Hi all,
I have a question regarding processing of CAA records for “wildcard
certificates”.
Let’s assume the following CSR:
X509v3 Subject Alternative Name:
DNS: *.example.com
DNS: example.com
Per BR, every SAN DNS name must be checked separately.
Now, my interpretation would be that for *.example.com, you would query
example.com for an “issuewild" entry,
and for example.com, you would query example.com for an "issue" entry.
What if the zone file looks like this:
example.com 0 CAA 0 issue “;”
example.com 0 CAA 0 issuewild “yourca”
My interpretation would be that “yourca” (as any other CA) would not be
permitted to issue this certificate,
as it is not allowed to issue for the non-wildcard part example.com.
A plunge through the related documents [see appendix] seems to point in that
direction, but I still have doubts.
What is the community interpretation?
Kind regards
Quirin
---------
Appendix:
BR defines a wildcard certificate as "Wildcard Certificate: A Certificate
containing an asterisk (*) in the left‐most position of any of the Subject
Fully‐Qualified Domain Names contained in the Certificate.” —> This means that
the whole certificate is a wildcard certificate.
—
RFC2818:
> Names may contain the wildcard character * which is considered to match any
> single domain name component or component fragment. E.g., *.a.com matches
> foo.a.com but not bar.foo.a.com. f*.com matches foo.com but not bar.com.
—> example.com is not part of *.example.com
RFC6844:
> " issuewild <Issuer Domain Name> [; <name>=<value> ]* : The issuewild
> property entry authorizes […] to issue wildcard certificates for the
> domain in which the property is published."
> "Given a request for a specific domain X, or a request for a wildcard
> domain *.X, the relevant record set R(X) is determined as follows:”
—> The 'relevant record set' is specified per domain
> "issuewild properties MUST be ignored when processing a request for a
> domain that is not a wildcard domain."
—> Especially this last paragraph seems to indicate that the CSR above would
not be permitted to be issued. Also, it specifically uses “domain” and not
“certificate”.
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