Policy 2.5 Proposal: Remove BR duplication: reasons for revocation

[Gervase Markham]

Section 6 of the Root Store Policy gives a list of reasons for
revocation, as do the BRs. The BRs list is somewhat more comprehensive
than ours; ours may be an earlier version of theirs.

We should remove the duplication by referencing the list in the BRs and
add any extra ones we might need, bearing in mind that the BRs are only
for TLS/SSL certificates, and our policy also covers S/MIME.

Our existing list rather assumes SSL certificates (e.g. bullet 5). I
can't think of any extra ones to add above and beyond those listed.

So, proposed new text:

"CAs MUST revoke Certificates that they have issued upon the
occurrence of any event listed in the appropriate subsection of section
4.9.1 of the Baseline Requirements (for email certificates, not
including those events specific to the inclusion of Domain Names)."

Are there any circumstances under which Mozilla should require
revocation which are not among those listed in the BRs?

This is: https://github.com/mozilla/pkipolicy/issues/14

-------

This is a proposed update to Mozilla's root store policy for version
2.5. Please keep discussion in this group rather than on Github. Silence
is consent.

Policy 2.4.1 (current version):
https://github.com/mozilla/pkipolicy/blob/2.4.1/rootstore/policy.md
Update process:
https://wiki.mozilla.org/CA:CertPolicyUpdates

[Jakob Bohm]

On 20/04/2017 15:46, Gervase Markham wrote:
> Section 6 of the Root Store Policy gives a list of reasons for
> revocation, as do the BRs. The BRs list is somewhat more comprehensive
> than ours; ours may be an earlier version of theirs.
>
> We should remove the duplication by referencing the list in the BRs and
> add any extra ones we might need, bearing in mind that the BRs are only
> for TLS/SSL certificates, and our policy also covers S/MIME.
>
> Our existing list rather assumes SSL certificates (e.g. bullet 5). I
> can't think of any extra ones to add above and beyond those listed.
>
> So, proposed new text:
>
> "CAs MUST revoke Certificates that they have issued upon the
> occurrence of any event listed in the appropriate subsection of section
> 4.9.1 of the Baseline Requirements (for email certificates, not
> including those events specific to the inclusion of Domain Names)."
>

Note that some reasons applicable to domain names would be equally
applicable to the domain name part of e-mail addresses. For example,
if Company X looses "ownership" of domain example.com, this should have
equal effect on TLS certificates for www.example.com and e-mail
certificates for f...@example.com.

Extend this as applicable to other domain related situations.

> Are there any circumstances under which Mozilla should require
> revocation which are not among those listed in the BRs?
>

How about this: If the operator/"owner" of the e-mail domain informs
the CA that the certificate holder has lost its rights to the specific
e-mail address under that domain?

> This is: https://github.com/mozilla/pkipolicy/issues/14
>


Enjoy

Jakob
--
Jakob Bohm, CIO, Partner, WiseMo A/S. https://www.wisemo.com
Transformervej 29, 2860 Søborg, Denmark. Direct +45 31 13 16 10
This public discussion message is non-binding and may contain errors.
WiseMo - Remote Service Management for PCs, Phones and Embedded

[Gervase Markham]

On 20/04/17 15:10, Jakob Bohm wrote:
> Note that some reasons applicable to domain names would be equally
> applicable to the domain name part of e-mail addresses.

So can you read section 4.9.1 of the BRs and help me to define wording
which excludes the irrelevant items while including all the relevant
ones? I was particularly thinking of, if memory serves, 4.9.1.1 bullets
4 and 5, both of which use the defined term "Domain Name".

Gerv

[Ryan Sleevi]

Gerv,

I must admit, I'm not sure I understand what you consider irrelevant
reasons for 4.9.1 in the context of e-mail addresses.

The only one I can think of is
"7. The CA is made aware that a Wildcard Certificate has been used to
authenticate a fraudulently misleading
subordinate Fully-Qualified Domain Name;"

But that's because such e-mail CAs are effectively wildcards (e.g. they can
issue for subdomains, unless a nameconstraint includes a leading . to
indicate for host not domain)

But given that e-mail addresses include Domain portions (after all, that is
the definition, localpart@domain), and Fully-Qualified Domain Name doesn't
imply a sAN of type dNSName, this all seems... ok as is?

[Jakob Bohm]

On 20/04/2017 21:15, Ryan Sleevi wrote:
> Gerv,
>
> I must admit, I'm not sure I understand what you consider irrelevant
> reasons for 4.9.1 in the context of e-mail addresses.
>
> The only one I can think of is
> "7. The CA is made aware that a Wildcard Certificate has been used to
> authenticate a fraudulently misleading
> subordinate Fully-Qualified Domain Name;"
>
> But that's because such e-mail CAs are effectively wildcards (e.g. they can
> issue for subdomains, unless a nameconstraint includes a leading . to
> indicate for host not domain)

I believe this is about end certificates, not constrained Intermediary
CA certificates.

>
> But given that e-mail addresses include Domain portions (after all, that is
> the definition, localpart@domain), and Fully-Qualified Domain Name doesn't
> imply a sAN of type dNSName, this all seems... ok as is?
>

Technically, the part after the @ could also be a bang!path, though
this is rare these days.

So maybe some wording in the Mozilla e-mail end cert requirements for
how the phrase "Domain Name" in the TLS cert BRs maps to rfc822-names.

[Ryan Sleevi]

On Thu, Apr 20, 2017 at 6:15 PM, Jakob Bohm via dev-security-policy <
dev-secur...@lists.mozilla.org> wrote:
>
> Technically, the part after the @ could also be a bang!path, though
> this is rare these days.
>

No, technically, it could not.

RFC 5280, Section 4.2.1.6. Subject Alternative Name
When the subjectAltName extension contains an Internet mail address,
the address MUST be stored in the rfc822Name. The format of an
rfc822Name is a "Mailbox" as defined in Section 4.1.2 of [RFC2821].
A Mailbox has the form "Local-part@Domain". Note that a Mailbox has
no phrase (such as a common name) before it, has no comment (text
surrounded in parentheses) after it, and is not surrounded by "<" and
">". Rules for encoding Internet mail addresses that include
internationalized domain names are specified in Section 7.5.

Note that RFC 2821 was OBSOLETEd by RFC 5321. RFC 5321 Section 4.1.2 states

Mailbox = Local-part "@" ( Domain / address-literal )
address-literal = "[" ( IPv4-address-literal /
IPv6-address-literal /
General-address-literal ) "]"
; See Section 4.1.3
Domain = sub-domain *("." sub-domain)
sub-domain = Let-dig [Ldh-str]
Let-dig = ALPHA / DIGIT
Ldh-str = *( ALPHA / DIGIT / "-" ) Let-dig

Section 4.1.3 states
IPv4-address-literal = Snum 3("." Snum)
IPv6-address-literal = "IPv6:" IPv6-addr
General-address-literal = Standardized-tag ":" 1*dcontent
Standardized-tag = Ldh-str
; Standardized-tag MUST be specified in a
; Standards-Track RFC and registered with IANA

To confirm, I also checked the IANA registry established, which is
https://www.iana.org/assignments/address-literal-tags/address-literal-tags.xhtml

The only address literal defined is IPv6.

Could you indicate where you believe RFC 5280 supports the conclusion that
a "bang!path" is permitted and relevant to Mozilla products?

[Jakob Bohm]

The older RFC 2459 allowed the full RFC 822 syntax (minus comments),
which included bang paths. While RFC 2459 and RFC 822 are obsolete, it
is still possible, sans explicit policy to the contrary, for a CA to
issue valid certificates for this older address type, perhaps as a
service to someone running historic system configurations.

Even them, I think wording is still needed to state that the
"domain"/"address-literal" part of the RFC5321 syntax is the part to
which the "domain name" revocation BRs apply.

Plus there is the additional situation of an e-mail domain
operator/owner telling a CA that an e-mail cert should be revoked for
various reasons (misissued cert, misissued e-mail address, e-mail
address removed from cert holder, possibly others).

[Gervase Markham]

On 20/04/17 14:46, Gervase Markham wrote:
> So, proposed new text:
>
> "CAs MUST revoke Certificates that they have issued upon the
> occurrence of any event listed in the appropriate subsection of section
> 4.9.1 of the Baseline Requirements (for email certificates, not
> including those events specific to the inclusion of Domain Names)."

Edit made as follows:

"CAs MUST revoke Certificates that they have issued upon the occurrence
of any event listed in the appropriate subsection of section 4.9.1 of

the Baseline Requirements, according to the timeline defined therein."

I added the note about timeline because it's possible that the Forum may
be updating those rules soon to be a bit more flexible, and I wouldn't
want it to seem like the Mozilla policy requires immediate revocation.

Gerv