user@host:~$ sudo apt update
[sudo] password for user:
Get:1 tor+https://fasttrack.debian.net/debian bullseye-fasttrack InRelease [12.9 kB]
Hit:2 tor+https://deb.whonix.org bullseye InRelease
Hit:3 tor+https://deb.debian.org/debian bullseye InRelease
Get:4 tor+https://deb.debian.org/debian bullseye-updates InRelease [39.4 kB]
Get:6 tor+https://deb.debian.org/debian-security bullseye-security InRelease [44.1 kB]
Get:7 tor+https://deb.debian.org/debian bullseye-backports InRelease [44.2 kB]
Get:8 tor+https://deb.debian.org/debian bullseye-updates/main amd64 Packages.diff/Index [4,995 B]
Get:9 tor+https://deb.debian.org/debian-security bullseye-security/main amd64 Packages [113 kB]
Get:10 tor+https://deb.debian.org/debian bullseye-backports/main amd64 Packages.diff/Index [63.3 kB]
Get:11 tor+https://deb.debian.org/debian bullseye-updates/main amd64 Packages T-2022-01-24-2024.03-F-2022-01-24-2024.03.pdiff [1,102 B]
Get:11 tor+https://deb.debian.org/debian bullseye-updates/main amd64 Packages T-2022-01-24-2024.03-F-2022-01-24-2024.03.pdiff [1,102 B]
Get:12 tor+https://deb.debian.org/debian bullseye-backports/main amd64 Packages T-2022-01-25-0801.56-F-2022-01-25-0208.24.pdiff [3,360 B]
Get:12 tor+https://deb.debian.org/debian bullseye-backports/main amd64 Packages T-2022-01-25-0801.56-F-2022-01-25-0208.24.pdiff [3,360 B]
Get:5 http://ftp.halifax.rwth-aachen.de/kali kali-rolling InRelease [30.6 kB]
Err:5 http://ftp.halifax.rwth-aachen.de/kali kali-rolling InRelease
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY ED444FF07D8D0BF6
Reading package lists... Done
W: GPG error: http://ftp.halifax.rwth-aachen.de/kali kali-rolling InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY ED444FF07D8D0BF6
E: The repository 'http://http.kali.org/kali kali-rolling InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.