Hi all,

Another brief update that this ballot now passed at the CA and Browser
Forum.

Best,
Henry

On Thu, Oct 9, 2025 at 12:26 PM Aaron Gable <aaron=
[email protected]> wrote:

> Since I now realize that I forgot to say this in my previous message:
> Let's Encrypt plans to implement the server side of dns-persist in 2026. We
> believe that it will provide a real benefit to our ACME clients, especially
> in concert with the WebPKI reducing validation data reuse periods over the
> next couple years.
>
> Aaron
>
> On Thu, Oct 9, 2025 at 8:51 AM Henry Birge-Lee <birgelee=
> [email protected]> wrote:
>
>> Hi all,
>>
>> Michael Slaughter's ballot for this in the CA/Browser Forum is making
>> great progress with (what I believe is) unanimous support and sufficient
>> browser support (2 certificate consumer votes) to pass. It is likely the
>> voting (which concludes tomorrow) will pass and it will enter IP review.
>>
>> I have already gotten a commitment to implement this in private from a
>> very large ACME CA.
>>
>> Shiloh has already pushed initial test implementations for a client and a
>> CA that interoperate. (
>> https://mailarchive.ietf.org/arch/msg/acme/X7eWneZfFRk19hNg7LuITzlIlk8/
>> ) . Shiloh also represents Fastly/Certainly, another large ACME CA that
>> will very likely be implementing. Slaughter represents Amazon Trust
>> Services which I would also expect to implement. Both Amazon and Fastly
>> additionally run massive numbers of ACME clients which allows them to
>> deploy the other side of this protocol as well.
>>
>> In addition, there is a "no RFC" way of doing this in ACME which several
>> CAs have already brought to my attention: check DNS persist records in
>> advance and then provide no challenges to the ACME client if there is a
>> record. This requires no client modification but comes at a performance
>> overhead and eliminates the client's ability to choose which challenge to
>> use which is a part of the ACME protocol. If this technique is adopted in
>> production without this I-D moving forward there would be no IETF guidance
>> around this type of behavior.
>>
>> *Independent of the IETF's decision to adopt, I feel there is high
>> likelihood this technique will be used in production at several large CAs*
>> based on implementation interest I have received by various CAs and the
>> popularity of the dns-01 with CNAME technique which shows the desire for a
>> static DCV-related record. Implementation without an IETF draft would mean
>> either 1) implementation only by non-ACME CAs which gives a disadvantage to
>> the ACME protocol as there are legitimate use cases for doing this, 2)
>> implementation using the "no RFC" approach discussed above without any IETF
>> input, or 3) implementation based on a personal, non-adopted I-D. To me all
>> three of these outcomes feel subpar.
>>
>> Based on my talk at IETF 123, I had gotten the impression that the ACME
>> WG was interested in providing input on this standard and this approach
>> more generally. We felt IETF involvement would be beneficial to the
>> community which is why we brought this to the IETF. I encourage members of
>> the working group to see this as an opportunity to contribute and improve
>> on a standard that is already moving forward in other ecosystems. We want
>> to work with the IETF community and have incorporated all feedback to
>> date/are hoping for the opportunity to improve this further post adoption.
>>
>> Best,
>> Henry
>>
>>
>> On Tue, Sep 30, 2025 at 10:06 AM Michael Richardson <
>> [email protected]> wrote:
>>
>>>
>>> Henry Birge-Lee <[email protected]> wrote:
>>>     > and the acme-dns.io hosted offering of
>>> https://github.com/joohoi/acme-dns ).
>>>
>>> Oh, yes, I knew about this, but since I already had debugged nsupdate,
>>> and
>>> could copy and paste that configuration, I never returned to that.
>>>
>>>     > This approach of using a magic CNAME 1) creates a single point of
>>> failure
>>>     > where a compromise of a CNAME service (potentially over the
>>> network via DNS
>>>     > attacks like cache poisoning or BGP attacks) could take down
>>> thousands
>>>     > of
>>>
>>> DNSSEC solves some of those sins.
>>> And the auxiliary zone is much easier to DNSSEC sign.
>>>
>>>     > Another perspective to consider is that should a subscriber
>>> automate the
>>>     > dns-01 challenge, there is a risk the subscriber will put
>>> unrestricted DNS
>>>     > API keys on their ACME client. This is not an ideal security
>>> configuration
>>>     > and avoiding the need for online keys on the ACME client is
>>> generally
>>>     > beneficial for security.
>>>
>>> I'm hearing that we might need/want CSR-attestation-like mechanism for
>>> ACME account and API keys too :-)
>>>
>>> --
>>> Michael Richardson <[email protected]>   . o O ( IPv6 IøT
>>> consulting )
>>>            Sandelman Software Works Inc, Ottawa and Worldwide
>>>
>>>
>>>
>>>
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>>
>
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