Comment 21 for bug 1433761

{juliank, magnetik},

I checked add-apt-repository operation about a week ago while testing some (unrelated) automation changes on bionic with proxy environment variables and it was fine.

apt-key should not be used at all due to its deprecated functionality.

For your reference:

The manpage for apt-key mentions the following in a section about the
"add" command:
"Note: Instead of using this command a keyring should be placed directly in the /etc/apt/trusted.gpg.d/ directory with a descriptive name and either "gpg" or "asc" as file extension."

The support for /etc/apt/trusted.gpg.d/ goes back to 2010:
https://salsa.debian.org/nathanruiz-guest/apt/commit/c24f6ce22cd6720004addad2e3382b3caa6b1b7c

Debian is dropping apt-key usage as well based on what I see:
https://salsa.debian.org/live-team/live-build/merge_requests/11

Using "asc" in this directory is only supported as of apt 1.4 (on versions before that gpg --dearmor can be used to transform a key to the binary form).

https://salsa.debian.org/nathanruiz-guest/apt/commit/f77ea8235cafb258d1cb0b2b90e95aa36e5c4650
https://salsa.debian.org/nathanruiz-guest/apt/commit/2906182db398419a9c59a928b7ae73cf7c7aa307