On 19/06/2021 21:07, Marco Möller wrote: > > Hello, > Command apt-key and its man page say that apt-key is deprecated, but > do not suggest an instead recommended tool. It is only mentioned that > keys would now be organized in /etc/apt/trusted.gpg.d/ . But how > should I manage the keys saved there, for instance how to update them, > or what tool of the Debian distribution is managing them there for the > apt functionality of the Debian OS? > Guiding me to a properly up-to-date documentation about this topic > would be welcome! > Marco. For some time, I've been using /etc/apt/trusted.gpg.d rather than using apt-key. As I understand it, keys in apt-key are trusted to sign *any* repository you pull from. That is, if you add a suspicious repository and somehow they were able to push packages signed with their key to the main debian repo servers, then you'd not be able to distinguish between "signed by Debian" and "signed by attacker". Instead, the preferred method is to put binary GPG keys into /etc/apt/trusted.gpg.d (that is, you might need to run "gpg --dearmor" if you download an ascii-armoured key). Files there can have any name it's purely up to the system administrator what the names are, but it makes sense that they indicate the repository they sign. Then, in /etc/apt/sources.list.d/*.list, you need to write: deb [signed-by=/etc/apt/trusted.gpg.d/somekey.gpg] https://repo.attacker.com/ stable main Now, only this repository trusts that key. If packages there are signed by another key, verification fails. Similarly, if packages in another repository are signed by that key, verification fails. You ask about updating them. There is, as far as I know, no automatic method for updating these keys, nor for automatically adding them right now. That's because it's generally considered good practice to add the key manually. You need to actively state that you trust this repository on your system. So, for most repositories, that involves a web page somewhere that says "This is our 'deb ... ' line and this is a link to our public key." The key will usually be valid for several years, but if it does start to fail, apt tools *will* tell you that the key has expired, and that's time to go back and revisit the original site, and see if they have a new key available.
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