How to suppress "WARNING: This key is not certified with a trusted signature!"

Question

I've been through two Stack Exchange questions/answers and two GPG mailing list posts. I can't seem to clear "WARNING: This key is not certified with a trusted signature!". I would now like to disable it since I can't seem to clear it.

GnuPG shows the problem at Integrity Check, but they don't say how to fix it. They do say:

then you have a copy of our keys and the signatures are valid, but either you have not marked the keys as trusted or the keys are a forgery.

Looking through my gpg.conf I don't see a way to suppress useless warnings like shown below.

How do I suppress the message for a key?

---

The message is below. I've already marked 9306CC77 and subkey 971EDE93 trusted. I logged out and back on. I also rebooted the server. I am ready to move onto another problem.

# ~/do-update.sh
=> Fetching new catalog and descriptions (http://mirror.opencsw.org/opencsw/testing/i386/5.11) if available ...
Checking integrity of /var/opt/csw/pkgutil/catalog.mirror.opencsw.org_opencsw_testing_i386_5.11 with gpg.
gpg: Signature made Sat Apr 20 06:10:03 2019 EDT using DSA key ID 9306CC77
gpg: Good signature from "OpenCSW catalog signing <board@opencsw.org>"
gpg: WARNING: This key is not certified with a trusted signature!
gpg:          There is no indication that the signature belongs to the owner.
Primary key fingerprint: 4DCE 3C80 AAB2 CAB1 E60C  9A3C 05F4 2D66 9306 CC77
==> 4013 packages loaded from /var/opt/csw/pkgutil/catalog.mirror.opencsw.org_opencsw_testing_i386_5.11

Answer 1

Any page that tells you to use --edit-key <id> trust in order to suppress this warning is, generally, going in the completely wrong direction. The confusing message actually has nothing to do with the key's trust setting. A trusted signature is one that was made by a valid key:

• Key validity defines whether this key belongs to the person that it claims.

• Key trust defines whether this key is allowed to sign other keys (Web-of-Trust). In other words, a trusted key may act as a CA and mark other keys as valid, transitively.

So in order to suppress the "untrusted signature" warning on a per-key basis, you have to mark the key as a valid (as that's literally the purpose of this warning).

To mark a key as valid, you usually sign it:

gpg --lsign-key "4DCE 3C80 AAB2 CAB1 E60C  9A3C 05F4 2D66 9306 CC77"

Alternatively if you have the 'tofu' or 'tofu+pgp' trust-model active, you can also do:

gpg --tofu-policy good "4DCE 3C80 AAB2 CAB1 E60C  9A3C 05F4 2D66 9306 CC77"

Now you should see this in --list-keys or --edit-key:

pub  dsa1024/05F42D669306CC77
     created: 2011-08-31  expires: never       usage: SC  
     trust: unknown       validity: full

There is also a config option to suppress this warning for all keys; it's called trust-model always. It means GnuPG acts as if all keys were signed by a fully trusted key.

Finally, subkeys have neither trust nor validity settings, they're only containers for cryptographic parameters so they inherit this from the primary key.