On Wed, 21 May 2025, Wes Hardaker wrote:
Paul Wouters via Datatracker <[email protected]> writes:Zone owners currently making use of SHA-1 based algorithms should immediately switch to algorithms I would use "should immediately rollover to algorithms" to avoid the illusion some inexperienced DNS admins might have that they can just "switch" the algorithm without proper prep work of doing a real roll over.I changed to "roll" instead as "rollover" is kinda an odd term (though heavily used by investment firms).
Sounds good.
As a result, SHA-1 is no longer fully interoperable in the context of DNSSEC. As adequate alternatives exist, the use of SHA-1 is no longer advisable. That should be, "SHA-1 as part of a signature algorithm". Because the document isn't obsoleting SHA-1 from DS hashing algorithms right?
Fair point, done.
Thanks.
In the Operational Considerations, one could add a sentence about the difference of not supporting SHA-1 versus having a system that does not support SHA-1. The first results in an insecure validation, which is okay. The second can result in ServFail, which is not okay. Something along the lines of: When not supporting or disabling SHA-1, care should be given by implementers that the DNS software itself is made aware not to consume SHA-1. For example, disabling SHA-1 at the Operating System level could result in SHA-1 cryptographic failures within the DNS system, which would result in those zones failing, instead of the zones being treated as unsigned/insecureI'm not sure that fully works. I'd rather not try to find all the right lines where SHA-1 could be implemented and/or removed. It is certainly possible, for example, for the OS to have removed SHA-1 but the application itself has its own implementation that it brings in. In fact, in Net-SNMP we do just this: we have a portion of openssl with just the algorithms we need in the code base that can be enabled with a flag to specifically avoid linking to a bunch larger library with a bunch of stuff we don't need. How about: Implementations following this advice need to ensure the associated operating system and software libraries they depend upon have SHA-1 support. Though I'm not sure how much that is actually adding. But it does warn about the odd situation of today's environment I suppose.
or: Care should be taken that DNS software supporting algorithms that the operating system or cryptographic libraries have disabled can cause DNS resolution failures, as opposed to DNS software that knowingly disables an algorithm and treats those algoritms as not present, resulting in resolution as if the zone was not signed. Paul _______________________________________________ DNSOP mailing list -- [email protected] To unsubscribe send an email to [email protected]
