Skype - getting rid off cross-signing keys

Adam Przedniczek

4/26/24, 11:39 AM

With a fresh Ubuntu 23.04 installation, I would like to manage all keys in a proper way and get rid off the cross-siging threat.

I've installed Skype simply by:

wget -c https://repo.skype.com/latest/skypeforlinux-64.deb
dpkg -i skypeforlinux-64.deb

Unfortunatelly, I've discovered (in apt-key list) that Skype key was stored in a common file /etc/apt/trusted.gpg.

So, I've downloaded Skype key once again, but to a separate file, but not in /usr/share/keyrings/

curl -sS https://repo.skype.com/data/SKYPE-GPG-KEY | gpg --dearmor | tee /etc/apt/trusted.gpg.d/skype.gpg

And my Question #1 is: Do I have to update the file /etc/apt/sources.list.d/skype-stable.list to something like:

deb [arch=amd64 signed-by=/etc/apt/trusted.gpg.d/skype.gpg] https://repo.skype.com/deb stable main

I'm asking this, because Chrome installation created a separate key file /etc/apt/trusted.gpg.d/google-chrome.gpg, however in corresponding source list file /etc/apt/sources.list.d/google-chrome.list, there's no singed-by option:

deb [arch=amd64] https://dl.google.com/linux/chrome/deb/ stable main

It seems Chrome is working fine without this option and I'm a little bit confused.

Question #2: What is the most suitable location for the separate key files?

/etc/apt/trusted.gpg.d/
/usr/share/keyrings/
/etc/apt/keyrings/

What are the nuances between these three locations?

0 + 0

package-management

apt

keyrings

gnupg

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Skype - getting rid off cross-signing keys

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