In message <alpine.deb.2.11.1707292141070.23...@grey.csi.cam.ac.uk>, Tony Finch
writes:
> I think I have spotted a lacuna or possibly erratum in RFC 7344.
>
> In section 4.1 bullet 2 it says:
>
> o Signer: MUST be signed with a key that is represented in both the
> current DNSKEY and DS RRsets, unless [unusual case]
It just means that signers that know about ksk/zsk have special rules
for cds and cdnskey. This is from BIND's dnssec-signzone and causes
the cds and cdnskey rrsets to be signed with both ksk and zsk dnskeys.
} else if (set->type == dns_rdatatype_cds ||
set->type == dns_rdatatype_cdnskey ||
iszsk(key)) {
> This allows a setup where
>
> * the DNSKEY RRset contains a ZSK and a KSK
>
> * the DNSKEY RRset is signed by the KSK (of course)
>
> * the CDS and CDNSKEY RRsets are signed by the ZSK (weirdly)
>
> * the parent contains DS records corresponding to both the KSK (of
> course) and the ZSK (weirdly)
>
> In this weird setup the ZSK's DS can't authenticate the delegation (per
> RFC 4035 section 5.2) but it does authenticate the CDS/CDNSKEY RRsets.
>
> Is this intended?
The purpose was for the CDS/CDNSKEY tools to not have to fetch the
current DNSKEY RRset to be able to validate the records provided they
have a current KSK.
> Or was RFC 7344 supposed to say something like:
>
> o Signer: MUST be signed with a DNSKEY RR that authenticates the
> delegation as described in RFC 4035 section 5.2 or any subsequent
> updates, unless [unusual case]
>
> One particularly relevant update is RFC 4509 which has extra requirements
> about ignoring SHA-1 DS records if SHA-2 records are present. Should this
> check also apply to CDS / CDNSKEY RRsets?
>
> Tony.
> --
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