unresolved@debian:~$ sudo apt-get update
[sudo] password for unresolved:
Ign:1 http://ftp.debian.org/debian stretch-backprts InRelease
Ign:2 http://ppa.launchpad.net/diesch/testing/ubuntu artful InRelease
Hit:4 http://ftp.debian.org/debian stretch-backports InRelease
Ign:5 http://deb.debian.org/debian stable InRelease
Err:6 http://ppa.launchpad.net/diesch/testing/ubuntu artful Release
  404  Not Found
Err:7 http://ftp.debian.org/debian stretch-backprts Release
  404  Not Found [IP: 130.89.148.12 80]
Hit:8 http://deb.debian.org/debian stable-updates InRelease
Get:3 http://archive-4.kali.org/kali kali-rolling InRelease [30.5 kB]
Hit:9 http://deb.debian.org/debian-security stable/updates InRelease
Hit:10 http://deb.debian.org/debian stable Release
Err:3 http://archive-4.kali.org/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: http://ftp.debian.org/debian/dists/stretch-backports/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg are ignored as the file is not readable by user '_apt' executing apt-key.
E: The repository 'http://ppa.launchpad.net/diesch/testing/ubuntu artful Release' does not have a Release file.
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.
E: The repository 'http://ftp.debian.org/debian stretch-backprts Release' does not have a Release file.
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.
W: http://deb.debian.org/debian/dists/stable-updates/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg are ignored as the file is not readable by user '_apt' executing apt-key.
W: http://deb.debian.org/debian-security/dists/stable/updates/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg are ignored as the file is not readable by user '_apt' executing apt-key.
W: http://deb.debian.org/debian/dists/stable/Release.gpg: The key(s) in the keyring /etc/apt/trusted.gpg are ignored as the file is not readable by user '_apt' executing apt-key.
W: http://http.kali.org/kali/dists/kali-rolling/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg are ignored as the file is not readable by user '_apt' executing apt-key.
W: GPG error: http://archive-4.kali.org/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.