I cannot update my Kali Linux, when trying to execute apt-get update I get this error message.

# apt-get update

Get:1 http://kali.mirror.garr.it/mirrors/kali kali-rolling InRelease [30.5 kB]
Err:1 http://kali.mirror.garr.it/mirrors/kali kali-rolling InRelease
  The following signatures were invalid: EXPKEYSIG ED444FF07D8D0BF6 Kali Linux Repository <devel@kali.org>
Reading package lists... Done
W: GPG error: http://kali.mirror.garr.it/mirrors/kali kali-rolling InRelease: The following signatures were invalid: EXPKEYSIG ED444FF07D8D0BF6 Kali Linux Repository <devel@kali.org>
E: The repository 'http://kali.mirror.garr.it/mirrors/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.

If you need my kernel version.

# uname -a
4.13.0-kali1-amd64 #1 SMP Debian 4.13.10-1kali2 (2017-11-08) x86_64 GNU/Linux

What should i do?

Best Answer

Add the gpg key.

gpg --keyserver hkp://keys.gnupg.net --recv-key 7D8D0BF6

Then check your fingerprint

gpg --fingerprint 7D8D0BF6

Sample output.

pub   rsa4096 2012-03-05 [SC] [expires: 2021-02-03]
      44C6 513A 8E4F B3D3 0875  F758 ED44 4FF0 7D8D 0BF6
uid           [ unknown] Kali Linux Repository <devel@kali.org>
sub   rsa4096 2012-03-05 [E] [expires: 2021-02-03]

then .

gpg -a --export 7D8D0BF6 | apt-key add -
apt update

Debian : SecureApt

update : 8 Feb , 2018.

Answer from the official documentation .

Note that if you haven’t updated your Kali installation in some time (tsk2), you will like receive a GPG error about the repository key being expired (ED444FF07D8D0BF6). Fortunately, this issue is quickly resolved by running the following as root:

wget -q -O - https://archive.kali.org/archive-key.asc | apt-key add