The key(s) in the keyring /etc/apt/trusted.gpg are ignored as the file has an unsupported filetype

Question

I am running Debian 10. I have been getting following error while updating repositories for long time:

$ sudo apt update
Hit:1 http://security.debian.org buster/updates InRelease                        
Hit:2 http://deb.debian.org/debian buster InRelease                              
Hit:3 http://deb.debian.org/debian buster-updates InRelease
Reading package lists... Done
Building dependency tree       
Reading state information... Done
All packages are up to date.
W: http://security.debian.org/dists/buster/updates/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg are ignored as the file has an unsupported filetype.
W: http://deb.debian.org/debian/dists/buster/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg are ignored as the file has an unsupported filetype.
W: http://deb.debian.org/debian/dists/buster-updates/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg are ignored as the file has an unsupported filetype.

How do I get read of this warning regarding keys?

Here is the content of /etc/apt/sources.list

Ask in comment if more information is required.

Solution

You have reported also this command output:

$ sudo apt-key --keyring /etc/apt/trusted.gpg list
/etc/apt/trusted.gpg
--------------------
pub rsa2048 2016-07-13 [SC]
6781 84F1 20A8 7A47 5F65 6972 6C0D AC72 8B29 D817
uid [ unknown] OpenFOAM Foundation <[email protected]>
sub rsa2048 2016-07-13 [E]
pub rsa4096 2017-02-22 [SCEA]
9DC8 5822 9FC7 DD38 854A E2D8 8D81 803C 0EBF CD88
uid [ unknown] Docker Release (CE deb) <[email protected]>
sub rsa4096 2017-02-22 [S]

And that the file had an incorrect type:

# file /etc/apt/trusted.gpg
/etc/apt/trusted.gpg: GPG keybox database version 1, created-at Thu Apr 4 13:19:16 2019, last-maintained Thu Apr 4 13:19:16 2019

Instead of a key public ring (v4) as it should.

The conclusion is that the file has got damaged for some reason.
Most probably because some command failed when you were manually installing either Docker or OpenFOAM (the keys reported above).

---

The solution is simple:

• erase the file (well, move it somewhere else for backup)
• re-add the trusted keys

The docker key you reported: 9DC8 5822 9FC7 DD38 854A E2D8 8D81 803C 0EBF CD88

Could be re-added to the trusted keys data base with:

curl -fsSL https://download.docker.com/linux/debian/gpg | sudo apt-key add -

As explained in this web page

Please be sure to re-check the key signature.

But the other key fingerprint: 6781 84F1 20A8 7A47 5F65 6972 6C0D AC72 8B29 D817

Doesn't appear anywhere on the internet, I would not trust such key.
Don't try to reinstall it.

If needed find a correct guide to install OpenFOAM in Debian.

Good luck.

Note: Blindly installing keys, any key, is a very bad idea, this is the way in which what gets installed in our systems gets verified. If the key to verify comes from an un-trusted source, all installed packages (and the system in general) could no longer be trusted. You have been warned !!.

Added:

OpenFOAM has a package in Debian, there is no need to manually install any external key. That raises the level of warning.

Do you remember installing that key? If not, please reinstall your Debian.

Comments

[Pandya]

Does /etc/apt/trusted.gpg come with Debian installation or created lateron on if we manually adds keys?

[done]

The file /etc/apt/trusted.gpg was used by Debian, but now, most keys get installed in the /etc/apt/trusted.gpg.d/ directory. Go to synaptic, find the package debian-archive-keyring and view its properties (what files it has installed). You will find that all keys for the Debian have been installed in the directory /etc/apt/trusted.gpg.d/. Of course, any manually added key has to be stored somewhere, usually in /etc/apt/trusted.gpg.