[Servercert-wg] SCXX Ballot - Debian Weak Keys (and related vulnerabilities)

Fri Jul 8 16:43:51 UTC 2022

It seems to me like the appropriate line to walk would be:
First, state the requirements (such as blocking debian weak keys, or
blocking ROCA keys) in plain language, much as the current ballot does.
This makes the requirement that CAs must abide by clear.
Second, provide links to tools that may be helpful. Do not preface these
links with any normative language, i.e. say "CAs may find these tools
useful: ...", not "CAs MAY use these tools: ...". This serves the purpose
of providing easy access to the helpful external resources, but without
stating that their contents have been vetted and fully approved.

Does that makes sense?
Aaron

On Fri, Jul 1, 2022 at 12:13 PM Chris Kemmerer via Servercert-wg <
servercert-wg at cabforum.org> wrote:

> *INTRO*
>
> Thanks to all who participated in the very useful discussion regarding
> this proposed ballot in our June 23 2022 call.
>
> An important point was raised about how to handle external links to
> recommended (but not required) resources. In "Section 6.1.1.3. Subscriber
> Key Pair Generation" of the proposed language, we require CAs to reject
> requests for certificates with "industry demonstrated weak Private Keys"
> (as "SHALL" and "MUST" directives), then provide links to "Suggested tools
> that CAs MAY use" to judge requests.
>
> *THE QUESTIONS*
>
> The questions here are:
>
>    - *If we direct issuers to external resources in CABF documents, what
>    level of CABF-level vetting should be required or expected for those links?*
>    - And* is the ballot process itself sufficient vetting for such links?*
>
> *OUR ASSUMPTION AND EXISTING LINKS*
>
> We are assuming that for, weak key detection, we DO want to provide useful
> links to help guide certificate issuers (see sidebar below). Note that the
> current BR language already includes one such link, to a page maintained by
> Debian (https://wiki.debian.org/SSLkeys), though with a vetted status
> unknown to us.
>
> Our proposed ballot language also adds a requirement to reject keys
> "identified by the tools available at https://github.com/crocs-muni/roca
> or equivalent". As we recall it, this resource was suggested by a CABF
> participant now departed, and again the status of vetting for this link is
> unknown.
>
> For what it's worth, a quick scan of the BRs shows that, apart from weak
> key guidance, we do include links to other external resources which are
> presumably foundational enough to not require vetting. These include:
>
>    - IETF (various RFCs, ex. http://tools.ietf.org/html/rfc5890)
>    - IANA (registry information, ex.
>    https://www.iana.org/assignments/iana-ipv4-special-registry/iana-ipv4-special-registry.xhtml
>    )
>    - NIST (publications, ex.
>    http://csrc.nist.gov/publications/nistpubs/800-89/SP-800-89_November2006.pdf
>    )
>    - and the Mozilla Foundation (the Public Suffix List,
>    https://publicsuffix.org/).
>
> *"CROSS-VETTING" OF PROPOSED RESOURCES*
>
> As Dimitris stated in the call, the two other links included as resources
> which MAY be utilized:
>
>    - https://github.com/CVE-2008-0166
>    - https://github.com/HARICA-official/debian-weak-keys
>
> ... have been "cross-vetted" by their respective providers (HARICA and
> Sectigo).
>
> This discussion was spurred by a suggestion from Adriano Santoni to
> consider adding a third resource (Hanno Böck's badkeys tool):
>
>    - https://github.com/badkeys/badkeys (web version:
>    https://badkeys.info/)
>
> ...for which no such CABF-level "cross-vetting" has been performed (as far
> as we know).
>
> We ourselves very much appreciate the effort that went into creating these
> tools and intend to utilize them. However:
>
> *TO RESTATE THE QUESTIONS*
>
>    - *Is the ballot process itself considered adequate vetting for
>    external links in CABF documents?*
>    - If not, *what vetting would we consider adequate?*
>
> *SIDEBAR: OTHER OPTIONS*
>
>    - In the June 23 call, an external, CABF-supported resource (i.e. a
>    separate web page with appropriate links) was considered, discussed, and
>    rejected as likely to increase overhead and decrease reliability. Based on
>    this, our sense is that *any links deemed useful should indeed be
>    included in the actual ballot language itself*.
>    - And finally, as raised in previous discussions: *Would some sort of
>    disclaimer be appropriate for external links*, and if so should it
>    extend beyond the 6.1.1.3 links to cover external resources more generally?
>
> *CLOSING REMARKS*
>
> Thanks.
> ------------------------------
> *From:* Servercert-wg <servercert-wg-bounces at cabforum.org> on behalf of
> Adriano Santoni via Servercert-wg <servercert-wg at cabforum.org>
> *Sent:* Sunday, June 12, 2022 7:11 PM
> *To:* servercert-wg at cabforum.org <servercert-wg at cabforum.org>
> *Cc:* Hanno Böck <hanno at hboeck.de>
> *Subject:* Re: [Servercert-wg] SCXX Ballot - Debian Weak Keys (and
> related vulnerabilities)
>
>
> Might a third option be the tool developed by Hanno Boeck?
>
> https://github.com/badkeys/badkeys
> <https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fbadkeys%2Fbadkeys&data=05%7C01%7Cchris%40ssl.com%7C8641292420c44f04613b08da4cd14ed0%7C7741372af1ae4cc7b93ce6c2c138b2bb%7C0%7C0%7C637906759104963939%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=DwRmkMHaKGp4rQDSPpbekE%2B5MwXinAtDIPExqNT4yZ0%3D&reserved=0>
>
> From our point of view it's an effective tool.
>
> Adriano
>
>
> Il 09/06/2022 15:18, Chris Kemmerer via Servercert-wg ha scritto:
>
> Suggested tools that CAs MAY use to obtain lists of Debian weak keys
> include:
>
>   - https://github.com/CVE-2008-0166
> <https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FCVE-2008-0166&data=05%7C01%7Cchris%40ssl.com%7C8641292420c44f04613b08da4cd14ed0%7C7741372af1ae4cc7b93ce6c2c138b2bb%7C0%7C0%7C637906759104963939%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=zfjpsiplLaqFzwkKzciu7cQTRzDeeqBP0XFs3zn5OJg%3D&reserved=0>
> provides a generator, for the complete set of parameters listed above, that
> runs on any modern 64-bit Linux system; it also provides complete sets of
> pregenerated keys for the most common RSA key sizes.
>   - https://github.com/HARICA-official/debian-weak-keys
> <https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FHARICA-official%2Fdebian-weak-keys&data=05%7C01%7Cchris%40ssl.com%7C8641292420c44f04613b08da4cd14ed0%7C7741372af1ae4cc7b93ce6c2c138b2bb%7C0%7C0%7C637906759104963939%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=JAHix0XFgxltAzN0FGh58bZkHVRLacTP8rUK35Ymn0c%3D&reserved=0>
> provides a generator, for a subset of the parameters listed above, that can
> take advantage of a computer cluster.
>
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