How can I remove gpg key that I added using apt-key add -?

Question

I don't need the key in my server's keyring anymore. Is it possible to remove it? I added the key using this command:

 curl http://repo.varnish-cache.org/debian/GPG-key.txt | apt-key add -

Thanks for helping

Answer 1

On 16.10 the short key id is no longer shown when you use the list command, but it is actually the last 8 characters of the long hex.

So for example the key id for the following key

/etc/apt/trusted.gpg.d/ubuntu-keyring-2012-cdimage.gpg
------------------------------------------------------
pub   rsa4096 2012-05-11 [SC]
      8439 38DF 228D 22F7 B374  2BC0 D94A A3F0 EFE2 1092
uid           [ unknown] Ubuntu CD Image Automatic Signing Key (2012) <cdimage@ubuntu.com>

The key id will be EFE21092

Answer 2

First you need to find the key id of the key you added. Do this by the command:

sudo apt-key list

It will list all the keys that you have, with each entry looking like this:

pub   1024R/B455BEF0 2010-07-29
uid                  Launchpad clicompanion-nightlies

Once you have figured out which key to remove, use the command sudo apt-key del <keyid> where <keyid> is replaced with the actual keyid of the key you want to remove from your keyring.

$ sudo apt-key del B455BEF0
$ apt-key list | grep clicompan
$

Answer 3

Update for Ubuntu 20.04

after running

sudo apt-key list

you should get the list of apt keys:

/etc/apt/trusted.gpg
--------------------
pub   rsa4096 2016-04-12 [SC]
      EB4C 1BFD 4F04 2F6D DDCC  EC91 7721 F63B D38B 4796
uid           [ unknown] Google Inc. (Linux Packages Signing Authority) <linux-packages-keymaster@google.com>
sub   rsa4096 2019-07-22 [S] [expires: 2022-07-21]

pub   rsa4096 2017-04-11 [SC] [expired: 2019-09-28]
      D4CC 8597 4C31 396B 18B3  6837 D615 560B A5C7 FF72
uid           [ expired] Opera Software Archive Automatic Signing Key 2017 <packager@opera.com>

pub   rsa4096 2019-09-12 [SC] [expires: 2021-09-11]
      68E9 B2B0 3661 EE3C 44F7  0750 4B8E C3BA ABDC 4346
uid           [ unknown] Opera Software Archive Automatic Signing Key 2019 <packager@opera.com>
sub   rsa4096 2019-09-12 [E] [expires: 2021-09-11]

pub   rsa4096 2017-03-13 [SC]
      8CAE 012E BFAC 38B1 7A93  7CD8 C5E2 2450 0C12 89C0
uid           [ unknown] TeamViewer GmbH (TeamViewer Linux 2017) <support@teamviewer.com>
sub   rsa4096 2017-03-13 [E]

under uid you have the name of the app, for example:

[ unknown] Opera Software Archive Automatic Signing Key 2019 <packager@opera.com>

and the key you want to delete is above it:

    D4CC 8597 4C31 396B 18B3  6837 D615 560B A5C7 FF72  <-- THAT'S THE KEY
uid           [ expired] Opera Software Archive Automatic Signing Key 2017 <packager@opera.com>

and you remove it by putting that key inside double or single quotes like this:

sudo apt-key del "D4CC 8597 4C31 396B 18B3  6837 D615 560B A5C7 FF72"

Answer 4

I made a short script to make things easier and using a string instead of the id.

You can use my script if the key contains a unique string you know.
e.g. in my case for webmin

pub   1024D/11F63C51 2002-02-28
uid                  Jamie Cameron <jcameron@webmin.com>
sub   1024g/1B24BE83 2002-02-28

I'm sure only the webmin key on my system has jcameron than I use this script to remove the according key.

I saved it as ~/removeAptKey

and run it as

sudo ./removeAptKey jcameron

The ouput should be something like

KEYID: 11F63C51
OK

Here is my script:

#!/bin/bash

function printKeys(){
    echo "Installed keys are"
    echo ""
    sudo apt-key list
}

if [[ $EUID -ne 0 ]]; then
   echo "This script must be run as root" 1>&2
   exit 1
fi

if [[ $# -eq 0 ]]
then
    echo "No key name provided"
    exit 1
fi

UNIQUE=$1

sudo apt-key list | grep "${UNIQUE}" -B 1 > result.temp

LENGTH=$(cat result.temp | wc -l)

if [[ ${LENGTH} -gt 2 ]]
then
    echo "Attention you found more than 1 key. Use a more specific string."
    printKeys
    exit 2
fi

if [[ ${LENGTH} != 2 ]]
then
    echo "Key not found. Doing nothing."
    printKeys
    exit 3
fi

KEYID=$(cat result.temp | grep 'pub' | cut -d " " -f 4 | cut -d "/" -f 2)
echo "KEYID: "$KEYID

apt-key del ${KEYID}

rm result.temp

First I get the upper two lines of my key's block:

• sudo apt-key list: lists the apt keys as usual
• grep '${UNIQUE}' -B 1: take only the line containing the unique key string jcameron and -B 1 the line before
• > result.temp: Save it in a file (which is later removed)

If this returns exactly 2 lines (-> got exactly 1 key) I move on:

• grep 'pub': Now take only the line with the pup key id
• cut -d " " -f 4: take the 4th word of that line (the first is pub than come two spaces, than the string we are after ``)
• cut -d "/" -f 2: take only the part after /

And finally delete this key and cleanup

• apt-key del ${KEYID} (in my case 11F63C51)
• rm result.temp: don't need this file anymore

Answer 5

I know I might be late, but just wanted to share this one-line command to achieve this.

NOTE: This will only work if the output is an unique key.

---

Ubuntu versions up to 16.04 (UPDATED 2018-12-22):

apt-key del $(apt-key list | awk 'NR=='$(apt-key list | grep --line-number --regexp "FOOBAR" | cut --fields 1 --delimiter ":")'{print;exit}' | awk '{print $2}' | cut --fields 2 --delimiter "/")

where FOOBAR is the UID name.

---

Ubuntu versions from 16.10:

apt-key del $(apt-key list | awk 'NR=='`expr $(apt-key list | grep --line-number --regexp "FOOBAR" | cut --fields 1 --delimiter ":") - 1`'{print;exit}')

where FOOBAR is the UID name.

Answer 6

I did this,

sudo apt-key list

Find the 'expired' key, then delete it, in my case,

sudo apt-key del "31CF B0B6 5659 B5D4 0DEE  C98D DFA1 75A7 5104 960E"

Then do

sudo apt update

The deleted key will say its not available note that string, in my case DFA175A75104960E

Then update the key like this, for my case DFA175A75104960E needed update,

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys DFA175A75104960E

Should work now.

Answer 7

If you happen to have the .asc key file, you can be sure you are deleting the right key with a command like this. (Replace mykey.asc with your key file below.)

apt-key del "$(gpg -n -q --import --import-options import-show mykey.asc | grep '^pub' -A 1 | tail -n 1 | xargs)"

This command seems to work on Ubuntu 20.04. Credit for the gpg command goes to maxschlepzig for their answer here.

Answer 8

Maybe I'm missing something... but you can use the GUI also, on Settings of Software Updater: