Hi Mike,

On 8/10/24 17:21, Michael StJohns wrote:
Paul - this is related directly to the newly specified inclusion of the public 
key material in this draft (sect 3.2 last para):

    A KeyDigest element can contain both a Digest and a publickeyinfo
    named pattern.  If the Digest element would not be a proper DS record
    for a DNSKEY record represented by the publickeyinfo named pattern,
    relying parties MUST NOT use that KeyDigest as a trust anchor.

Prior to this there was no check on the correctness of the offered digest, except that a 
smart relying party could have looked at the published keys and tried to find a match.  
After this is published as an RFC, the relying part mostly only needs to look at the 
public key data in the file if it exists and not worry about whether it was published.  
This is not "unchanged from RFC 7958" IMO.   Finally, reading this,  why 
wouldn't you explicitly specify that the hash needs to be  (e.g. MUST be) verified 
against either a live (published) key or the included public key?

The check of the Digest element vs. the publickeyinfo is a consistency check 
within the XML, because the data structure does not allow ruling out 
inconsistencies.

Checking the Digest element against a key published elsewhere (e.g. in the root zone) is 
"out of band", and retrieving that key and relying on the outcome of the check 
would actually require trusting the retrieval method. That's why I think this is not a 
plausible way of checking the trust anchor; it's a catch-22 instead.

Best,
Peter

--
https://desec.io/

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