Re: [lamps] Draft LAMPS Recharter

[Ryan Sleevi <[e-mail]>]

On Thu, May 3, 2018 at 8:50 AM Eric Rescorla <[e-mail]> wrote:

> On Wed, May 2, 2018 at 2:06 PM, Ryan Sleevi <[e-mail]> wrote:
>
>>
>>
>> On Wed, May 2, 2018 at 10:41 AM, Russ Housley <[e-mail]>
>> wrote:
>>
>>> Based on the discussion in London and the "Potential Topics for LAMPS
>>> Recharter" mail thread.  We propose the attached charter text.  Please
>>> review and comment.
>>>
>>> Russ & Tim
>>>
>>> = = = = = = = = =
>>>
>>> 3. Specify the use of short-lived X.509 certificates for which no
>>> revocation information is made available by the Certification Authority.
>>> Short-lived certificates have a lifespan that is shorter than the time
>>> needed to detect, report, and distribute revocation information, as a
>>> result revoking them pointless.
>>>
>>
>> I didn't see much discussion on the list in support for this, but
>> apologies, I missed the discussion in SECDISPATCH when this draft was
>> discussed.
>>
>> Is this being envisioned for the use in the PKI typically called the "Web
>> PKI", or is this being seen as a draft for private use cases? I have read
>> the draft, and do not feel this was clearly and unambiguously answered.
>>
>> I ask because, for various policy reasons, I would expect that
>> undertaking this work may result in policies that explicitly prohibit it
>> from being deployed on the Web PKI.
>>
>
> Ryan,
>
> Do you think you could elaborate on this point?
>

It seems a bit less germane to discuss potential root store policy here in
the IETF, but there are already policies around lifetimes - such as maximum
certificate lifetimes or minimum OCSP response validity durations. Despite
being technically capable of issuance, I fully anticipate minimum lifetimes
being required for certificate validity.

Validity merely externalizes cost to PKI participants - too long a
validity, for example, carries greater risk of both key compromise and
information staleness. Models such as revocation try to remediate that, but
shift more burden onto relying parties. Actions such as too short validity
also shifts burden onto clients and the ecosystem - notably in terms of
client clock issues, by increasing the precision and accuracy necessary.

As it relates to the draft, however, it has further flaws in the design
assumptions, similar to these concerns. For example, suggesting that CAs
would be able to use shorter-lived certificates to no longer keep track of
what they issue is fundamentally incompatible with a Web PKI in which every
CA is accountable for what it issues: presently, for between five to seven
years from issuance. This is orthogonal to things like Certificate
Transparency, and is about operational requirements.

I expect the floor for certificates to bottom out at around 21-30 days for
publicly trusted certificates for the next decade, which potentially would
be mandated by requirements on issuance policy.

>