One of the pieces of hardware I own and opereate is a HP printer. Most of the time it acts as a ... well, paperweight. Then there is an urgent need to have an A4 with information to be delivered somewhere.
As a keen enthusiast for custom TLS certificates, I always take the option to install one. Especially to a LAN-connected device like printer. This one, however, is broken:
All I can manage from it is: "The format of the file is invalid."
Not so cool. Uh!
For troubleshooting, I looked at Error message "The format of the file is invalid" when attempting to import certificate on HP printer and No more ssl certificate update possible. Both are pretty much stating it doesn't work. Couple years ago in Installing TLS certificates on HP printers automatically the thing worked.
In an attempt to solve this, I exported the generated self-signed key as PKCS #12. Certificate has rather "interesting" crypto, pbeWithSHA1And40BitRC2-CBC, Iteration 2048. That is a seriously obsoleted one! Private key has pbeWithSHA1And3-KeyTripleDES-CBC, Iteration 2048, which is also on the tired side. MAC verification has iteration count 1, which is well aligned with the other insecurity.
No matter what I do, AES, DES, 3-DES, RC2, the PKCS #12 won't import. Neither will CA root cert as PEM.
My conclusion has to be the same: recent firmware upgrades have broken the import.
Multiple hours wasted on that! Darn.