Background: as specified in draft-ietf-dnsop-rfc8624-bis, the goal of
algorithm update documents like the draft-ietf-dnsop-must-not-sha1 document
should clearly differentiate between whether a requirement is targeting
implementations or the deployments (operators). Both of these documents are
currently in the RFC Editors queue, and as such the authors believe they
should be changed as minimally as possible in order to fix any current
misunderstandings. The point behind the draft-ietf-dnsop-must-not-sha1
document was to recommend that all deployment of SHA1 algorithms in DNSSEC
stop.. But, because there is an existing sizable deployment level, that
implementations should continue to provide implementation of the algorithms
even if their defaults were to use a different set of algorithms. Basically,
if an operator feels that they really need to still support SHA-1, the
software that they use needs to still have it available within the
implementation.

One late change in the document produced two issues that were only very
recently caught (thanks Mukund for finding these):

1. As pointed out, draft-ietf-dnsop-must-not-sha1 states “Validating
resolvers MUST treat RSASHA1 and RSASHA1-NSEC3-SHA1 DS records as insecure”.
This sentence is confusing in that it’s unclear if it is speaking to
implementers or operators. To fix the intent of this, we suggest changing
this to “Validating resolvers MUST be configured to treat RSASHA1 and
RSASHA1-NSEC3-SHA1 DS records as insecure”, directing the requirement toward
those deploying DNSSEC, not those implementing it within validating
resolvers.

2. The document also states “Because of RSASHA1 and RSASHA1-NSEC3-SHA1's
non-zero use, deployed validating resolvers MAY be configured to continue to
validate RRSIG records that use these algorithms.”, which clearly conflicts
with the MUST NOT above. There are two options to fix this in a minimal way:

2a. Remove this requirement entirely, as it goes against the principle of the
document to stop using SHA1 (and thus treat it as insecure).

2b.Change the MUST in the first sentence to SHOULD NOT so the MAY is no
longer in conflict.


The authors will look to the chairs and ADs to determine whether
consensus was reached on these specific two decisions and suggest 2
weeks as a reasonable time frame for a conclusion on this.


[no hats]: Speaking personally, I think option 2a is better and signals
what we really want. Operators can already ignore MUSTs without being
told they can do so.

-- 
Wes Hardaker
USC/ISI

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