[dns-operations] SHA-1 DNSSEC verification broken in RHEL 9 and CentOS 9 Stream

Petr Menšík pemensik at redhat.com
Thu Apr 14 08:57:17 UTC 2022

No, I wanted just the first message to reach both, because I am
subscribed to both lists. Interested people can search archives of the
other list. I expected those lists have very likely disjoint members not
able to write to both.

Feel free to remove epel-devel from further responses here to avoid
receiving errors (and vice versa).

On 4/14/22 00:49, Mark Andrews wrote:
> If you wanted epel-devel list members to see the discussion you have failed.
> Your message to the epel-devel mailing-list was rejected for the following
> reasons:
> The message is not from a list member
> The original message as received by Mailman is attached.
> From: Mark Andrews <marka at isc.org>
> Subject: Re: [dns-operations] SHA-1 DNSSEC verification broken in RHEL 9 and CentOS 9 Stream
> Date: 14 April 2022 at 08:44:55 AEST
> To: Petr Menšík <pemensik at redhat.com>
> Cc: DNS-Operations <dns-operations at dns-oarc.net>, epel-devel at lists.fedoraproject.org
> The only way to detect if the server is running in this mode is to actually attempt a verification and to see if it fails.  That requires precomputed signatures as you can’t sign using RSASHA1 in FIPS mode but you can verify RSASHA1 in FIPS mode.
I am not sure what is the platform you are describing. RHEL 9 won't be
able to verify RSASHA1 signature even in default policy, let alone in
FIPS mode.
> In FIPS mode one can check if the server is running in FIPS mode or not by calling FIPS_mode() or EVP_default_properties_is_fips_enabled() and you can adjust the list of algorithms supported by libcrypto at runtime before attempting to validate anything.  You don’t end up doing a lot of work just to have EVP_VerifyFinal() fail because of an unsignalled policy switch.
> Mark
Yes, I find it also disturbing that there is no good public API to check
SHA-1 availability except attempting a real crypto operation. I hope
that will improve later, but I don't know well working candidate API at
the moment.

Petr Menšík
Software Engineer
Red Hat, http://www.redhat.com/
email: pemensik at redhat.com
PGP: DFCF908DB7C87E8E529925BC4931CA5B6C9FC5CB

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