I think we've already reached agreement).
> Cool.
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